Commit graph

410 commits

Author SHA1 Message Date
Peter Dillinger 2d0380adbe Allow manifest fix-up without requiring prior state (#10796)
Summary:
This change is motivated by ensuring that `ldb update_manifest` or `UpdateManifestForFilesState` can run without expecting files to open when the old temperature is provided (in case the FileSystem strictly interprets non-kUnknown), but ended up fixing a problem in `OfflineManifestWriter` (used by `ldb unsafe_remove_sst_file`) where it would open some SST files during recovery and expect them to match the prior manifest state, even if not required by the intended new state.

Also update BackupEngine to retry with Temperature kUnknown when reading file with potentially "wrong" temperature.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10796

Test Plan: tests added/updated, that fail before the change(s) and now pass

Reviewed By: jay-zhuang

Differential Revision: D40232645

Pulled By: jay-zhuang

fbshipit-source-id: b5aa2688aecfe0c320b80a7da689b315414c20be
2022-10-10 17:59:17 -07:00
anand76 37b75e1364 Fix some MultiGet stats (#10673)
Summary:
The stats were not accurate for the coroutine version of MultiGet. This PR fixes it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10673

Reviewed By: akankshamahajan15

Differential Revision: D39492615

Pulled By: anand1976

fbshipit-source-id: b46c04e15ea27e66f4c31f00c66497aa283bf9d3
2022-09-15 22:48:06 -07:00
Peter Dillinger 6de7081cf3 Always verify SST unique IDs on SST file open (#10532)
Summary:
Although we've been tracking SST unique IDs in the DB manifest
unconditionally, checking has been opt-in and with an extra pass at DB::Open
time. This changes the behavior of `verify_sst_unique_id_in_manifest` to
check unique ID against manifest every time an SST file is opened through
table cache (normal DB operations), replacing the explicit pass over files
at DB::Open time. This change also enables the option by default and
removes the "EXPERIMENTAL" designation.

One possible criticism is that the option no longer ensures the integrity
of a DB at Open time. This is far from an all-or-nothing issue. Verifying
the IDs of all SST files hardly ensures all the data in the DB is readable.
(VerifyChecksum is supposed to do that.) Also, with
max_open_files=-1 (default, extremely common), all SST files are
opened at DB::Open time anyway.

Implementation details:
* `VerifySstUniqueIdInManifest()` functions are the extra/explicit pass
that is now removed.
* Unit tests that manipulate/corrupt table properties have to opt out of
this check, because that corrupts the "actual" unique id. (And even for
testing we don't currently have a mechanism to set "no unique id"
in the in-memory file metadata for new files.)
* A lot of other unit test churn relates to (a) default checking on, and
(b) checking on SST open even without DB::Open (e.g. on flush)
* Use `FileMetaData` for more `TableCache` operations (in place of
`FileDescriptor`) so that we have access to the unique_id whenever
we might need to open an SST file. **There is the possibility of
performance impact because we can no longer use the more
localized `fd` part of an `FdWithKeyRange` but instead follow the
`file_metadata` pointer. However, this change (possible regression)
is only done for `GetMemoryUsageByTableReaders`.**
* Removed a completely unnecessary constructor overload of
`TableReaderOptions`

Possible follow-up:
* Verification only happens when opening through table cache. Are there
more places where this should happen?
* Improve error message when there is a file size mismatch vs. manifest
(FIXME added in the appropriate place).
* I'm not sure there's a justification for `FileDescriptor` to be distinct from
`FileMetaData`.
* I'm skeptical that `FdWithKeyRange` really still makes sense for
optimizing some data locality by duplicating some data in memory, but I
could be wrong.
* An unnecessary overload of NewTableReader was recently added, in
the public API nonetheless (though unusable there). It should be cleaned
up to put most things under `TableReaderOptions`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10532

Test Plan:
updated unit tests

Performance test showing no significant difference (just noise I think):
`./db_bench -benchmarks=readwhilewriting[-X10] -num=3000000 -disable_wal=1 -bloom_bits=8 -write_buffer_size=1000000 -target_file_size_base=1000000`
Before: readwhilewriting [AVG 10 runs] : 68702 (± 6932) ops/sec
After: readwhilewriting [AVG 10 runs] : 68239 (± 7198) ops/sec

Reviewed By: jay-zhuang

Differential Revision: D38765551

Pulled By: pdillinger

fbshipit-source-id: a827a708155f12344ab2a5c16e7701c7636da4c2
2022-09-07 22:52:42 -07:00
Changyu Bi 30bc495c03 Skip swaths of range tombstone covered keys in merging iterator (2022 edition) (#10449)
Summary:
Delete range logic is moved from `DBIter` to `MergingIterator`, and `MergingIterator` will seek to the end of a range deletion if possible instead of scanning through each key and check with `RangeDelAggregator`.

With the invariant that a key in level L (consider memtable as the first level, each immutable and L0 as a separate level) has a larger sequence number than all keys in any level >L, a range tombstone `[start, end)` from level L covers all keys in its range in any level >L. This property motivates optimizations in iterator:
- in `Seek(target)`, if level L has a range tombstone `[start, end)` that covers `target.UserKey`, then for all levels > L, we can do Seek() on `end` instead of `target` to skip some range tombstone covered keys.
- in `Next()/Prev()`, if the current key is covered by a range tombstone `[start, end)` from level L, we can do `Seek` to `end` for all levels > L.

This PR implements the above optimizations in `MergingIterator`. As all range tombstone covered keys are now skipped in `MergingIterator`, the range tombstone logic is removed from `DBIter`. The idea in this PR is similar to https://github.com/facebook/rocksdb/issues/7317, but this PR leaves `InternalIterator` interface mostly unchanged. **Credit**: the cascading seek optimization and the sentinel key (discussed below) are inspired by [Pebble](https://github.com/cockroachdb/pebble/blob/master/merging_iter.go) and suggested by ajkr in https://github.com/facebook/rocksdb/issues/7317. The two optimizations are mostly implemented in `SeekImpl()/SeekForPrevImpl()` and `IsNextDeleted()/IsPrevDeleted()` in `merging_iterator.cc`. See comments for each method for more detail.

One notable change is that the minHeap/maxHeap used by `MergingIterator` now contains range tombstone end keys besides point key iterators. This helps to reduce the number of key comparisons. For example, for a range tombstone `[start, end)`, a `start` and an `end` `HeapItem` are inserted into the heap. When a `HeapItem` for range tombstone start key is popped from the minHeap, we know this range tombstone becomes "active" in the sense that, before the range tombstone's end key is popped from the minHeap, all the keys popped from this heap is covered by the range tombstone's internal key range `[start, end)`.

Another major change, *delete range sentinel key*, is made to `LevelIterator`. Before this PR, when all point keys in an SST file are iterated through in `MergingIterator`, a level iterator would advance to the next SST file in its level. In the case when an SST file has a range tombstone that covers keys beyond the SST file's last point key, advancing to the next SST file would lose this range tombstone. Consequently, `MergingIterator` could return keys that should have been deleted by some range tombstone. We prevent this by pretending that file boundaries in each SST file are sentinel keys. A `LevelIterator` now only advance the file iterator once the sentinel key is processed.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10449

Test Plan:
- Added many unit tests in db_range_del_test
- Stress test: `./db_stress --readpercent=5 --prefixpercent=19 --writepercent=20 -delpercent=10 --iterpercent=44 --delrangepercent=2`
- Additional iterator stress test is added to verify against iterators against expected state: https://github.com/facebook/rocksdb/issues/10538. This is based on ajkr's previous attempt https://github.com/facebook/rocksdb/pull/5506#issuecomment-506021913.

```
python3 ./tools/db_crashtest.py blackbox --simple --write_buffer_size=524288 --target_file_size_base=524288 --max_bytes_for_level_base=2097152 --compression_type=none --max_background_compactions=8 --value_size_mult=33 --max_key=5000000 --interval=10 --duration=7200 --delrangepercent=3 --delpercent=9 --iterpercent=25 --writepercent=60 --readpercent=3 --prefixpercent=0 --num_iterations=1000 --range_deletion_width=100 --verify_iterator_with_expected_state_one_in=1
```

- Performance benchmark: I used a similar setup as in the blog [post](http://rocksdb.org/blog/2018/11/21/delete-range.html) that introduced DeleteRange, "a database with 5 million data keys, and 10000 range tombstones (ignoring those dropped during compaction) that were written in regular intervals after 4.5 million data keys were written".  As expected, the performance with this PR depends on the range tombstone width.
```
# Setup:
TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=fillrandom --writes=4500000 --num=5000000
TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=overwrite --writes=500000 --num=5000000 --use_existing_db=true --writes_per_range_tombstone=50

# Scan entire DB
TEST_TMPDIR=/dev/shm ./db_bench_main --benchmarks=readseq[-X5] --use_existing_db=true --num=5000000 --disable_auto_compactions=true

# Short range scan (10 Next())
TEST_TMPDIR=/dev/shm/width-100/ ./db_bench_main --benchmarks=seekrandom[-X5] --use_existing_db=true --num=500000 --reads=100000 --seek_nexts=10 --disable_auto_compactions=true

# Long range scan(1000 Next())
TEST_TMPDIR=/dev/shm/width-100/ ./db_bench_main --benchmarks=seekrandom[-X5] --use_existing_db=true --num=500000 --reads=2500 --seek_nexts=1000 --disable_auto_compactions=true
```
Avg over of 10 runs (some slower tests had fews runs):

For the first column (tombstone), 0 means no range tombstone, 100-10000 means width of the 10k range tombstones, and 1 means there is a single range tombstone in the entire DB (width is 1000). The 1 tombstone case is to test regression when there's very few range tombstones in the DB, as no range tombstone is likely to take a different code path than with range tombstones.

- Scan entire DB

| tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% |
| ------------- | ------------- | ------------- |  ------------- |
| 0 range tombstone    |2525600 (± 43564)    |2486917 (± 33698)    |-1.53%               |
| 100   |1853835 (± 24736)    |2073884 (± 32176)    |+11.87%              |
| 1000  |422415 (± 7466)      |1115801 (± 22781)    |+164.15%             |
| 10000 |22384 (± 227)        |227919 (± 6647)      |+918.22%             |
| 1 range tombstone      |2176540 (± 39050)    |2434954 (± 24563)    |+11.87%              |
- Short range scan

| tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% |
| ------------- | ------------- | ------------- |  ------------- |
| 0  range tombstone   |35398 (± 533)        |35338 (± 569)        |-0.17%               |
| 100   |28276 (± 664)        |31684 (± 331)        |+12.05%              |
| 1000  |7637 (± 77)          |25422 (± 277)        |+232.88%             |
| 10000 |1367                 |28667                |+1997.07%            |
| 1 range tombstone      |32618 (± 581)        |32748 (± 506)        |+0.4%                |

- Long range scan

| tombstone width | Pre-PR ops/sec | Post-PR ops/sec | ±% |
| ------------- | ------------- | ------------- |  ------------- |
| 0 range tombstone     |2262 (± 33)          |2353 (± 20)          |+4.02%               |
| 100   |1696 (± 26)          |1926 (± 18)          |+13.56%              |
| 1000  |410 (± 6)            |1255 (± 29)          |+206.1%              |
| 10000 |25                   |414                  |+1556.0%             |
| 1 range tombstone   |1957 (± 30)          |2185 (± 44)          |+11.65%              |

- Microbench does not show significant regression: https://gist.github.com/cbi42/59f280f85a59b678e7e5d8561e693b61

Reviewed By: ajkr

Differential Revision: D38450331

Pulled By: cbi42

fbshipit-source-id: b5ef12e8d8c289ed2e163ccdf277f5039b511fca
2022-09-02 09:51:19 -07:00
Hui Xiao e484b81eee Sync dir containing CURRENT after RenameFile on CURRENT as much as possible (#10573)
Summary:
**Context:**
Below crash test revealed a bug that directory containing CURRENT file (short for `dir_contains_current_file` below) was not always get synced after a new CURRENT is created and being called with `RenameFile` as part of the creation.

This bug exposes a risk that such un-synced directory containing the updated CURRENT can’t survive a host crash (e.g, power loss) hence get corrupted. This then will be followed by a recovery from a corrupted CURRENT that we don't want.

The root-cause is that a nullptr `FSDirectory* dir_contains_current_file` sometimes gets passed-down to `SetCurrentFile()` hence in those case `dir_contains_current_file->FSDirectory::FsyncWithDirOptions()` will be skipped  (which otherwise will internally call`Env/FS::SyncDic()` )
```
./db_stress --acquire_snapshot_one_in=10000 --adaptive_readahead=1 --allow_data_in_errors=True --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=100000 --batch_protection_bytes_per_key=8 --block_size=16384 --bloom_bits=134.8015470676662 --bottommost_compression_type=disable --cache_size=8388608 --checkpoint_one_in=1000000 --checksum_type=kCRC32c --clear_column_family_one_in=0 --compact_files_one_in=1000000 --compact_range_one_in=1000000 --compaction_pri=2 --compaction_ttl=100 --compression_max_dict_buffer_bytes=511 --compression_max_dict_bytes=16384 --compression_type=zstd --compression_use_zstd_dict_trainer=1 --compression_zstd_max_train_bytes=65536 --continuous_verification_interval=0 --data_block_index_type=0 --db=$db --db_write_buffer_size=1048576 --delpercent=5 --delrangepercent=0 --destroy_db_initially=0 --disable_wal=0 --enable_compaction_filter=0 --enable_pipelined_write=1 --expected_values_dir=$exp --fail_if_options_file_error=1 --file_checksum_impl=none --flush_one_in=1000000 --get_current_wal_file_one_in=0 --get_live_files_one_in=1000000 --get_property_one_in=1000000 --get_sorted_wal_files_one_in=0 --index_block_restart_interval=4 --ingest_external_file_one_in=0 --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True --mark_for_compaction_one_file_in=10 --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=10000 --max_key_len=3 --max_manifest_file_size=16384 --max_write_batch_group_size_bytes=64 --max_write_buffer_number=3 --max_write_buffer_size_to_maintain=0 --memtable_prefix_bloom_size_ratio=0.001 --memtable_protection_bytes_per_key=1 --memtable_whole_key_filtering=1 --mmap_read=1 --nooverwritepercent=1 --open_metadata_write_fault_one_in=0 --open_read_fault_one_in=0 --open_write_fault_one_in=0 --ops_per_thread=100000000 --optimize_filters_for_memory=1 --paranoid_file_checks=1 --partition_pinning=2 --pause_background_one_in=1000000 --periodic_compaction_seconds=0 --prefix_size=5 --prefixpercent=5 --prepopulate_block_cache=1 --progress_reports=0 --read_fault_one_in=1000 --readpercent=45 --recycle_log_file_num=0 --reopen=0 --ribbon_starting_level=999 --secondary_cache_fault_one_in=32 --secondary_cache_uri=compressed_secondary_cache://capacity=8388608 --set_options_one_in=10000 --snapshot_hold_ops=100000 --sst_file_manager_bytes_per_sec=0 --sst_file_manager_bytes_per_truncate=0 --subcompactions=3 --sync_fault_injection=1 --target_file_size_base=2097 --target_file_size_multiplier=2 --test_batches_snapshots=1 --top_level_index_pinning=1 --use_full_merge_v1=1 --use_merge=1 --value_size_mult=32 --verify_checksum=1 --verify_checksum_one_in=1000000 --verify_db_one_in=100000 --verify_sst_unique_id_in_manifest=1 --wal_bytes_per_sync=524288 --write_buffer_size=4194 --writepercent=35
```

```
stderr:
WARNING: prefix_size is non-zero but memtablerep != prefix_hash
db_stress: utilities/fault_injection_fs.cc:748: virtual rocksdb::IOStatus rocksdb::FaultInjectionTestFS::RenameFile(const std::string &, const std::string &, const rocksdb::IOOptions &, rocksdb::IODebugContext *): Assertion `tlist.find(tdn.second) == tlist.end()' failed.`
```

**Summary:**
The PR ensured the non-test path pass down a non-null dir containing CURRENT (which is by current RocksDB assumption just db_dir) by doing the following:
- Renamed `directory_to_fsync` as `dir_contains_current_file` in `SetCurrentFile()` to tighten the association between this directory and CURRENT file
- Changed `SetCurrentFile()` API to require `dir_contains_current_file` being passed-in, instead of making it by default nullptr.
    -  Because `SetCurrentFile()`'s `dir_contains_current_file` is passed down from `VersionSet::LogAndApply()` then `VersionSet::ProcessManifestWrites()` (i.e, think about this as a chain of 3 functions related to MANIFEST update), these 2 functions also got refactored to require `dir_contains_current_file`
- Updated the non-test-path callers of these 3 functions to obtain and pass in non-nullptr `dir_contains_current_file`, which by current assumption of RocksDB, is the `FSDirectory* db_dir`.
    - `db_impl` path will obtain `DBImpl::directories_.getDbDir()` while others with no access to such `directories_` are obtained on the fly by creating such object `FileSystem::NewDirectory(..)` and manage it by unique pointers to ensure short life time.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10573

Test Plan:
- `make check`
- Passed the repro db_stress command
- For future improvement, since we currently don't assert dir containing CURRENT to be non-nullptr due to https://github.com/facebook/rocksdb/pull/10573#pullrequestreview-1087698899, there is still chances that future developers mistakenly pass down nullptr dir containing CURRENT thus resulting skipped sync dir and cause the bug again. Therefore a smarter test (e.g, such as quoted from ajkr  "(make) unsynced data loss to be dropping files corresponding to unsynced directory entries") is still needed.

Reviewed By: ajkr

Differential Revision: D39005886

Pulled By: hx235

fbshipit-source-id: 336fb9090d0cfa6ca3dd580db86268007dde7f5a
2022-08-29 17:35:21 -07:00
anand76 35cdd3e71e MultiGet async IO across multiple levels (#10535)
Summary:
This PR exploits parallelism in MultiGet across levels. It applies only to the coroutine version of MultiGet. Previously, MultiGet file reads from SST files in the same level were parallelized. With this PR, MultiGet batches with keys distributed across multiple levels are read in parallel. This is accomplished by splitting the keys not present in a level (determined by bloom filtering) into a separate batch, and processing the new batch in parallel with the original batch.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10535

Test Plan:
1. Ensure existing MultiGet unit tests pass, updating them as necessary
2. New unit tests - TODO
3. Run stress test - TODO

No noticeable regression (<1%) without async IO -
Without PR: `multireadrandom :       7.261 micros/op 1101724 ops/sec 60.007 seconds 66110936 operations;  571.6 MB/s (8168992 of 8168992 found)`
With PR: `multireadrandom :       7.305 micros/op 1095167 ops/sec 60.007 seconds 65717936 operations;  568.2 MB/s (8271992 of 8271992 found)`

For a fully cached DB, but with async IO option on, no regression observed (<1%) -
Without PR: `multireadrandom :       5.201 micros/op 1538027 ops/sec 60.005 seconds 92288936 operations;  797.9 MB/s (11540992 of 11540992 found) `
With PR: `multireadrandom :       5.249 micros/op 1524097 ops/sec 60.005 seconds 91452936 operations;  790.7 MB/s (11649992 of 11649992 found) `

Reviewed By: akankshamahajan15

Differential Revision: D38774009

Pulled By: anand1976

fbshipit-source-id: c955e259749f1c091590ade73105b3ee46cd0007
2022-08-19 16:52:52 -07:00
Levi Tamasi 81388b36e0 Add support for wide-column point lookups (#10540)
Summary:
The patch adds a new API `GetEntity` that can be used to perform
wide-column point lookups. It also extends the `Get` code path and
the `MemTable` / `MemTableList` and `Version` / `GetContext` logic
accordingly so that wide-column entities can be served from both
memtables and SSTs. If the result of a lookup is a wide-column entity
(`kTypeWideColumnEntity`), it is passed to the application in deserialized
form; if it is a plain old key-value (`kTypeValue`), it is presented as a
wide-column entity with a single default (anonymous) column.
(In contrast, regular `Get` returns plain old key-values as-is, and
returns the value of the default column for wide-column entities, see
https://github.com/facebook/rocksdb/issues/10483 .)

The result of `GetEntity` is a self-contained `PinnableWideColumns` object.
`PinnableWideColumns` contains a `PinnableSlice`, which either stores the
underlying data in its own buffer or holds on to a cache handle. It also contains
a `WideColumns` instance, which indexes the contents of the `PinnableSlice`,
so applications can access the values of columns efficiently.

There are several pieces of functionality which are currently not supported
for wide-column entities: there is currently no `MultiGetEntity` or wide-column
iterator; also, `Merge` and `GetMergeOperands` are not supported, and there
is no `GetEntity` implementation for read-only and secondary instances.
We plan to implement these in future PRs.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10540

Test Plan: `make check`

Reviewed By: akankshamahajan15

Differential Revision: D38847474

Pulled By: ltamasi

fbshipit-source-id: 42311a34ccdfe88b3775e847a5e2a5296e002b5b
2022-08-19 11:51:12 -07:00
anand76 65814a4ae6 Fix range deletion handling in async MultiGet (#10534)
Summary:
The fix in https://github.com/facebook/rocksdb/issues/10513 was not complete w.r.t range deletion handling. It didn't handle the case where a file with a range tombstone covering a key also overlapped another key in the batch. In that case, ```mget_range``` would be non-empty. However, ```mget_range``` would only have the second key and, therefore, the first key would be skipped when iterating through the range tombstones in ```TableCache::MultiGet```.

Test plan -
1. Add a unit test
2. Run stress tests

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10534

Reviewed By: akankshamahajan15

Differential Revision: D38773880

Pulled By: anand1976

fbshipit-source-id: dae491dbe52e18bbce5179b77b63f20771a66c00
2022-08-17 13:51:39 -07:00
anand76 bf4532eb5c Break TableReader MultiGet into filter and lookup stages (#10432)
Summary:
This PR is the first step in enhancing the coroutines MultiGet to be able to lookup a batch in parallel across levels. By having a separate TableReader function for probing the bloom filters, we can quickly figure out which overlapping keys from a batch are definitely not in the file and can move on to the next level.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10432

Reviewed By: akankshamahajan15

Differential Revision: D38245910

Pulled By: anand1976

fbshipit-source-id: 3d20db2350378c3fe6f086f0c7ba5ff01d7f04de
2022-08-04 12:51:57 -07:00
Zichen Zhu 8860fc902a Support subcmpct using reserved resources for round-robin priority (#10341)
Summary:
Earlier implementation of round-robin priority can only pick one file at a time and disallows parallel compactions within the same level. In this PR, round-robin compaction policy will expand towards more input files with respecting some additional constraints, which are summarized as follows:
 * Constraint 1: We can only pick consecutive files
   - Constraint 1a: When a file is being compacted (or some input files are being compacted after expanding), we cannot choose it and have to stop choosing more files
   - Constraint 1b: When we reach the last file (with the largest keys), we cannot choose more files (the next file will be the first one with small keys)
 * Constraint 2: We should ensure the total compaction bytes (including the overlapped files from the next level) is no more than `mutable_cf_options_.max_compaction_bytes`
 * Constraint 3: We try our best to pick as many files as possible so that the post-compaction level size can be just less than `MaxBytesForLevel(start_level_)`
 * Constraint 4: If trivial move is allowed, we reuse the logic of `TryNonL0TrivialMove()` instead of expanding files with Constraint 3

More details can be found in `LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion()`.

The above optimization accelerates the process of moving the compaction cursor, in which the write-amp can be further reduced. While a large compaction may lead to high write stall, we break this large compaction into several subcompactions **regardless of** the `max_subcompactions` limit.  The number of subcompactions for round-robin compaction priority is determined through the following steps:
* Step 1: Initialized against `max_output_file_limit`, the number of input files in the start level, and also the range size limit `ranges.size()`
* Step 2: Call `AcquireSubcompactionResources()`when max subcompactions is not sufficient, but we may or may not obtain desired resources, additional number of resources is stored in `extra_num_subcompaction_threads_reserved_`). Subcompaction limit is changed and update `num_planned_subcompactions` with `GetSubcompactionLimit()`
* Step 3: Call `ShrinkSubcompactionResources()` to ensure extra resources can be released (extra resources may exist for round-robin compaction when the number of actual number of subcompactions is less than the number of planned subcompactions)

More details can be found in `CompactionJob::AcquireSubcompactionResources()`,`CompactionJob::ShrinkSubcompactionResources()`, and `CompactionJob::ReleaseSubcompactionResources()`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10341

Test Plan: Add `CompactionPriMultipleFilesRoundRobin[1-3]` unit test in `compaction_picker_test.cc` and `RoundRobinSubcompactionsAgainstResources.SubcompactionsUsingResources/[0-4]`, `RoundRobinSubcompactionsAgainstPressureToken.PressureTokenTest/[0-1]` in `db_compaction_test.cc`

Reviewed By: ajkr, hx235

Differential Revision: D37792644

Pulled By: littlepig2013

fbshipit-source-id: 7fecb7c4ffd97b34bbf6e3b760b2c35a772a0657
2022-07-24 11:12:44 -07:00
Gang Liao 056e08d6c4 Enable blob caching for MultiGetBlob in RocksDB (#10272)
Summary:
- [x] Enabled blob caching for MultiGetBlob in RocksDB
- [x] Refactored MultiGetBlob logic and interface in RocksDB
- [x] Cleaned up Version::MultiGetBlob() and moved 'blob'-related code snippets into BlobSource
- [x] Add End-to-end test cases in db_blob_basic_test and also add unit tests in blob_source_test

This task is a part of https://github.com/facebook/rocksdb/issues/10156

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10272

Reviewed By: ltamasi

Differential Revision: D37558112

Pulled By: gangliao

fbshipit-source-id: a73a6a94ffdee0024d5b2a39e6d1c1a7d38664db
2022-06-30 13:24:35 -07:00
zczhu 30141461f9 Add basic kRoundRobin compaction policy (#10107)
Summary:
Add `kRoundRobin` as a compaction priority. The implementation is as follows.

- Define a cursor as the smallest Internal key in the successor of the selected file. Add `vector<InternalKey> compact_cursor_` into `VersionStorageInfo` where each element (`InternalKey`) in `compact_cursor_` represents a cursor. In round-robin compaction policy, we just need to select the first file (assuming files are sorted) and also has the smallest InternalKey larger than/equal to the cursor. After a file is chosen, we create a new `Fsize` vector which puts the selected file is placed at the first position in `temp`, the next cursor is then updated as the smallest InternalKey in successor of the selected file (the above logic is implemented in `SortFileByRoundRobin`).
- After a compaction succeeds, typically `InstallCompactionResults()`, we choose the next cursor for the input level and save it to `edit`. When calling `LogAndApply`, we save the next cursor with its level into some local variable and finally apply the change to `vstorage` in `SaveTo` function.
- Cursors are persist pair by pair (<level, InternalKey>) in `EncodeTo` so that they can be reconstructed when reopening. An empty cursor will not be encoded to MANIFEST

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10107

Test Plan: add unit test (`CompactionPriRoundRobin`) in `compaction_picker_test`, add `kRoundRobin` priority in `CompactionPriTest` from `db_compaction_test`, and add `PersistRoundRobinCompactCursor` in `db_compaction_test`

Reviewed By: ajkr

Differential Revision: D37316037

Pulled By: littlepig2013

fbshipit-source-id: 9f481748190ace416079139044e00df2968fb1ee
2022-06-21 11:56:53 -07:00
Gang Liao deff48bcef Add blob source to retrieve blobs in RocksDB (#10198)
Summary:
There is currently no caching mechanism for blobs, which is not ideal especially when the database resides on remote storage (where we cannot rely on the OS page cache). As part of this task, we would like to make it possible for the application to configure a blob cache.
In this task, we formally introduced the blob source to RocksDB.  BlobSource is a new abstraction layer that provides universal access to blobs, regardless of whether they are in the blob cache, secondary cache, or (remote) storage. Depending on user settings, it always fetch blobs from multi-tier cache and storage with minimal cost.

Note: The new `MultiGetBlob()` implementation is not included in the current PR. To go faster, we aim to create a separate PR for it in parallel!

This PR is a part of https://github.com/facebook/rocksdb/issues/10156

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10198

Reviewed By: ltamasi

Differential Revision: D37294735

Pulled By: gangliao

fbshipit-source-id: 9cb50422d9dd1bc03798501c2778b6c7520c7a1e
2022-06-20 20:58:11 -07:00
anand76 a6691d0f65 Update stats to help users estimate MultiGet async IO impact (#10182)
Summary:
Add a couple of stats to help users estimate the impact of potential MultiGet perf improvements -
1. NUM_LEVEL_READ_PER_MULTIGET - A histogram stat for number of levels that required MultiGet to read from a file
2. MULTIGET_COROUTINE_COUNT - A ticker stat to count the number of times the coroutine version of MultiGetFromSST was used

The NUM_DATA_BLOCKS_READ_PER_LEVEL stat is obsoleted as it doesn't provide useful information for MultiGet optimization.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10182

Reviewed By: akankshamahajan15

Differential Revision: D37213296

Pulled By: anand1976

fbshipit-source-id: 5d2b7708017c0e278578ae4bffac3926f6530efb
2022-06-16 12:12:43 -07:00
Hui Xiao d665afdbf3 Account memory of FileMetaData in global memory limit (#9924)
Summary:
**Context/Summary:**
As revealed by heap profiling, allocation of `FileMetaData` for [newly created file added to a Version](https://github.com/facebook/rocksdb/pull/9924/files#diff-a6aa385940793f95a2c5b39cc670bd440c4547fa54fd44622f756382d5e47e43R774) can consume significant heap memory. This PR is to account that toward our global memory limit based on block cache capacity.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9924

Test Plan:
- Previous `make check` verified there are only 2 places where the memory of  the allocated `FileMetaData` can be released
- New unit test `TEST_P(ChargeFileMetadataTestWithParam, Basic)`
- db bench (CPU cost of `charge_file_metadata` in write and compact)
   - **write micros/op: -0.24%** : `TEST_TMPDIR=/dev/shm/testdb ./db_bench -benchmarks=fillseq -db=$TEST_TMPDIR -charge_file_metadata=1 (remove this option for pre-PR) -disable_auto_compactions=1 -write_buffer_size=100000 -num=4000000 | egrep 'fillseq'`
   - **compact micros/op -0.87%** : `TEST_TMPDIR=/dev/shm/testdb ./db_bench -benchmarks=fillseq -db=$TEST_TMPDIR -charge_file_metadata=1 -disable_auto_compactions=1 -write_buffer_size=100000 -num=4000000 -numdistinct=1000 && ./db_bench -benchmarks=compact -db=$TEST_TMPDIR -use_existing_db=1 -charge_file_metadata=1 -disable_auto_compactions=1 | egrep 'compact'`

table 1 - write

#-run | (pre-PR) avg micros/op | std micros/op | (post-PR)  micros/op | std micros/op | change (%)
-- | -- | -- | -- | -- | --
10 | 3.9711 | 0.264408 | 3.9914 | 0.254563 | 0.5111933721
20 | 3.83905 | 0.0664488 | 3.8251 | 0.0695456 | -0.3633711465
40 | 3.86625 | 0.136669 | 3.8867 | 0.143765 | 0.5289363078
80 | 3.87828 | 0.119007 | 3.86791 | 0.115674 | **-0.2673865734**
160 | 3.87677 | 0.162231 | 3.86739 | 0.16663 | **-0.2419539978**

table 2 - compact

#-run | (pre-PR) avg micros/op | std micros/op | (post-PR)  micros/op | std micros/op | change (%)
-- | -- | -- | -- | -- | --
10 | 2,399,650.00 | 96,375.80 | 2,359,537.00 | 53,243.60 | -1.67
20 | 2,410,480.00 | 89,988.00 | 2,433,580.00 | 91,121.20 | 0.96
40 | 2.41E+06 | 121811 | 2.39E+06 | 131525 | **-0.96**
80 | 2.40E+06 | 134503 | 2.39E+06 | 108799 | **-0.78**

- stress test: `python3 tools/db_crashtest.py blackbox --charge_file_metadata=1  --cache_size=1` killed as normal

Reviewed By: ajkr

Differential Revision: D36055583

Pulled By: hx235

fbshipit-source-id: b60eab94707103cb1322cf815f05810ef0232625
2022-06-14 13:06:40 -07:00
sdong 356f8c5d81 FindObsoleteFiles() to directly check whether candidate files are live (#10040)
Summary:
Right now, in FindObsoleteFiles() we build a list of all live SST files from all existing Versions. This is all done in DB mutex, and is O(m*n) where m is number of versions and n is number of files. In some extereme cases, it can take very long. The list is used to see whether a candidate file still shows up in a version. With this commit, every candidate file is directly check against all the versions for file existance. This operation would be O(m*k) where k is number of candidate files. Since is usually small (except perhaps full compaction in universal compaction), this is usually much faster than the previous solution.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10040

Test Plan: TBD

Reviewed By: riversand963

Differential Revision: D36613391

fbshipit-source-id: 3f13b090f755d9b3ae417faec62cd6e798bac1eb
2022-05-25 12:43:48 -07:00
anand76 57997ddaaf Multi file concurrency in MultiGet using coroutines and async IO (#9968)
Summary:
This PR implements a coroutine version of batched MultiGet in order to concurrently read from multiple SST files in a level using async IO, thus reducing the latency of the MultiGet. The API from the user perspective is still synchronous and single threaded, with the RocksDB part of the processing happening in the context of the caller's thread. In Version::MultiGet, the decision is made whether to call synchronous or coroutine code.

A good way to review this PR is to review the first 4 commits in order - de773b3, 70c2f70, 10b50e1, and 377a597 - before reviewing the rest.

TODO:
1. Figure out how to build it in CircleCI (requires some dependencies to be installed)
2. Do some stress testing with coroutines enabled

No regression in synchronous MultiGet between this branch and main -
```
./db_bench -use_existing_db=true --db=/data/mysql/rocksdb/prefix_scan -benchmarks="readseq,multireadrandom" -key_size=32 -value_size=512 -num=5000000 -batch_size=64 -multiread_batched=true -use_direct_reads=false -duration=60 -ops_between_duration_checks=1 -readonly=true -adaptive_readahead=true -threads=16 -cache_size=10485760000 -async_io=false -multiread_stride=40000 -statistics
```
Branch - ```multireadrandom :       4.025 micros/op 3975111 ops/sec 60.001 seconds 238509056 operations; 2062.3 MB/s (14767808 of 14767808 found)```

Main - ```multireadrandom :       3.987 micros/op 4013216 ops/sec 60.001 seconds 240795392 operations; 2082.1 MB/s (15231040 of 15231040 found)```

More benchmarks in various scenarios are given below. The measurements were taken with ```async_io=false``` (no coroutines) and ```async_io=true``` (use coroutines). For an IO bound workload (with every key requiring an IO), the coroutines version shows a clear benefit, being ~2.6X faster. For CPU bound workloads, the coroutines version has ~6-15% higher CPU utilization, depending on how many keys overlap an SST file.

1. Single thread IO bound workload on remote storage with sparse MultiGet batch keys (~1 key overlap/file) -
No coroutines - ```multireadrandom :     831.774 micros/op 1202 ops/sec 60.001 seconds 72136 operations;    0.6 MB/s (72136 of 72136 found)```
Using coroutines - ```multireadrandom :     318.742 micros/op 3137 ops/sec 60.003 seconds 188248 operations;    1.6 MB/s (188248 of 188248 found)```

2. Single thread CPU bound workload (all data cached) with ~1 key overlap/file -
No coroutines - ```multireadrandom :       4.127 micros/op 242322 ops/sec 60.000 seconds 14539384 operations;  125.7 MB/s (14539384 of 14539384 found)```
Using coroutines - ```multireadrandom :       4.741 micros/op 210935 ops/sec 60.000 seconds 12656176 operations;  109.4 MB/s (12656176 of 12656176 found)```

3. Single thread CPU bound workload with ~2 key overlap/file -
No coroutines - ```multireadrandom :       3.717 micros/op 269000 ops/sec 60.000 seconds 16140024 operations;  139.6 MB/s (16140024 of 16140024 found)```
Using coroutines - ```multireadrandom :       4.146 micros/op 241204 ops/sec 60.000 seconds 14472296 operations;  125.1 MB/s (14472296 of 14472296 found)```

4. CPU bound multi-threaded (16 threads) with ~4 key overlap/file -
No coroutines - ```multireadrandom :       4.534 micros/op 3528792 ops/sec 60.000 seconds 211728728 operations; 1830.7 MB/s (12737024 of 12737024 found) ```
Using coroutines - ```multireadrandom :       4.872 micros/op 3283812 ops/sec 60.000 seconds 197030096 operations; 1703.6 MB/s (12548032 of 12548032 found) ```

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9968

Reviewed By: akankshamahajan15

Differential Revision: D36348563

Pulled By: anand1976

fbshipit-source-id: c0ce85a505fd26ebfbb09786cbd7f25202038696
2022-05-19 15:36:27 -07:00
Jay Zhuang c6d326d3d7 Track SST unique id in MANIFEST and verify (#9990)
Summary:
Start tracking SST unique id in MANIFEST, which is used to verify with
SST properties to make sure the SST file is not overwritten or
misplaced. A DB option `try_verify_sst_unique_id` is introduced to
enable/disable the verification, if enabled, it opens all SST files
during DB-open to read the unique_id from table properties (default is
false), so it's recommended to use it with `max_open_files = -1` to
pre-open the files.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9990

Test Plan: unittests, format-compatible test, mini-crash

Reviewed By: anand1976

Differential Revision: D36381863

Pulled By: jay-zhuang

fbshipit-source-id: 89ea2eb6b35ed3e80ead9c724eb096083eaba63f
2022-05-19 11:04:21 -07:00
sdong 49628c9a83 Use std::numeric_limits<> (#9954)
Summary:
Right now we still don't fully use std::numeric_limits but use a macro, mainly for supporting VS 2013. Right now we only support VS 2017 and up so it is not a problem. The code comment claims that MinGW still needs it. We don't have a CI running MinGW so it's hard to validate. since we now require C++17, it's hard to imagine MinGW would still build RocksDB but doesn't support std::numeric_limits<>.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9954

Test Plan: See CI Runs.

Reviewed By: riversand963

Differential Revision: D36173954

fbshipit-source-id: a35a73af17cdcae20e258cdef57fcf29a50b49e0
2022-05-05 13:08:21 -07:00
Peter Dillinger efd035164b Meta-internal folly integration with F14FastMap (#9546)
Summary:
Especially after updating to C++17, I don't see a compelling case for
*requiring* any folly components in RocksDB. I was able to purge the existing
hard dependencies, and it can be quite difficult to strip out non-trivial components
from folly for use in RocksDB. (The prospect of doing that on F14 has changed
my mind on the best approach here.)

But this change creates an optional integration where we can plug in
components from folly at compile time, starting here with F14FastMap to replace
std::unordered_map when possible (probably no public APIs for example). I have
replaced the biggest CPU users of std::unordered_map with compile-time
pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set.
USE_FOLLY is always set in the Meta-internal buck build, and a simulation of
that is in the Makefile for public CI testing. A full folly build is not needed, but
checking out the full folly repo is much simpler for getting the dependency,
and anything else we might want to optionally integrate in the future.

Some picky details:
* I don't think the distributed mutex stuff is actually used, so it was easy to remove.
* I implemented an alternative to `folly::constexpr_log2` (which is much easier
in C++17 than C++11) so that I could pull out the hard dependencies on
`ConstexprMath.h`
* I had to add noexcept move constructors/operators to some types to make
F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a
macro to make that easier in some common cases.
* Updated Meta-internal buck build to use folly F14Map (always)

No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a
production integration for open source users.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546

Test Plan:
CircleCI tests updated so that a couple of them use folly.

Most internal unit & stress/crash tests updated to use Meta-internal latest folly.
(Note: they should probably use buck but they currently use Makefile.)

Example performance improvement: when filter partitions are pinned in cache,
they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build
a test that exercises that heavily. Build DB with

```
TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters
```

and test with (simultaneous runs with & without folly, ~20 times each to see
convergence)

```
TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache
```

Average ops/s no folly: 26229.2
Average ops/s with folly: 26853.3 (+2.4%)

Reviewed By: ajkr

Differential Revision: D34181736

Pulled By: pdillinger

fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
2022-04-13 07:34:01 -07:00
sdong e03f8a0c12 L0 Subcompaction to trim input files (#9802)
Summary:
When sub compaction is decided for L0->L1 compaction, most of the cases, all L0 files will be involved in all sub compactions. However, it is not always the case. When files are generally (but not strictly) inserted in sequential order, there can be a subset of L0 files invovled. Yet RocksDB always open all those L0 files, and build an iterator, read many of the files' first of last block with expensive readahead. We trim some input files to reduce overhead a little bit.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9802

Test Plan: Add a unit test to cover this case and manually validate the behavior while running the test.

Reviewed By: ajkr

Differential Revision: D35371031

fbshipit-source-id: 701ed7375b5cbe41672e93b38fe8a1503dad08b6
2022-04-06 18:19:19 -07:00
Peter Dillinger cad809978a Fix heap use-after-free race with DropColumnFamily (#9730)
Summary:
Although ColumnFamilySet comments say that DB mutex can be
freed during iteration, as long as you hold a ref while releasing DB
mutex, this is not quite true because UnrefAndTryDelete might delete cfd
right before it is needed to get ->next_ for the next iteration of the
loop.

This change solves the problem by making a wrapper class that makes such
iteration easier while handling the tricky details of UnrefAndTryDelete
on the previous cfd only after getting next_ in operator++.

FreeDeadColumnFamilies should already have been obsolete; this removes
it for good. Similarly, ColumnFamilySet::iterator doesn't need to check
for cfd with 0 refs, because those are immediately deleted.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9730

Test Plan:
was reported with ASAN on unit tests like
DBLogicalBlockSizeCacheTest.CreateColumnFamily (very rare); keep watching

Reviewed By: ltamasi

Differential Revision: D35038143

Pulled By: pdillinger

fbshipit-source-id: 0a5478d5be96c135343a00603711b7df43ae19c9
2022-03-24 13:05:17 -07:00
Yanqin Jin e0c84aa0dc Fix a race condition in WAL tracking causing DB open failure (#9715)
Summary:
There is a race condition if WAL tracking in the MANIFEST is enabled in a database that disables 2PC.

The race condition is between two background flush threads trying to install flush results to the MANIFEST.

Consider an example database with two column families: "default" (cfd0) and "cf1" (cfd1). Initially,
both column families have one mutable (active) memtable whose data backed by 6.log.

1. Trigger a manual flush for "cf1", creating a 7.log
2. Insert another key to "default", and trigger flush for "default", creating 8.log
3. BgFlushThread1 finishes writing 9.sst
4. BgFlushThread2 finishes writing 10.sst

```
Time  BgFlushThread1                                    BgFlushThread2
 |    mutex_.Lock()
 |    precompute min_wal_to_keep as 6
 |    mutex_.Unlock()
 |                                                     mutex_.Lock()
 |                                                     precompute min_wal_to_keep as 6
 |                                                     join MANIFEST write queue and mutex_.Unlock()
 |    write to MANIFEST
 |    mutex_.Lock()
 |    cfd1->log_number = 7
 |    Signal bg_flush_2 and mutex_.Unlock()
 |                                                     wake up and mutex_.Lock()
 |                                                     cfd0->log_number = 8
 |                                                     FindObsoleteFiles() with job_context->log_number == 7
 |                                                     mutex_.Unlock()
 |                                                     PurgeObsoleteFiles() deletes 6.log
 V
```

As shown in the above, BgFlushThread2 thinks that the min wal to keep is 6.log because "cf1" has unflushed data in 6.log (cf1.log_number=6).
Similarly, BgThread1 thinks that min wal to keep is also 6.log because "default" has unflushed data (default.log_number=6).
No WAL deletion will be written to MANIFEST because 6 is equal to `versions_->wals_.min_wal_number_to_keep`,
due to https://github.com/facebook/rocksdb/blob/7.1.fb/db/memtable_list.cc#L513:L514.
The bg flush thread that finishes last will perform file purging. `job_context.log_number` will be evaluated as 7, i.e.
the min wal that contains unflushed data, causing 6.log to be deleted. However, MANIFEST thinks 6.log should still exist.
If you close the db at this point, you won't be able to re-open it if `track_and_verify_wal_in_manifest` is true.

We must handle the case of multiple bg flush threads, and it is difficult for one bg flush thread to know
the correct min wal number until the other bg flush threads have finished committing to the manifest and updated
the `cfd::log_number`.
To fix this issue, we rename an existing variable `min_log_number_to_keep_2pc` to `min_log_number_to_keep`,
and use it to track WAL file deletion in non-2pc mode as well.
This variable is updated only 1) during recovery with mutex held, or 2) in the MANIFEST write thread.
`min_log_number_to_keep` means RocksDB will delete WALs below it, although there may be WALs
above it which are also obsolete. Formally, we will have [min_wal_to_keep, max_obsolete_wal]. During recovery, we
make sure that only WALs above max_obsolete_wal are checked and added back to `alive_log_files_`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9715

Test Plan:
```
make check
```
Also ran stress test below (with asan) to make sure it completes successfully.
```
TEST_TMPDIR=/dev/shm/rocksdb OPT=-g ASAN_OPTIONS=disable_coredump=0 \
CRASH_TEST_EXT_ARGS=--compression_type=zstd SKIP_FORMAT_BUCK_CHECKS=1 \
make J=52 -j52 blackbox_asan_crash_test
```

Reviewed By: ltamasi

Differential Revision: D34984412

Pulled By: riversand963

fbshipit-source-id: c7b21a8d84751bb55ea79c9f387103d21b231005
2022-03-23 19:41:31 -07:00
Yanqin Jin 3bd150c442 Print information about all column families when using ldb (#9719)
Summary:
Before this PR, the following command prints only the default column
family's information in the end:
```
ldb --db=. --hex manifest_dump --verbose
```

We should print all column families instead.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9719

Test Plan:
`make check` makes sure nothing breaks.

Generate a DB, use the above command to verify all column families are
printed.

Reviewed By: akankshamahajan15

Differential Revision: D34992453

Pulled By: riversand963

fbshipit-source-id: de1d38c4539cd89f74e1a6240ad7a6e2416bf198
2022-03-22 20:29:01 -07:00
Hui Xiao 443d8ef094 Fix PinSelf() read-after-free in DB::GetMergeOperands() (#9507)
Summary:
**Context:**
Running the new test `DBMergeOperandTest.MergeOperandReadAfterFreeBug` prior to this fix surfaces the read-after-free bug of PinSef() as below:
```
READ of size 8 at 0x60400002529d thread T0
    https://github.com/facebook/rocksdb/issues/5 0x7f199a in rocksdb::PinnableSlice::PinSelf(rocksdb::Slice const&) include/rocksdb/slice.h:171
    https://github.com/facebook/rocksdb/issues/6 0x7f199a in rocksdb::DBImpl::GetImpl(rocksdb::ReadOptions const&, rocksdb::Slice const&, rocksdb::DBImpl::GetImplOptions&) db/db_impl/db_impl.cc:1919
    https://github.com/facebook/rocksdb/issues/7 0x540d63 in rocksdb::DBImpl::GetMergeOperands(rocksdb::ReadOptions const&, rocksdb::ColumnFamilyHandle*, rocksdb::Slice const&, rocksdb::PinnableSlice*, rocksdb::GetMergeOperandsOptions*, int*) db/db_impl/db_impl.h:203

freed by thread T0 here:
    https://github.com/facebook/rocksdb/issues/3 0x1191399 in rocksdb::cache_entry_roles_detail::RegisteredDeleter<rocksdb::Block, (rocksdb::CacheEntryRole)0>::Delete(rocksdb::Slice const&, void*) cache/cache_entry_roles.h:99
    https://github.com/facebook/rocksdb/issues/4 0x719348 in rocksdb::LRUHandle::Free() cache/lru_cache.h:205
    https://github.com/facebook/rocksdb/issues/5 0x71047f in rocksdb::LRUCacheShard::Release(rocksdb::Cache::Handle*, bool) cache/lru_cache.cc:547
    https://github.com/facebook/rocksdb/issues/6 0xa78f0a in rocksdb::Cleanable::DoCleanup() include/rocksdb/cleanable.h:60
    https://github.com/facebook/rocksdb/issues/7 0xa78f0a in rocksdb::Cleanable::Reset() include/rocksdb/cleanable.h:38
    https://github.com/facebook/rocksdb/issues/8 0xa78f0a in rocksdb::PinnedIteratorsManager::ReleasePinnedData() db/pinned_iterators_manager.h:71
    https://github.com/facebook/rocksdb/issues/9 0xd0c21b in rocksdb::PinnedIteratorsManager::~PinnedIteratorsManager() db/pinned_iterators_manager.h:24
    https://github.com/facebook/rocksdb/issues/10 0xd0c21b in rocksdb::Version::Get(rocksdb::ReadOptions const&, rocksdb::LookupKey const&, rocksdb::PinnableSlice*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*, rocksdb::Status*, rocksdb::MergeContext*, unsigned long*, bool*, bool*, unsigned long*, rocksdb::ReadCallback*, bool*, bool) db/pinned_iterators_manager.h:22
    https://github.com/facebook/rocksdb/issues/11 0x7f0fdf in rocksdb::DBImpl::GetImpl(rocksdb::ReadOptions const&, rocksdb::Slice const&, rocksdb::DBImpl::GetImplOptions&) db/db_impl/db_impl.cc:1886
    https://github.com/facebook/rocksdb/issues/12 0x540d63 in rocksdb::DBImpl::GetMergeOperands(rocksdb::ReadOptions const&, rocksdb::ColumnFamilyHandle*, rocksdb::Slice const&, rocksdb::PinnableSlice*, rocksdb::GetMergeOperandsOptions*, int*) db/db_impl/db_impl.h:203

previously allocated by thread T0 here:
    https://github.com/facebook/rocksdb/issues/1 0x1239896 in rocksdb::AllocateBlock(unsigned long, **rocksdb::MemoryAllocator*)** memory/memory_allocator.h:35
    https://github.com/facebook/rocksdb/issues/2 0x1239896 in rocksdb::BlockFetcher::CopyBufferToHeapBuf() table/block_fetcher.cc:171
    https://github.com/facebook/rocksdb/issues/3 0x1239896 in rocksdb::BlockFetcher::GetBlockContents() table/block_fetcher.cc:206
    https://github.com/facebook/rocksdb/issues/4 0x122eae5 in rocksdb::BlockFetcher::ReadBlockContents() table/block_fetcher.cc:325
    https://github.com/facebook/rocksdb/issues/5 0x11b1f45 in rocksdb::Status rocksdb::BlockBasedTable::MaybeReadBlockAndLoadToCache<rocksdb::Block>(rocksdb::FilePrefetchBuffer*, rocksdb::ReadOptions const&, rocksdb::BlockHandle const&, rocksdb::UncompressionDict const&, bool, rocksdb::CachableEntry<rocksdb::Block>*, rocksdb::BlockType, rocksdb::GetContext*, rocksdb::BlockCacheLookupContext*, rocksdb::BlockContents*) const table/block_based/block_based_table_reader.cc:1503
```
Here is the analysis:
- We have [PinnedIteratorsManager](https://github.com/facebook/rocksdb/blob/6.28.fb/db/version_set.cc#L1980) with `Cleanable` capability in our `Version::Get()` path. It's responsible for managing the life-time of pinned iterator and invoking registered cleanup functions during its own destruction.
  - For example in case above, the merge operands's clean-up gets associated with this manger in [GetContext::push_operand](https://github.com/facebook/rocksdb/blob/6.28.fb/table/get_context.cc#L405). During PinnedIteratorsManager's [destruction](https://github.com/facebook/rocksdb/blob/6.28.fb/db/pinned_iterators_manager.h#L67), the release function associated with those merge operand data is invoked.
**And that's what we see in "freed by thread T955 here" in ASAN.**
- Bug 🐛: `PinnedIteratorsManager` is local to `Version::Get()`  while the data of merge operands need to outlive `Version::Get` and stay till they get [PinSelf()](https://github.com/facebook/rocksdb/blob/6.28.fb/db/db_impl/db_impl.cc#L1905), **which is the read-after-free in ASAN.**
  - This bug is likely to be an overlook of `PinnedIteratorsManager` when developing the API `DB::GetMergeOperands` cuz the current logic works fine with the existing case of getting the *merged value* where the operands do not need to live that long.
- This bug was not surfaced much (even in its unit test) due to the release function associated with the merge operands (which are actually blocks put in cache as you can see in `BlockBasedTable::MaybeReadBlockAndLoadToCache` **in "previously allocated by" in ASAN report**) is a cache entry deleter.
The deleter will call `Cache::Release()` which, for LRU cache, won't immediately deallocate the block based on LRU policy [unless the cache is full or being instructed to force erase](https://github.com/facebook/rocksdb/blob/6.28.fb/cache/lru_cache.cc#L521-L531)
  - `DBMergeOperandTest.MergeOperandReadAfterFreeBug` makes the cache extremely small to force cache full.

**Summary:**
- Fix the bug by align `PinnedIteratorsManager`'s lifetime with the merge operands

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9507

Test Plan:
- New test `DBMergeOperandTest.MergeOperandReadAfterFreeBug`
- db bench on read path
  - Setup (LSM tree with several levels, cache the whole db to avoid read IO, warm cache with readseq to avoid read IO): `TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks="fillrandom,readseq  -num=1000000 -cache_size=100000000  -write_buffer_size=10000 -statistics=1 -max_bytes_for_level_base=10000 -level0_file_num_compaction_trigger=1``TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks="readrandom" -num=1000000 -cache_size=100000000 `
  - Actual command run (run 20-run for 20 times and then average the 20-run's average micros/op)
     - `for j in {1..20}; do (for i in {1..20}; do rm -rf /dev/shm/rocksdb/ && TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks="fillrandom,readseq,readrandom" -num=1000000 -cache_size=100000000  -write_buffer_size=10000 -statistics=1 -max_bytes_for_level_base=10000 -level0_file_num_compaction_trigger=1 | egrep 'readrandom'; done > rr_output_pre.txt && (awk '{sum+=$3; sum_sqrt+=$3^2}END{print sum/20, sqrt(sum_sqrt/20-(sum/20)^2)}' rr_output_pre.txt) >> rr_output_pre_2.txt); done`
  - **Result: Pre-change: 3.79193 micros/op;   Post-change: 3.79528 micros/op (+0.09%)**

(pre-change)sorted avg micros/op of each 20-run | std of micros/op of each 20-run | (post-change) sorted avg micros/op of each 20-run | std of micros/op of each 20-run
-- | -- | -- | --
3.58355 | 0.265209 | 3.48715 | 0.382076
3.58845 | 0.519927 | 3.5832 | 0.382726
3.66415 | 0.452097 | 3.677 | 0.563831
3.68495 | 0.430897 | 3.68405 | 0.495355
3.70295 | 0.482893 | 3.68465 | 0.431438
3.719 | 0.463806 | 3.71945 | 0.457157
3.7393 | 0.453423 | 3.72795 | 0.538604
3.7806 | 0.527613 | 3.75075 | 0.444509
3.7817 | 0.426704 | 3.7683 | 0.468065
3.809 | 0.381033 | 3.8086 | 0.557378
3.80985 | 0.466011 | 3.81805 | 0.524833
3.8165 | 0.500351 | 3.83405 | 0.529339
3.8479 | 0.430326 | 3.86285 | 0.44831
3.85125 | 0.434108 | 3.8717 | 0.544098
3.8556 | 0.524602 | 3.895 | 0.411679
3.8656 | 0.476383 | 3.90965 | 0.566636
3.8911 | 0.488477 | 3.92735 | 0.608038
3.898 | 0.493978 | 3.9439 | 0.524511
3.97235 | 0.515008 | 3.9623 | 0.477416
3.9768 | 0.519993 | 3.98965 | 0.521481

- CI

Reviewed By: ajkr

Differential Revision: D34030519

Pulled By: hx235

fbshipit-source-id: a99ac585c11704c5ed93af033cb29ba0a7b16ae8
2022-02-15 12:25:18 -08:00
Levi Tamasi 073ac54739 Log blob file space amp and expose it via the rocksdb.blob-stats DB property (#9538)
Summary:
Extend the periodic statistics in the info log with the total amount of garbage
in blob files and the space amplification pertaining to blob files, where the
latter is defined as `total_blob_file_size / (total_blob_file_size - total_blob_garbage_size)`.
Also expose the space amp via the `rocksdb.blob-stats` DB property.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9538

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D34126855

Pulled By: ltamasi

fbshipit-source-id: 3153e7a0fe0eca440322db273f4deaabaccc51b2
2022-02-10 12:42:11 -08:00
Levi Tamasi 320d9a8e8a Use a sorted vector instead of a map to store blob file metadata (#9526)
Summary:
The patch replaces `std::map` with a sorted `std::vector` for
`VersionStorageInfo::blob_files_` and preallocates the space
for the `vector` before saving the `BlobFileMetaData` into the
new `VersionStorageInfo` in `VersionBuilder::Rep::SaveBlobFilesTo`.
These changes reduce the time the DB mutex is held while
saving new `Version`s, and using a sorted `vector` also makes
lookups faster thanks to better memory locality.

In addition, the patch introduces helper methods
`VersionStorageInfo::GetBlobFileMetaData` and
`VersionStorageInfo::GetBlobFileMetaDataLB` that can be used by
clients to perform lookups in the `vector`, and does some general
cleanup in the parts of code where blob file metadata are used.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9526

Test Plan:
Ran `make check` and the crash test script for a while.

Performance was tested using a load-optimized benchmark (`fillseq` with vector memtable, no WAL) and small file sizes so that a significant number of files are produced:

```
numactl --interleave=all ./db_bench --benchmarks=fillseq --allow_concurrent_memtable_write=false --level0_file_num_compaction_trigger=4 --level0_slowdown_writes_trigger=20 --level0_stop_writes_trigger=30 --max_background_jobs=8 --max_write_buffer_number=8 --db=/data/ltamasi-dbbench --wal_dir=/data/ltamasi-dbbench --num=800000000 --num_levels=8 --key_size=20 --value_size=400 --block_size=8192 --cache_size=51539607552 --cache_numshardbits=6 --compression_max_dict_bytes=0 --compression_ratio=0.5 --compression_type=lz4 --bytes_per_sync=8388608 --cache_index_and_filter_blocks=1 --cache_high_pri_pool_ratio=0.5 --benchmark_write_rate_limit=0 --write_buffer_size=16777216 --target_file_size_base=16777216 --max_bytes_for_level_base=67108864 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --statistics=0 --stats_per_interval=1 --stats_interval_seconds=20 --histogram=1 --memtablerep=skip_list --bloom_bits=10 --open_files=-1 --subcompactions=1 --compaction_style=0 --min_level_to_compress=3 --level_compaction_dynamic_level_bytes=true --pin_l0_filter_and_index_blocks_in_cache=1 --soft_pending_compaction_bytes_limit=167503724544 --hard_pending_compaction_bytes_limit=335007449088 --min_level_to_compress=0 --use_existing_db=0 --sync=0 --threads=1 --memtablerep=vector --allow_concurrent_memtable_write=false --disable_wal=1 --enable_blob_files=1 --blob_file_size=16777216 --min_blob_size=0 --blob_compression_type=lz4 --enable_blob_garbage_collection=1 --seed=<some value>
```

Final statistics before the patch:

```
Cumulative writes: 0 writes, 700M keys, 0 commit groups, 0.0 writes per commit group, ingest: 284.62 GB, 121.27 MB/s
Interval writes: 0 writes, 334K keys, 0 commit groups, 0.0 writes per commit group, ingest: 139.28 MB, 72.46 MB/s
```

With the patch:

```
Cumulative writes: 0 writes, 760M keys, 0 commit groups, 0.0 writes per commit group, ingest: 308.66 GB, 131.52 MB/s
Interval writes: 0 writes, 445K keys, 0 commit groups, 0.0 writes per commit group, ingest: 185.35 MB, 93.15 MB/s
```

Total time to complete the benchmark is 2611 seconds with the patch, down from 2986 secs.

Reviewed By: riversand963

Differential Revision: D34082728

Pulled By: ltamasi

fbshipit-source-id: fc598abf676dce436734d06bb9d2d99a26a004fc
2022-02-09 12:36:43 -08:00
Levi Tamasi 0cc0543893 Mitigate the overhead of building the hash of file locations (#9504)
Summary:
The patch builds on the refactoring done in https://github.com/facebook/rocksdb/issues/9494
and improves the performance of building the hash of file
locations in `VersionStorageInfo` in two ways. First, the hash
building is moved from `AddFile` (which is called under the DB mutex)
to a separate post-processing step done as part of `PrepareForVersionAppend`
(during which the mutex is *not* held). Second, the space necessary
for the hash is preallocated to prevent costly reallocation/rehashing
operations. These changes mitigate the overhead of the file location hash,
which can be significant with certain workloads where the baseline CPU usage
is low (see https://github.com/facebook/rocksdb/issues/9351,
which is a workload where keys are sorted, WAL is turned
off, the vector memtable implementation is used, and there are lots of small
SST files).

Fixes https://github.com/facebook/rocksdb/issues/9351

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9504

Test Plan:
`make check`

```
numactl --interleave=all ./db_bench --benchmarks=fillseq --allow_concurrent_memtable_write=false --level0_file_num_compaction_trigger=4 --level0_slowdown_writes_trigger=20 --level0_stop_writes_trigger=30 --max_background_jobs=8 --max_write_buffer_number=8 --db=/data/ltamasi-dbbench --wal_dir=/data/ltamasi-dbbench --num=800000000 --num_levels=8 --key_size=20 --value_size=400 --block_size=8192 --cache_size=51539607552 --cache_numshardbits=6 --compression_max_dict_bytes=0 --compression_ratio=0.5 --compression_type=lz4 --bytes_per_sync=8388608 --cache_index_and_filter_blocks=1 --cache_high_pri_pool_ratio=0.5 --benchmark_write_rate_limit=0 --write_buffer_size=16777216 --target_file_size_base=16777216 --max_bytes_for_level_base=67108864 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --statistics=0 --stats_per_interval=1 --stats_interval_seconds=20 --histogram=1 --bloom_bits=10 --open_files=-1 --subcompactions=1 --compaction_style=0 --level_compaction_dynamic_level_bytes=true --pin_l0_filter_and_index_blocks_in_cache=1 --soft_pending_compaction_bytes_limit=167503724544 --hard_pending_compaction_bytes_limit=335007449088 --min_level_to_compress=0 --use_existing_db=0 --sync=0 --threads=1 --memtablerep=vector --disable_wal=1 --seed=<some_seed>
```

Final statistics before this patch:
```
Cumulative writes: 0 writes, 697M keys, 0 commit groups, 0.0 writes per commit group, ingest: 283.25 GB, 241.08 MB/s
Interval writes: 0 writes, 1264K keys, 0 commit groups, 0.0 writes per commit group, ingest: 525.69 MB, 176.67 MB/s
```

With the patch:
```
Cumulative writes: 0 writes, 759M keys, 0 commit groups, 0.0 writes per commit group, ingest: 308.57 GB, 262.63 MB/s
Interval writes: 0 writes, 1555K keys, 0 commit groups, 0.0 writes per commit group, ingest: 646.61 MB, 215.11 MB/s
```

Reviewed By: riversand963

Differential Revision: D34014734

Pulled By: ltamasi

fbshipit-source-id: acb2703677451d5ccaa7e9d950844b33d240695b
2022-02-07 09:17:14 -08:00
Levi Tamasi 42e0751b3a Clean up VersionStorageInfo a bit (#9494)
Summary:
The patch does some cleanup in and around `VersionStorageInfo`:
* Renames the method `PrepareApply` to `PrepareAppend` in `Version`
to make it clear that it is to be called before appending the `Version` to
`VersionSet` (via `AppendVersion`), not before applying any `VersionEdit`s.
* Introduces a helper method `VersionStorageInfo::PrepareForVersionAppend`
(called by `Version::PrepareAppend`) that encapsulates the population of the
various derived data structures in `VersionStorageInfo`, and turns the
methods computing the derived structures (`UpdateNumNonEmptyLevels`,
`CalculateBaseBytes` etc.) into private helpers.
* Changes `Version::PrepareAppend` so it only calls `UpdateAccumulatedStats`
if the `update_stats` flag is set. (Earlier, this was checked by the callee.)
Related to this, it also moves the call to `ComputeCompensatedSizes` to
`VersionStorageInfo::PrepareForVersionAppend`.
* Updates and cleans up `version_builder_test`, `version_set_test`, and
`compaction_picker_test` so `PrepareForVersionAppend` is called anytime
a new `VersionStorageInfo` is set up or saved. This cleanup also involves
splitting `VersionStorageInfoTest.MaxBytesForLevelDynamic`
into multiple smaller test cases.
* Fixes up a bunch of comments that were outdated or just plain incorrect.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9494

Test Plan: Ran `make check` and the crash test script for a while.

Reviewed By: riversand963

Differential Revision: D33971666

Pulled By: ltamasi

fbshipit-source-id: fda52faac7783041126e4f8dec0fe01bdcadf65a
2022-02-04 08:19:20 -08:00
Youngjae Lee 3dfee770c6 Remove obsolete function declaration (#8724)
Summary:
Function `Version::UpdateFilesByCompactionPri()` is never called and not implemented.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8724

Reviewed By: ajkr

Differential Revision: D30643943

Pulled By: riversand963

fbshipit-source-id: 174b2d9a2a42e286222909a035cc74a7b5602335
2022-01-07 18:06:10 -08:00
Andrew Kryczka b860a42158 Recover to exact latest seqno of data committed to MANIFEST (#9305)
Summary:
The LastSequence field in the MANIFEST file is the baseline seqno for a recovered DB. Recovering WAL entries might cause the recovered DB's seqno to advance above this baseline, but the recovered DB will never use a smaller seqno.

Before this PR, we were writing the DB's seqno at the time of LogAndApply() as the LastSequence value. This works in the sense that it is a large enough baseline for the recovered DB that it'll never overwrite any records in existing SST files. At the same time, it's arbitrarily larger than what's needed. This behavior comes from LevelDB, where there was no tracking of largest seqno in an SST file.

Now we know the largest seqno of newly written SST files, so we can write an exact value in LastSequence that actually reflects the largest seqno in any file referred to by the MANIFEST. This is primarily useful for correctness testing with unsynced data loss, where the recovered DB's seqno needs to indicate what records were recovered.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9305

Test Plan:
- https://github.com/facebook/rocksdb/issues/9338 adds crash-recovery correctness testing coverage for WAL disabled use cases
- https://github.com/facebook/rocksdb/issues/9357 will extend that testing to cover file ingestion
- Added assertion at end of LogAndApply() for `VersionSet::descriptor_last_sequence_` consistency with files
- Manually tested upgrade/downgrade compatibility with a custom crash test that randomly picks between a `db_stress` built with and without this PR (for old code it must run with `-disable_wal=0`)

Reviewed By: riversand963

Differential Revision: D33182770

Pulled By: ajkr

fbshipit-source-id: 0bfafaf685f347cc8cb0e1d62e0186340a738f7d
2022-01-05 16:02:21 -08:00
Peter Dillinger 0050a73a4f New stable, fixed-length cache keys (#9126)
Summary:
This change standardizes on a new 16-byte cache key format for
block cache (incl compressed and secondary) and persistent cache (but
not table cache and row cache).

The goal is a really fast cache key with practically ideal stability and
uniqueness properties without external dependencies (e.g. from FileSystem).
A fixed key size of 16 bytes should enable future optimizations to the
concurrent hash table for block cache, which is a heavy CPU user /
bottleneck, but there appears to be measurable performance improvement
even with no changes to LRUCache.

This change replaces a lot of disjointed and ugly code handling cache
keys with calls to a simple, clean new internal API (cache_key.h).
(Preserving the old cache key logic under an option would be very ugly
and likely negate the performance gain of the new approach. Complete
replacement carries some inherent risk, but I think that's acceptable
with sufficient analysis and testing.)

The scheme for encoding new cache keys is complicated but explained
in cache_key.cc.

Also: EndianSwapValue is moved to math.h to be next to other bit
operations. (Explains some new include "math.h".) ReverseBits operation
added and unit tests added to hash_test for both.

Fixes https://github.com/facebook/rocksdb/issues/7405 (presuming a root cause)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9126

Test Plan:
### Basic correctness
Several tests needed updates to work with the new functionality, mostly
because we are no longer relying on filesystem for stable cache keys
so table builders & readers need more context info to agree on cache
keys. This functionality is so core, a huge number of existing tests
exercise the cache key functionality.

### Performance
Create db with
`TEST_TMPDIR=/dev/shm ./db_bench -bloom_bits=10 -benchmarks=fillrandom -num=3000000 -partition_index_and_filters`
And test performance with
`TEST_TMPDIR=/dev/shm ./db_bench -readonly -use_existing_db -bloom_bits=10 -benchmarks=readrandom -num=3000000 -duration=30 -cache_index_and_filter_blocks -cache_size=250000 -threads=4`
using DEBUG_LEVEL=0 and simultaneous before & after runs.
Before ops/sec, avg over 100 runs: 121924
After ops/sec, avg over 100 runs: 125385 (+2.8%)

### Collision probability
I have built a tool, ./cache_bench -stress_cache_key to broadly simulate host-wide cache activity
over many months, by making some pessimistic simplifying assumptions:
* Every generated file has a cache entry for every byte offset in the file (contiguous range of cache keys)
* All of every file is cached for its entire lifetime

We use a simple table with skewed address assignment and replacement on address collision
to simulate files coming & going, with quite a variance (super-Poisson) in ages. Some output
with `./cache_bench -stress_cache_key -sck_keep_bits=40`:

```
Total cache or DBs size: 32TiB  Writing 925.926 MiB/s or 76.2939TiB/day
Multiply by 9.22337e+18 to correct for simulation losses (but still assume whole file cached)
```

These come from default settings of 2.5M files per day of 32 MB each, and
`-sck_keep_bits=40` means that to represent a single file, we are only keeping 40 bits of
the 128-bit cache key.  With file size of 2\*\*25 contiguous keys (pessimistic), our simulation
is about 2\*\*(128-40-25) or about 9 billion billion times more prone to collision than reality.

More default assumptions, relatively pessimistic:
* 100 DBs in same process (doesn't matter much)
* Re-open DB in same process (new session ID related to old session ID) on average
every 100 files generated
* Restart process (all new session IDs unrelated to old) 24 times per day

After enough data, we get a result at the end:

```
(keep 40 bits)  17 collisions after 2 x 90 days, est 10.5882 days between (9.76592e+19 corrected)
```

If we believe the (pessimistic) simulation and the mathematical generalization, we would need to run a billion machines all for 97 billion days to expect a cache key collision. To help verify that our generalization ("corrected") is robust, we can make our simulation more precise with `-sck_keep_bits=41` and `42`, which takes more running time to get enough data:

```
(keep 41 bits)  16 collisions after 4 x 90 days, est 22.5 days between (1.03763e+20 corrected)
(keep 42 bits)  19 collisions after 10 x 90 days, est 47.3684 days between (1.09224e+20 corrected)
```

The generalized prediction still holds. With the `-sck_randomize` option, we can see that we are beating "random" cache keys (except offsets still non-randomized) by a modest amount (roughly 20x less collision prone than random), which should make us reasonably comfortable even in "degenerate" cases:

```
197 collisions after 1 x 90 days, est 0.456853 days between (4.21372e+18 corrected)
```

I've run other tests to validate other conditions behave as expected, never behaving "worse than random" unless we start chopping off structured data.

Reviewed By: zhichao-cao

Differential Revision: D33171746

Pulled By: pdillinger

fbshipit-source-id: f16a57e369ed37be5e7e33525ace848d0537c88f
2021-12-16 17:15:13 -08:00
Levi Tamasi dc5de45af8 Support readahead during compaction for blob files (#9187)
Summary:
The patch adds a new BlobDB configuration option `blob_compaction_readahead_size`
that can be used to enable prefetching data from blob files during compaction.
This is important when using storage with higher latencies like HDDs or remote filesystems.
If enabled, prefetching is used for all cases when blobs are read during compaction,
namely garbage collection, compaction filters (when the existing value has to be read from
a blob file), and `Merge` (when the value of the base `Put` is stored in a blob file).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9187

Test Plan: Ran `make check` and the stress/crash test.

Reviewed By: riversand963

Differential Revision: D32565512

Pulled By: ltamasi

fbshipit-source-id: 87be9cebc3aa01cc227bec6b5f64d827b8164f5d
2021-11-19 17:53:47 -08:00
Levi Tamasi 081722780b Refactor the detailed consistency checks and the SST saving logic in VersionBuilder (#9099)
Summary:
The patch refactors the parts of `VersionBuilder` that deal with SST file
comparisons. Specifically, it makes the following changes:
* Turns `NewestFirstBySeqNo` and `BySmallestKey` from free-standing
functions into function objects. Note: `BySmallestKey` has a pointer to the
`InternalKeyComparator`, while `NewestFirstBySeqNo` is completely
stateless.
* Eliminates the wrapper `FileComparator`, which was essentially an
unnecessary DIY virtual function call mechanism.
* Refactors `CheckConsistencyDetails` and `SaveSSTFilesTo` using helper
function templates that take comparator/checker function objects. Using
static polymorphism eliminates the need to make runtime decisions about
which comparator to use.
* Extends some error messages returned by the consistency checks and
makes them more uniform.
* Removes some incomplete/redundant consistency checks from `VersionBuilder`
and `FilePicker`.
* Improves const correctness in several places.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9099

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D32027503

Pulled By: ltamasi

fbshipit-source-id: 621326ae41f4f55f7ad6a91abbd6e666d5c7857c
2021-11-03 11:52:47 -07:00
sdong a2b9be42b6 Try to start TTL earlier with kMinOverlappingRatio is used (#8749)
Summary:
Right now, when options.ttl is set, compactions are triggered around the time when TTL is reached. This might cause extra compactions which are often bursty. This commit tries to mitigate it by picking those files earlier in normal compaction picking process. This is only implemented using kMinOverlappingRatio with Leveled compaction as it is the default value and it is more complicated to change other styles.

When a file is aged more than ttl/2, RocksDB starts to boost the compaction priority of files in normal compaction picking process, and hope by the time TTL is reached, very few extra compaction is needed.

In order for this to work, another change is made: during a compaction, if an output level file is older than ttl/2, cut output files based on original boundary (if it is not in the last level). This is to make sure that after an old file is moved to the next level, and new data is merged from the upper level, the new data falling into this range isn't reset with old timestamp. Without this change, in many cases, most files from one level will keep having old timestamp, even if they have newer data and we stuck in it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8749

Test Plan: Add a unit test to test the boosting logic. Will add a unit test to test it end-to-end.

Reviewed By: jay-zhuang

Differential Revision: D30735261

fbshipit-source-id: 503c2d89250b22911eb99e72b379be154de3428e
2021-11-01 14:36:31 -07:00
Peter Dillinger 3ffb3baa0b Add (Live)FileStorageInfo API (#8968)
Summary:
New classes FileStorageInfo and LiveFileStorageInfo and
'experimental' function DB::GetLiveFilesStorageInfo, which is intended
to largely replace several fragmented DB functions needed to create
checkpoints and backups.

This function is now used to create checkpoints and backups, because
it fixes many (probably not all) of the prior complexities of checkpoint
not having atomic access to DB metadata. This also ensures strong
functional test coverage of the new API. Specifically, much of the old
CheckpointImpl::CreateCustomCheckpoint has been migrated to and
updated in DBImpl::GetLiveFilesStorageInfo, with the former now
calling the latter.

Also, the class FileStorageInfo in metadata.h compatibly replaces
BackupFileInfo and serves as a new base class for SstFileMetaData.
Some old fields of SstFileMetaData are still provided (for now) but
deprecated.

Although FileStorageInfo::directory is accurate when using db_paths
and/or cf_paths, these have never been supported by Checkpoint
nor BackupEngine and still are not. This change does now detect
these cases and return NotSupported when appropriate. (More work
needed for support.)

Somehow this change broke ProgressCallbackDuringBackup, but
the progress_callback logic was dubious to begin with because it
would call the callback based on copy buffer size, not size actually
copied. Logic and test updated to track size actually copied
per-thread.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8968

Test Plan:
tests updated.
DB::GetLiveFilesStorageInfo mostly tested by use in CheckpointImpl.
DBTest.SnapshotFiles updated to also test GetLiveFilesStorageInfo,
including reading the data after DB close.
Added CheckpointTest.CheckpointWithDbPath (NotSupported).

Reviewed By: siying

Differential Revision: D31242045

Pulled By: pdillinger

fbshipit-source-id: b183d1ce9799e220daaefd6b3b5365d98de676c0
2021-10-16 10:04:32 -07:00
Levi Tamasi 3e1bf771a3 Make it possible to force the garbage collection of the oldest blob files (#8994)
Summary:
The current BlobDB garbage collection logic works by relocating the valid
blobs from the oldest blob files as they are encountered during compaction,
and cleaning up blob files once they contain nothing but garbage. However,
with sufficiently skewed workloads, it is theoretically possible to end up in a
situation when few or no compactions get scheduled for the SST files that contain
references to the oldest blob files, which can lead to increased space amp due
to the lack of GC.

In order to efficiently handle such workloads, the patch adds a new BlobDB
configuration option called `blob_garbage_collection_force_threshold`,
which signals to BlobDB to schedule targeted compactions for the SST files
that keep alive the oldest batch of blob files if the overall ratio of garbage in
the given blob files meets the threshold *and* all the given blob files are
eligible for GC based on `blob_garbage_collection_age_cutoff`. (For example,
if the new option is set to 0.9, targeted compactions will get scheduled if the
sum of garbage bytes meets or exceeds 90% of the sum of total bytes in the
oldest blob files, assuming all affected blob files are below the age-based cutoff.)
The net result of these targeted compactions is that the valid blobs in the oldest
blob files are relocated and the oldest blob files themselves cleaned up (since
*all* SST files that rely on them get compacted away).

These targeted compactions are similar to periodic compactions in the sense
that they force certain SST files that otherwise would not get picked up to undergo
compaction and also in the sense that instead of merging files from multiple levels,
they target a single file. (Note: such compactions might still include neighboring files
from the same level due to the need of having a "clean cut" boundary but they never
include any files from any other level.)

This functionality is currently only supported with the leveled compaction style
and is inactive by default (since the default value is set to 1.0, i.e. 100%).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8994

Test Plan: Ran `make check` and tested using `db_bench` and the stress/crash tests.

Reviewed By: riversand963

Differential Revision: D31489850

Pulled By: ltamasi

fbshipit-source-id: 44057d511726a0e2a03c5d9313d7511b3f0c4eab
2021-10-11 18:03:01 -07:00
Yanqin Jin b92cef2d1d Sort per-file blob read requests by offset (#8953)
Summary:
`RandomAccessFileReader::MultiRead()` tries to merge requests in direct IO, assuming input IO requests are
sorted by offsets.

Add a test in direct IO mode.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8953

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D31183546

Pulled By: riversand963

fbshipit-source-id: 5d043ec68e2daa47a3149066150afd41ee3d73e6
2021-09-24 22:14:30 -07:00
Yanqin Jin b512f4bc76 Batch blob read IO for MultiGet (#8699)
Summary:
In batched `MultiGet()`, RocksDB batches blob read IO and uses `RandomAccessFileReader::MultiRead()`
to read the blobs instead of issuing multiple `Read()`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8699

Test Plan:
```
make check
```

Reviewed By: ltamasi

Differential Revision: D31030861

Pulled By: riversand963

fbshipit-source-id: a0df6060cbfd54cff9515a4eee08807b1dbcb0c8
2021-09-17 19:23:13 -07:00
Levi Tamasi 306b779957 Use GetBlobFileSize instead of GetTotalBlobBytes in DB properties (#8902)
Summary:
The patch adjusts the definition of BlobDB's DB properties a bit by
switching to `GetBlobFileSize` from `GetTotalBlobBytes`. The
difference is that the value returned by `GetBlobFileSize` includes
the blob file header and footer as well, and thus matches the on-disk
size of blob files. In addition, the patch removes the `Version` number
from the `blob_stats` property, and updates/extends the unit tests a little.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8902

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D30859542

Pulled By: ltamasi

fbshipit-source-id: e3426d2d567bd1bd8c8636abdafaafa0743c854c
2021-09-13 10:47:16 -07:00
Zhiyi Zhang 0cb0fc6fd3 Add DB properties for BlobDB (#8734)
Summary:
RocksDB exposes certain internal statistics via the DB property interface.
However, there are currently no properties related to BlobDB.

For starters, we would like to add the following BlobDB properties:
`rocksdb.num-blob-files`: number of blob files in the current Version (kind of like `num-files-at-level` but note this is not per level, since blob files are not part of the LSM tree).
`rocksdb.blob-stats`: this could return the total number and size of all blob files, and potentially also the total amount of garbage (in bytes) in the blob files in the current Version.
`rocksdb.total-blob-file-size`: the total size of all blob files (as a blob counterpart for `total-sst-file-size`) of all Versions.
`rocksdb.live-blob-file-size`: the total size of all blob files in the current Version.
`rocksdb.estimate-live-data-size`: this is actually an existing property that we can extend so it considers blob files as well. When it comes to blobs, we actually have an exact value for live bytes. Namely, live bytes can be computed simply as total bytes minus garbage bytes, summed over the entire set of blob files in the Version.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8734

Test Plan:
```
➜  rocksdb git:(new_feature_blobDB_properties) ./db_blob_basic_test
[==========] Running 16 tests from 2 test cases.
[----------] Global test environment set-up.
[----------] 10 tests from DBBlobBasicTest
[ RUN      ] DBBlobBasicTest.GetBlob
[       OK ] DBBlobBasicTest.GetBlob (12 ms)
[ RUN      ] DBBlobBasicTest.MultiGetBlobs
[       OK ] DBBlobBasicTest.MultiGetBlobs (11 ms)
[ RUN      ] DBBlobBasicTest.GetBlob_CorruptIndex
[       OK ] DBBlobBasicTest.GetBlob_CorruptIndex (10 ms)
[ RUN      ] DBBlobBasicTest.GetBlob_InlinedTTLIndex
[       OK ] DBBlobBasicTest.GetBlob_InlinedTTLIndex (12 ms)
[ RUN      ] DBBlobBasicTest.GetBlob_IndexWithInvalidFileNumber
[       OK ] DBBlobBasicTest.GetBlob_IndexWithInvalidFileNumber (9 ms)
[ RUN      ] DBBlobBasicTest.GenerateIOTracing
[       OK ] DBBlobBasicTest.GenerateIOTracing (11 ms)
[ RUN      ] DBBlobBasicTest.BestEffortsRecovery_MissingNewestBlobFile
[       OK ] DBBlobBasicTest.BestEffortsRecovery_MissingNewestBlobFile (13 ms)
[ RUN      ] DBBlobBasicTest.GetMergeBlobWithPut
[       OK ] DBBlobBasicTest.GetMergeBlobWithPut (11 ms)
[ RUN      ] DBBlobBasicTest.MultiGetMergeBlobWithPut
[       OK ] DBBlobBasicTest.MultiGetMergeBlobWithPut (14 ms)
[ RUN      ] DBBlobBasicTest.BlobDBProperties
[       OK ] DBBlobBasicTest.BlobDBProperties (21 ms)
[----------] 10 tests from DBBlobBasicTest (124 ms total)

[----------] 6 tests from DBBlobBasicTest/DBBlobBasicIOErrorTest
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.GetBlob_IOError/0
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.GetBlob_IOError/0 (12 ms)
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.GetBlob_IOError/1
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.GetBlob_IOError/1 (10 ms)
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.MultiGetBlobs_IOError/0
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.MultiGetBlobs_IOError/0 (10 ms)
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.MultiGetBlobs_IOError/1
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.MultiGetBlobs_IOError/1 (10 ms)
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.CompactionFilterReadBlob_IOError/0
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.CompactionFilterReadBlob_IOError/0 (1011 ms)
[ RUN      ] DBBlobBasicTest/DBBlobBasicIOErrorTest.CompactionFilterReadBlob_IOError/1
[       OK ] DBBlobBasicTest/DBBlobBasicIOErrorTest.CompactionFilterReadBlob_IOError/1 (1013 ms)
[----------] 6 tests from DBBlobBasicTest/DBBlobBasicIOErrorTest (2066 ms total)

[----------] Global test environment tear-down
[==========] 16 tests from 2 test cases ran. (2190 ms total)
[  PASSED  ] 16 tests.
```

Reviewed By: ltamasi

Differential Revision: D30690849

Pulled By: Zhiyi-Zhang

fbshipit-source-id: a7567319487ad76bd1a2e24bf143afdbbd9e4346
2021-09-08 12:22:04 -07:00
Baptiste Lemaire c521a9ab2b Retire superfluous functions introduced in earlier mempurge PRs. (#8558)
Summary:
The main challenge to make the memtable garbage collection prototype (nicknamed `mempurge`) was to not get rid of WAL files that contain unflushed (but mempurged) data. That was successfully guaranteed by not writing the VersionEdit to the MANIFEST file after a successful mempurge.
By not writing VersionEdits to the `MANIFEST` file after a succesful mempurge operation, we do not change the earliest log file number that contains unflushed data: `cfd->GetLogNumber()` (`cfd->SetLogNumber()` is only called in `VersionSet::ProcessManifestWrites`). As a result, a number of functions introduced earlier just for the mempurge operation are not obscolete/redundant. (e.g.: `FlushJob::ExtractEarliestLogFileNumber`), and this PR aims at cleaning up all these now-unnecessary functions. In particular, we no longer need to store the earliest log file number in the `MemTable` struct itself. This PR therefore also reverts the `MemTable` struct to its original form.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8558

Test Plan: Already included in `db_flush_test.cc`.

Reviewed By: anand1976

Differential Revision: D29764351

Pulled By: bjlemaire

fbshipit-source-id: 0f43b260fa270251862512f397d3f24ee62e8437
2021-07-22 18:29:13 -07:00
Baptiste Lemaire 206845c057 Mempurge support for wal (#8528)
Summary:
In this PR, `mempurge` is made compatible with the Write Ahead Log: in case of recovery, the DB is now capable of recovering the data that was "mempurged" and kept in the `imm()` list of immutable memtables.
The twist was to add a uint64_t to the `memtable` struct to store the number of the earliest log file containing entries from the `memtable`. When a `Flush` operation is replaced with a `MemPurge`, the `VersionEdit` (which usually contains the new min log file number to pick up for recovery and the level 0 file path of the newly created SST file) is no longer appended to the manifest log, and every time the `deleteWal` method is called, a check is made on the list of immutable memtables.
This PR also includes a unit test that verifies that no data is lost upon Reopening of the database when the mempurge feature is activated. This extensive unit test includes two column families, with valid data contained in the imm() at time of "crash"/reopening (recovery).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8528

Reviewed By: pdillinger

Differential Revision: D29701097

Pulled By: bjlemaire

fbshipit-source-id: 072a900fb6ccc1edcf5eef6caf88f3060238edf9
2021-07-15 17:49:13 -07:00
longlijian ac3f3f3719 Eliminate compiler complaining, which the return type of the function… (#8498)
Summary:
… should be uint64_t.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8498

Reviewed By: jay-zhuang

Differential Revision: D29605064

Pulled By: ajkr

fbshipit-source-id: e431448ac9d8a37ae83679c4cc5732e29fe49de4
2021-07-08 10:09:05 -07:00
Levi Tamasi d44ef2ed4d Remove obsolete method VersionSet::VerifyCompactionFileConsistency (#8449)
Summary:
`VersionSet::VerifyCompactionFileConsistency` was superseded by the LSM tree
consistency checks introduced in https://github.com/facebook/rocksdb/pull/6901,
which are more comprehensive, more efficient, and are performed unconditionally
even in release builds.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8449

Test Plan: `make check`

Reviewed By: ajkr

Differential Revision: D29337441

Pulled By: ltamasi

fbshipit-source-id: a05324f88e3400e27e6a00406c878a6276e0c9cc
2021-06-23 13:28:34 -07:00
mrambacher d5bd0039b9 Rename ImmutableOptions variables (#8409)
Summary:
This is the next part of the ImmutableOptions cleanup.  After changing the use of ImmutableCFOptions to ImmutableOptions, there were places in the code that had did something like "ImmutableOptions* immutable_cf_options", where "cf" referred to the "old" type.

This change simply renames the variables to match the current type.  No new functionality is introduced.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8409

Reviewed By: pdillinger

Differential Revision: D29166248

Pulled By: mrambacher

fbshipit-source-id: 96de97f8e743f5c5160f02246e3ed8269556dc6f
2021-06-16 16:51:38 -07:00
Zhichao Cao f44e69c64a Use DbSessionId as cache key prefix when secondary cache is enabled (#8360)
Summary:
Currently, we either use the file system inode or a monotonically incrementing runtime ID as the block cache key prefix. However, if we use a monotonically incrementing runtime ID (in the case that the file system does not support inode id generation), in some cases, it cannot ensure uniqueness (e.g., we have secondary cache migrated from host to host). We use DbSessionID (20 bytes) + current file number (at most 10 bytes) as the new cache block key prefix when the secondary cache is enabled. So can accommodate scenarios such as transfer of cache state across hosts.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8360

Test Plan: add the test to lru_cache_test

Reviewed By: pdillinger

Differential Revision: D29006215

Pulled By: zhichao-cao

fbshipit-source-id: 6cff686b38d83904667a2bd39923cd030df16814
2021-06-10 11:02:43 -07:00
mrambacher 8948dc8524 Make ImmutableOptions struct that inherits from ImmutableCFOptions and ImmutableDBOptions (#8262)
Summary:
The ImmutableCFOptions contained a bunch of fields that belonged to the ImmutableDBOptions.  This change cleans that up by introducing an ImmutableOptions struct.  Following the pattern of Options struct, this class inherits from the DB and CFOption structs (of the Immutable form).

Only one structural change (the ImmutableCFOptions::fs was changed to a shared_ptr from a raw one) is in this PR.  All of the other changes involve moving the member variables from the ImmutableCFOptions into the ImmutableOptions and changing member variables or function parameters as required for compilation purposes.

Follow-on PRs may do a further clean-up of the code, such as renaming variables (such as "ImmutableOptions cf_options") and potentially eliminating un-needed function parameters (there is no longer a need to pass both an ImmutableDBOptions and an ImmutableOptions to a function).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8262

Reviewed By: pdillinger

Differential Revision: D28226540

Pulled By: mrambacher

fbshipit-source-id: 18ae71eadc879dedbe38b1eb8e6f9ff5c7147dbf
2021-05-05 14:00:17 -07:00
Yanqin Jin b0e20194ea Handle blob files when options.best_efforts_recovery is true (#8180)
Summary:
If `options.best_efforts_recovery == true`, RocksDB currently tolerates missing table files and recovers to the latest version without missing table files (not considering WAL). It is necessary to handle blob files as well to make the feature more complete.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8180

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D27840556

Pulled By: riversand963

fbshipit-source-id: 041685d0dc2e7779ac4f0374c07a8a327704aa5e
2021-04-19 11:56:14 -07:00
mrambacher 3dff28cf9b Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)
Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>.  The shared ptr has some performance degradation on certain hardware classes.

For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere.  For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it.  The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.

There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold.  In those cases, the shared pointer was preserved.

Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:

6.17: readrandom   :      28.046 micros/op 854902 ops/sec;   61.3 MB/s (355999 of 355999 found)
6.18: readrandom   :      32.615 micros/op 735306 ops/sec;   52.7 MB/s (290999 of 290999 found)
PR: readrandom   :      27.500 micros/op 871909 ops/sec;   62.5 MB/s (367999 of 367999 found)

(Note that the times for 6.18 are prior to revert of the SystemClock).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033

Reviewed By: pdillinger

Differential Revision: D27014563

Pulled By: mrambacher

fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
2021-03-15 04:34:11 -07:00