Summary:
TSAN shows warning with clang with warning similar to this:
WARNING: ThreadSanitizer: data race (pid=10159)
Atomic write of size 8 at 0x7b5000002890 by thread T33:
#0 __tsan_atomic64_store <null> (db_test+0x4ca2b5)
https://github.com/facebook/rocksdb/issues/1 std::__atomic_base<unsigned long>::store(unsigned long, std::memory_order) /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.0/../../../../include/c++/5.4.0/bits/atomic_base.h:374:2 (db_test+0x774fde)
https://github.com/facebook/rocksdb/issues/2 rocksdb::VersionSet::SetLastSequence(unsigned long) /home/circleci/project/./db/version_set.h:1057:20 (db_test+0x774fde)
https://github.com/facebook/rocksdb/issues/3 rocksdb::DBImpl::WriteImpl(rocksdb::WriteOptions const&, rocksdb::WriteBatch*, rocksdb::WriteCallback*, unsigned long*, unsigned long, bool, unsigned long*, unsigned long, rocksdb::PreReleaseCallback*) /home/circleci/project/db/db_impl/db_impl_write.cc:449:18 (db_test+0x774fde)
......
Previous read of size 8 at 0x7b5000002890 by thread T5 (mutexes: write M1044689462619020832):
#0 rocksdb::DBImpl::ReleaseSnapshot(rocksdb::Snapshot const*) /home/circleci/project/db/db_impl/db_impl.cc (db_test+0x6f4ae7)
https://github.com/facebook/rocksdb/issues/1 rocksdb::(anonymous namespace)::MTThreadBody(void*) /home/circleci/project/db/db_test.cc:2514:13 (db_test+0x56ac59)
https://github.com/facebook/rocksdb/issues/2 rocksdb::(anonymous namespace)::StartThreadWrapper(void*) /home/circleci/project/env/env_posix.cc:443:3 (db_test+0x88c4cd)
It is not limited to ReleaseSnapshot() and rocksdb::DBImpl::MultiCFSnapshot().
While we are not 100% sure it doesn't indicate any correctness violation, we suppress them for now to keep TSAN clean with more tests so that we can cover more bugs with CI.
In the gcc runs we have been running, this warning rarely shows up.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7126
Test Plan: See the mini-TSAN test to pass with reasonable run time.
Reviewed By: ajkr
Differential Revision: D22552375
fbshipit-source-id: ebdd3854cb3becec3403970326a1ca961db2ab00
ca5a069a79