rocksdb/db/obsolete_files_test.cc

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Fix race condition causing double deletion of ssts Summary: Possible interleaved execution of background compaction thread calling `FindObsoleteFiles (no full scan) / PurgeObsoleteFiles` and user thread calling `FindObsoleteFiles (full scan) / PurgeObsoleteFiles` can lead to race condition on which RocksDB attempts to delete a file twice. The second attempt will fail and return `IO error`. This may occur to other files, but this PR targets sst. Also add a unit test to verify that this PR fixes the issue. The newly added unit test `obsolete_files_test` has a test case for this scenario, implemented in `ObsoleteFilesTest#RaceForObsoleteFileDeletion`. `TestSyncPoint`s are used to coordinate the interleaving the `user_thread` and background compaction thread. They execute as follows ``` timeline user_thread background_compaction thread t1 | FindObsoleteFiles(full_scan=false) t2 | FindObsoleteFiles(full_scan=true) t3 | PurgeObsoleteFiles t4 | PurgeObsoleteFiles V ``` When `user_thread` invokes `FindObsoleteFiles` with full scan, it collects ALL files in RocksDB directory, including the ones that background compaction thread have collected in its job context. Then `user_thread` will see an IO error when trying to delete these files in `PurgeObsoleteFiles` because background compaction thread has already deleted the file in `PurgeObsoleteFiles`. To fix this, we make RocksDB remember which (SST) files have been found by threads after calling `FindObsoleteFiles` (see `DBImpl#files_grabbed_for_purge_`). Therefore, when another thread calls `FindObsoleteFiles` with full scan, it will not collect such files. ajkr could you take a look and comment? Thanks! Closes https://github.com/facebook/rocksdb/pull/3638 Differential Revision: D7384372 Pulled By: riversand963 fbshipit-source-id: 01489516d60012e722ee65a80e1449e589ce26d3
2018-03-28 17:23:31 +00:00
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#ifndef ROCKSDB_LITE
#include <stdlib.h>
#include <map>
#include <string>
#include <vector>
#include "db/db_impl.h"
#include "db/version_set.h"
#include "db/write_batch_internal.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/transaction_log.h"
#include "util/filename.h"
#include "util/string_util.h"
#include "util/sync_point.h"
#include "util/testharness.h"
#include "util/testutil.h"
using std::cerr;
using std::cout;
using std::endl;
using std::flush;
namespace rocksdb {
class ObsoleteFilesTest : public testing::Test {
public:
std::string dbname_;
Options options_;
DB* db_;
Env* env_;
int numlevels_;
ObsoleteFilesTest() {
db_ = nullptr;
env_ = Env::Default();
// Trigger compaction when the number of level 0 files reaches 2.
options_.level0_file_num_compaction_trigger = 2;
options_.disable_auto_compactions = false;
options_.delete_obsolete_files_period_micros = 0; // always do full purge
options_.enable_thread_tracking = true;
options_.write_buffer_size = 1024*1024*1000;
options_.target_file_size_base = 1024*1024*1000;
options_.max_bytes_for_level_base = 1024*1024*1000;
options_.WAL_ttl_seconds = 300; // Used to test log files
options_.WAL_size_limit_MB = 1024; // Used to test log files
dbname_ = test::PerThreadDBPath("obsolete_files_test");
Fix race condition causing double deletion of ssts Summary: Possible interleaved execution of background compaction thread calling `FindObsoleteFiles (no full scan) / PurgeObsoleteFiles` and user thread calling `FindObsoleteFiles (full scan) / PurgeObsoleteFiles` can lead to race condition on which RocksDB attempts to delete a file twice. The second attempt will fail and return `IO error`. This may occur to other files, but this PR targets sst. Also add a unit test to verify that this PR fixes the issue. The newly added unit test `obsolete_files_test` has a test case for this scenario, implemented in `ObsoleteFilesTest#RaceForObsoleteFileDeletion`. `TestSyncPoint`s are used to coordinate the interleaving the `user_thread` and background compaction thread. They execute as follows ``` timeline user_thread background_compaction thread t1 | FindObsoleteFiles(full_scan=false) t2 | FindObsoleteFiles(full_scan=true) t3 | PurgeObsoleteFiles t4 | PurgeObsoleteFiles V ``` When `user_thread` invokes `FindObsoleteFiles` with full scan, it collects ALL files in RocksDB directory, including the ones that background compaction thread have collected in its job context. Then `user_thread` will see an IO error when trying to delete these files in `PurgeObsoleteFiles` because background compaction thread has already deleted the file in `PurgeObsoleteFiles`. To fix this, we make RocksDB remember which (SST) files have been found by threads after calling `FindObsoleteFiles` (see `DBImpl#files_grabbed_for_purge_`). Therefore, when another thread calls `FindObsoleteFiles` with full scan, it will not collect such files. ajkr could you take a look and comment? Thanks! Closes https://github.com/facebook/rocksdb/pull/3638 Differential Revision: D7384372 Pulled By: riversand963 fbshipit-source-id: 01489516d60012e722ee65a80e1449e589ce26d3
2018-03-28 17:23:31 +00:00
options_.wal_dir = dbname_ + "/wal_files";
// clean up all the files that might have been there before
std::vector<std::string> old_files;
env_->GetChildren(dbname_, &old_files);
for (auto file : old_files) {
env_->DeleteFile(dbname_ + "/" + file);
}
env_->GetChildren(options_.wal_dir, &old_files);
for (auto file : old_files) {
env_->DeleteFile(options_.wal_dir + "/" + file);
}
DestroyDB(dbname_, options_);
numlevels_ = 7;
EXPECT_OK(ReopenDB(true));
}
Status ReopenDB(bool create) {
delete db_;
if (create) {
DestroyDB(dbname_, options_);
}
db_ = nullptr;
options_.create_if_missing = create;
return DB::Open(options_, dbname_, &db_);
}
void CloseDB() {
delete db_;
db_ = nullptr;
}
void AddKeys(int numkeys, int startkey) {
WriteOptions options;
options.sync = false;
for (int i = startkey; i < (numkeys + startkey) ; i++) {
std::string temp = ToString(i);
Slice key(temp);
Slice value(temp);
ASSERT_OK(db_->Put(options, key, value));
}
}
int numKeysInLevels(
std::vector<LiveFileMetaData> &metadata,
std::vector<int> *keysperlevel = nullptr) {
if (keysperlevel != nullptr) {
keysperlevel->resize(numlevels_);
}
int numKeys = 0;
for (size_t i = 0; i < metadata.size(); i++) {
int startkey = atoi(metadata[i].smallestkey.c_str());
int endkey = atoi(metadata[i].largestkey.c_str());
int numkeysinfile = (endkey - startkey + 1);
numKeys += numkeysinfile;
if (keysperlevel != nullptr) {
(*keysperlevel)[(int)metadata[i].level] += numkeysinfile;
}
fprintf(stderr, "level %d name %s smallest %s largest %s\n",
metadata[i].level, metadata[i].name.c_str(),
metadata[i].smallestkey.c_str(),
metadata[i].largestkey.c_str());
}
return numKeys;
}
void createLevel0Files(int numFiles, int numKeysPerFile) {
int startKey = 0;
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
for (int i = 0; i < numFiles; i++) {
AddKeys(numKeysPerFile, startKey);
startKey += numKeysPerFile;
ASSERT_OK(dbi->TEST_FlushMemTable());
ASSERT_OK(dbi->TEST_WaitForFlushMemTable());
}
}
void CheckFileTypeCounts(std::string& dir,
int required_log,
int required_sst,
int required_manifest) {
std::vector<std::string> filenames;
env_->GetChildren(dir, &filenames);
int log_cnt = 0, sst_cnt = 0, manifest_cnt = 0;
for (auto file : filenames) {
uint64_t number;
FileType type;
if (ParseFileName(file, &number, &type)) {
log_cnt += (type == kLogFile);
sst_cnt += (type == kTableFile);
manifest_cnt += (type == kDescriptorFile);
}
}
ASSERT_EQ(required_log, log_cnt);
ASSERT_EQ(required_sst, sst_cnt);
ASSERT_EQ(required_manifest, manifest_cnt);
}
};
TEST_F(ObsoleteFilesTest, RaceForObsoleteFileDeletion) {
createLevel0Files(2, 50000);
CheckFileTypeCounts(options_.wal_dir, 1, 0, 0);
SyncPoint::GetInstance()->LoadDependency({
{"DBImpl::BackgroundCallCompaction:FoundObsoleteFiles",
"ObsoleteFilesTest::RaceForObsoleteFileDeletion:1"},
{"DBImpl::BackgroundCallCompaction:PurgedObsoleteFiles",
"ObsoleteFilesTest::RaceForObsoleteFileDeletion:2"},
});
SyncPoint::GetInstance()->SetCallBack(
"DBImpl::DeleteObsoleteFileImpl:AfterDeletion", [&](void* arg) {
Status* p_status = reinterpret_cast<Status*>(arg);
ASSERT_TRUE(p_status->ok());
});
SyncPoint::GetInstance()->SetCallBack(
"DBImpl::CloseHelper:PendingPurgeFinished", [&](void* arg) {
std::vector<uint64_t>* files_grabbed_for_purge_ptr =
reinterpret_cast<std::vector<uint64_t>*>(arg);
ASSERT_TRUE(files_grabbed_for_purge_ptr->empty());
});
SyncPoint::GetInstance()->EnableProcessing();
DBImpl* dbi = reinterpret_cast<DBImpl*>(db_);
port::Thread user_thread([&]() {
JobContext jobCxt(0);
TEST_SYNC_POINT("ObsoleteFilesTest::RaceForObsoleteFileDeletion:1");
dbi->TEST_LockMutex();
dbi->FindObsoleteFiles(&jobCxt,
true /* force=true */, false /* no_full_scan=false */);
dbi->TEST_UnlockMutex();
TEST_SYNC_POINT("ObsoleteFilesTest::RaceForObsoleteFileDeletion:2");
dbi->PurgeObsoleteFiles(jobCxt);
jobCxt.Clean();
});
user_thread.join();
CloseDB();
}
TEST_F(ObsoleteFilesTest, DeleteObsoleteOptionsFile) {
createLevel0Files(2, 50000);
CheckFileTypeCounts(options_.wal_dir, 1, 0, 0);
std::vector<uint64_t> optsfiles_nums;
std::vector<bool> optsfiles_keep;
SyncPoint::GetInstance()->SetCallBack(
"DBImpl::PurgeObsoleteFiles:CheckOptionsFiles:1", [&](void* arg) {
optsfiles_nums.push_back(*reinterpret_cast<uint64_t*>(arg));
});
SyncPoint::GetInstance()->SetCallBack(
"DBImpl::PurgeObsoleteFiles:CheckOptionsFiles:2", [&](void* arg) {
optsfiles_keep.push_back(*reinterpret_cast<bool*>(arg));
});
SyncPoint::GetInstance()->EnableProcessing();
DBImpl* dbi = static_cast<DBImpl*>(db_);
ASSERT_OK(dbi->DisableFileDeletions());
for (int i = 0; i != 4; ++i) {
if (i % 2) {
ASSERT_OK(dbi->SetOptions(dbi->DefaultColumnFamily(),
{{"paranoid_file_checks", "false"}}));
} else {
ASSERT_OK(dbi->SetOptions(dbi->DefaultColumnFamily(),
{{"paranoid_file_checks", "true"}}));
}
}
ASSERT_OK(dbi->EnableFileDeletions(true /* force */));
ASSERT_EQ(optsfiles_nums.size(), optsfiles_keep.size());
CloseDB();
std::vector<std::string> files;
int opts_file_count = 0;
ASSERT_OK(env_->GetChildren(dbname_, &files));
for (const auto& file : files) {
uint64_t file_num;
Slice dummy_info_log_name_prefix;
FileType type;
WalFileType log_type;
if (ParseFileName(file, &file_num, dummy_info_log_name_prefix, &type,
&log_type) &&
type == kOptionsFile) {
opts_file_count++;
}
}
ASSERT_EQ(2, opts_file_count);
}
Fix race condition causing double deletion of ssts Summary: Possible interleaved execution of background compaction thread calling `FindObsoleteFiles (no full scan) / PurgeObsoleteFiles` and user thread calling `FindObsoleteFiles (full scan) / PurgeObsoleteFiles` can lead to race condition on which RocksDB attempts to delete a file twice. The second attempt will fail and return `IO error`. This may occur to other files, but this PR targets sst. Also add a unit test to verify that this PR fixes the issue. The newly added unit test `obsolete_files_test` has a test case for this scenario, implemented in `ObsoleteFilesTest#RaceForObsoleteFileDeletion`. `TestSyncPoint`s are used to coordinate the interleaving the `user_thread` and background compaction thread. They execute as follows ``` timeline user_thread background_compaction thread t1 | FindObsoleteFiles(full_scan=false) t2 | FindObsoleteFiles(full_scan=true) t3 | PurgeObsoleteFiles t4 | PurgeObsoleteFiles V ``` When `user_thread` invokes `FindObsoleteFiles` with full scan, it collects ALL files in RocksDB directory, including the ones that background compaction thread have collected in its job context. Then `user_thread` will see an IO error when trying to delete these files in `PurgeObsoleteFiles` because background compaction thread has already deleted the file in `PurgeObsoleteFiles`. To fix this, we make RocksDB remember which (SST) files have been found by threads after calling `FindObsoleteFiles` (see `DBImpl#files_grabbed_for_purge_`). Therefore, when another thread calls `FindObsoleteFiles` with full scan, it will not collect such files. ajkr could you take a look and comment? Thanks! Closes https://github.com/facebook/rocksdb/pull/3638 Differential Revision: D7384372 Pulled By: riversand963 fbshipit-source-id: 01489516d60012e722ee65a80e1449e589ce26d3
2018-03-28 17:23:31 +00:00
} //namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
#else
#include <stdio.h>
int main(int /*argc*/, char** /*argv*/) {
Fix race condition causing double deletion of ssts Summary: Possible interleaved execution of background compaction thread calling `FindObsoleteFiles (no full scan) / PurgeObsoleteFiles` and user thread calling `FindObsoleteFiles (full scan) / PurgeObsoleteFiles` can lead to race condition on which RocksDB attempts to delete a file twice. The second attempt will fail and return `IO error`. This may occur to other files, but this PR targets sst. Also add a unit test to verify that this PR fixes the issue. The newly added unit test `obsolete_files_test` has a test case for this scenario, implemented in `ObsoleteFilesTest#RaceForObsoleteFileDeletion`. `TestSyncPoint`s are used to coordinate the interleaving the `user_thread` and background compaction thread. They execute as follows ``` timeline user_thread background_compaction thread t1 | FindObsoleteFiles(full_scan=false) t2 | FindObsoleteFiles(full_scan=true) t3 | PurgeObsoleteFiles t4 | PurgeObsoleteFiles V ``` When `user_thread` invokes `FindObsoleteFiles` with full scan, it collects ALL files in RocksDB directory, including the ones that background compaction thread have collected in its job context. Then `user_thread` will see an IO error when trying to delete these files in `PurgeObsoleteFiles` because background compaction thread has already deleted the file in `PurgeObsoleteFiles`. To fix this, we make RocksDB remember which (SST) files have been found by threads after calling `FindObsoleteFiles` (see `DBImpl#files_grabbed_for_purge_`). Therefore, when another thread calls `FindObsoleteFiles` with full scan, it will not collect such files. ajkr could you take a look and comment? Thanks! Closes https://github.com/facebook/rocksdb/pull/3638 Differential Revision: D7384372 Pulled By: riversand963 fbshipit-source-id: 01489516d60012e722ee65a80e1449e589ce26d3
2018-03-28 17:23:31 +00:00
fprintf(stderr,
"SKIPPED as DBImpl::DeleteFile is not supported in ROCKSDB_LITE\n");
return 0;
}
#endif // !ROCKSDB_LITE