Revision 80de9004649753d87fa1b2d41127b1401a4c0065 authored by Levi Tamasi on 13 December 2019, 20:45:49 UTC, committed by Levi Tamasi on 17 December 2019, 15:52:22 UTC
Summary: We have observed an increase in CPU load caused by frequent calls to `ColumnFamilyData::InstallSuperVersion` from `DBImpl::TrimMemtableHistory` when using `max_write_buffer_size_to_maintain` to limit the amount of memtable history maintained for transaction conflict checking. As it turns out, this is caused by the code creating and installing a new `SuperVersion` even if no memtables were actually trimmed. The patch adds a check to avoid this. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6169 Test Plan: Compared `perf` output for ``` ./db_bench -benchmarks=randomtransaction -optimistic_transaction_db=1 -statistics -stats_interval_seconds=1 -duration=90 -num=500000 --max_write_buffer_size_to_maintain=16000000 --transaction_set_snapshot=1 --threads=32 ``` before and after the change. With the fix, the call chain `rocksdb::DBImpl::TrimMemtableHistory` -> `rocksdb::ColumnFamilyData::InstallSuperVersion` -> `rocksdb::ThreadLocalPtr::StaticMeta::Scrape` no longer registers in the `perf` report. Differential Revision: D19031509 Pulled By: ltamasi fbshipit-source-id: 02686fce594e5b50eba0710e4b28a9b808c8aa20
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AUTHORS
Facebook Inc.
Facebook Engineering Team
Google Inc.
# Initial version authors:
Jeffrey Dean <jeff@google.com>
Sanjay Ghemawat <sanjay@google.com>
# Partial list of contributors:
Kevin Regan <kevin.d.regan@gmail.com>
Johan Bilien <jobi@litl.com>
Matthew Von-Maszewski <https://github.com/matthewvon> (Basho Technologies)
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