A library that provides an embeddable, persistent key-value store for fast storage.
cd85439632
Summary: Context: [Rapid thread creation and deletion](https://github.com/facebook/rocksdb/blob/6.27.fb/utilities/transactions/write_prepared_transaction_test.cc#L439-L444) in `SnapshotConcurrentAccessTest.SnapshotConcurrentAcces` inside a [potentially big loop](https://github.com/facebook/rocksdb/blob/6.27.fb/utilities/transactions/write_prepared_transaction_test.cc#L1238-L1248) can lead to heavy-loading the system with many threads due to delay in actually cleaning up thread's resource in the kernel sometime. We ran into some [flaky failure](https://app.circleci.com/pipelines/github/facebook/rocksdb/10383/workflows/136f1005-80a9-4515-aee9-fe36ac6462a1/jobs/253289) in CI and reproduced it by below: - Command ``` Added `ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();` like https://github.com/facebook/rocksdb/pull/9276 DEBUG_LEVEL=2 make -j56 write_prepared_transaction_test GTEST_CATCH_EXCEPTIONS=0 ~/gtest-parallel/gtest-parallel -r 200 -w 200 ./write_prepared_transaction_test --gtest_filter=TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 ``` - Stack, where `write_prepared_transaction_test.cc:442` in `https://github.com/facebook/rocksdb/issues/9` points to thread creation ``` [ RUN ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 ....terminate called after throwing an instance of 'std::system_error' what(): Resource temporarily unavailable Received signal 6 (Aborted) #0 /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38) [0x7fc114f39438] ... https://github.com/facebook/rocksdb/issues/7 /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0xb8e73) [0x7fc1158a5e73] ?? ??:0 https://github.com/facebook/rocksdb/issues/8 ./write_prepared_transaction_test() [0x4ca86c] std:🧵:thread<rocksdb::WritePreparedTransactionTestBase::SnapshotConcurrentAccessTestInternal(rocksdb::WritePreparedTxnDB*, std::vector<unsigned long, std::allocator<unsigned long> > const&, std::vector<unsigned long, std::allocator<unsigned long> const&, rocksdb::WritePreparedTxnDB::CommitEntry&, unsigned long&, unsigned long, unsigned long, unsigned long, unsigned long)::{lambda()https://github.com/facebook/rocksdb/issues/1}>(rocksdb::WritePreparedTransactionTestBase::SnapshotConcurrentAccessTestInternal(rocksdb::WritePreparedTxnDB*, s d::vector<unsigned long, std::allocator<unsigned long> > const&, std::vector<unsigned long, std::allocator<unsigned long> > const&, rocksdb::WritePreparedTxnDB::CommitEntry&, unsigned long&, unsigned long, unsigned long, unsigned long, unsigned long)::{l mbda()https://github.com/facebook/rocksdb/issues/1}&&) /usr/include/c++/5/thread:137 (discriminator 4) https://github.com/facebook/rocksdb/issues/9 ./write_prepared_transaction_test() [0x4bb80c] rocksdb::WritePreparedTransactionTestBase::SnapshotConcurrentAccessTestInternal(rocksdb::WritePreparedTxnDB*, std::vector<unsigned long, std::allocator<unsigned long> > const&, std::vector<unsigned long, std::allocator<unsigned long> > const&, rocksdb::W itePreparedTxnDB::CommitEntry&, unsigned long&, unsigned long, unsigned long, unsigned long, unsigned long) /home/circleci/project/utilities/transactions/write_prepared_transaction_test.cc:442 https://github.com/facebook/rocksdb/issues/10 ./write_prepared_transaction_test() [0x4407b6] rocksdb::SnapshotConcurrentAccessTest_SnapshotConcurrentAccess_Test::TestBody() /home/circleci/project/utilities/transactions/write_prepared_transaction_test.cc:1244 ... [109/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 returned/aborted with exit code -6 (34462 ms) ``` - Move thread 2's work into current thread to avoid half of the thread creation cuz there is no difference in doing so. We expect this can make the thread-creation error less often, even though we can't gurantee it from happening again. Considering this is a trivial change with positive impact, it's still worth landing and monitor if it's enough to solve the problem in reality. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9281 Test Plan: Before the change, repeating the test 200 times with 200 workers failed `~/gtest-parallel/gtest-parallel -r 200 -w 200 ./write_prepared_transaction_test --gtest_filter=TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1` ``` [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from TwoWriteQueues/SnapshotConcurrentAccessTest [ RUN ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 ..unknown file: Failure C++ exception with description "Resource temporarily unavailable" thrown in the test body. [ FAILED ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1, where GetParam() = (false, true, 1, 0, 1, 20) (11882 ms) [----------] 1 test from TwoWriteQueues/SnapshotConcurrentAccessTest (11882 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (11882 ms total) [ PASSED ] 0 tests. [ FAILED ] 1 test, listed below: [ FAILED ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1, where GetParam() = (false, true, 1, 0, 1, 20) ``` After the change: repeating the test 200 times with 200 workers didn't fail, even with repeating the "repeating" for 10 times like below `for i in {1..10}; do ~/gtest-parallel/gtest-parallel -r 200 -w 200 ./write_prepared_transaction_test --gtest_filter=TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1; done` ``` [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [200/200] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 ``` It does failed when repeating the test 400 times with 400 workers `~/project$ ~/gtest-parallel/gtest-parallel -r 400 -w 400 ./write_prepared_transaction_test --gtest_filter=TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1` ``` [1/400] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 (2928 ms) Note: Google Test filter = TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from TwoWriteQueues/SnapshotConcurrentAccessTest [ RUN ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1 unknown file: Failure C++ exception with description "std::bad_alloc" thrown in the test body. [ FAILED ] TwoWriteQueues/SnapshotConcurrentAccessTest.SnapshotConcurrentAccess/1, where GetParam() = (false, true, 1, 0, 1, 20) (2597 ms) [----------] 1 test from TwoWriteQueues/SnapshotConcurrentAccessTest (2597 ms total) ``` Reviewed By: ajkr Differential Revision: D33026776 Pulled By: hx235 fbshipit-source-id: 509f57126392821e835e48396e5bf224f4f5dcac |
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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.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/ and https://rocksdb.slack.com/
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.