e85f2c64cb
Summary: This fixes OOMs that we (logdevice) are currently having in production. SkipListRep constructor does a couple small allocations from ConcurrentArena (see InlineSkipList constructor). ConcurrentArena would sometimes allocate an entire block for that, which is a few megabytes (we use Options::arena_block_size = 4 MB). So an empty memtable can take take 4 MB of memory. We have ~40k column families (spread across 15 DB instances), so 4 MB per empty memtable easily OOMs a machine for us. This PR makes ConcurrentArena always allocate from Arena's inline block when possible. So as long as InlineSkipList's initial allocations are below 2 KB there would be no blocks allocated for empty memtables. Closes https://github.com/facebook/rocksdb/pull/2569 Differential Revision: D5404029 Pulled By: al13n321 fbshipit-source-id: 568ec22a3fd1a485c06123f6b2dfc5e9ef67cd23
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/