e34087c524
Summary: This is a simplified version of https://github.com/facebook/rocksdb/issues/13096, which called for a way to hook into long-running loops completely within RocksDB to change their thread priority (or similar). The current prime hook point is `DBIter::FindNextUserEntryInternal` likely because of iterating over tombstones. This is implemented using the weak symbol hack for ease of back-porting/patching, and while we get to know potential future requirements better for integration into the public API. (Consider potential relationships to `Env::GetThreadStatusUpdater()` and `TransactionDBMutexFactory`.) Pull Request resolved: https://github.com/facebook/rocksdb/pull/13103 Test Plan: Performance validated with db_bench and DEBUG_LEVEL=0: `./db_bench --benchmarks=fillseq,deleterandom,readseq[-X100] --value_size=1 --num=1000000` No consistent difference seen; variances likely in how DB / executable / memory were laid out. ``` With an empty hook: readseq [AVG 100 runs] : 1753018 (± 8850) ops/sec; 28.4 (± 0.1) MB/sec readseq [MEDIAN 100 runs] : 1763746 ops/sec; 28.6 MB/sec (recompile) readseq [AVG 100 runs] : 1789019 (± 10260) ops/sec; 29.0 (± 0.2) MB/sec readseq [MEDIAN 100 runs] : 1801849 ops/sec; 29.2 MB/sec Base: readseq [AVG 100 runs] : 1772196 (± 8240) ops/sec; 28.7 (± 0.1) MB/sec readseq [MEDIAN 100 runs] : 1780453 ops/sec; 28.9 MB/sec (recompile) readseq [AVG 100 runs] : 1777637 (± 7613) ops/sec; 28.8 (± 0.1) MB/sec readseq [MEDIAN 100 runs] : 1786657 ops/sec; 29.0 MB/sec With a functional hook (count number of calls into it): readseq [AVG 100 runs] : 1796733 (± 8854) ops/sec; 29.1 (± 0.1) MB/sec readseq [MEDIAN 100 runs] : 1804690 ops/sec; 29.3 MB/sec RocksDbThreadYield: 126915800 (recompile) readseq [AVG 100 runs] : 1775371 (± 10529) ops/sec; 28.8 (± 0.2) MB/sec readseq [MEDIAN 100 runs] : 1789046 ops/sec; 29.0 MB/sec RocksDbThreadYield: 126977000 Base: readseq [AVG 100 runs] : 1773071 (± 10657) ops/sec; 28.7 (± 0.2) MB/sec readseq [MEDIAN 100 runs] : 1783414 ops/sec; 28.9 MB/sec (recompile) readseq [AVG 100 runs] : 1750852 (± 10184) ops/sec; 28.4 (± 0.2) MB/sec readseq [MEDIAN 100 runs] : 1763587 ops/sec; 28.6 MB/sec ``` Reviewed By: george-reynya Differential Revision: D65235379 Pulled By: pdillinger fbshipit-source-id: 7829e4cc25a56d4c1801b8adf9c7f7aa49ab7aca |
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README.md
RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast key-value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it especially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/main/examples
See the github wiki for more explanation.
The public interface is in include/. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.
License
RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.