91ddd587cc
Summary:
At the end of BackgroundCallCompaction(), we call SignalAll(), even though we don't need to. If compaction hasn't done anything and there's another compaction running, there is no need to signal on the condition variable. Doing so creates a tight feedback loop which results in log files like:
wait for memtable flush
compaction nothing to do
wait for memtable flush
compaction nothing to do
This change eliminates that
Test Plan:
make check
Also:
icanadi@dev1440 ~ $ grep "nothing to do" /fast-rocksdb-tmp/rocksdb_test/column_family_test/LOG | wc -l
7435
icanadi@dev1440 ~ $ grep "nothing to do" /fast-rocksdb-tmp/rocksdb_test/column_family_test/LOG | wc -l
372
First version is before the change, second version is after the change.
Reviewers: dhruba, ljin, haobo, yhchiang, sdong
Reviewed By: sdong
Subscribers: leveldb
Differential Revision: https://reviews.facebook.net/D18855
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 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 an 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 doc/index.html and 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/