92b4401566
Summary: For flush triggered by RocksDB due to memory usage approaching certain threshold (WriteBufferManager or Memtable full), we should cut the memtable only when the current active memtable is not empty, i.e. contains data. This is what we do for non-atomic flush. If we always cut memtable even when the active memtable is empty, we will generate extra, empty immutable memtable. This is not ideal since it may cause write stall. It also causes some DBAtomicFlushTest to fail because cfd->imm()->NumNotFlushed() is different from expectation. Test plan ``` $make clean && make J=1 -j32 all check $make clean && OPT="-DROCKSDB_LITE -g" make J=1 -j32 all check $make clean && TEST_TMPDIR=/dev/shm/rocksdb OPT=-g make J=1 -j32 valgrind_test ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/4595 Differential Revision: D12818520 Pulled By: riversand963 fbshipit-source-id: d867bdbeacf4199fdd642debb085f94703c41a18
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 specially suitable for storing multiple terabytes of data in a single database.
Start with example usage here: https://github.com/facebook/rocksdb/tree/master/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/
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.