rocksdb/db/db_impl
Levi Tamasi 6d54eb3dc2 Do not create/install new SuperVersion if nothing was deleted during memtable trim (#6169)
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
2019-12-13 13:29:29 -08:00
..
db_impl_compaction_flush.cc Support concurrent CF iteration and drop (#6147) 2019-12-12 19:04:48 -08:00
db_impl_debug.cc Fix IngestExternalFile's bug with two_write_queue (#5976) 2019-11-15 14:00:37 -08:00
db_impl_experimental.cc Support options.max_open_files = -1 with periodic_compaction_seconds (#6090) 2019-11-26 21:39:56 -08:00
db_impl_files.cc Let DBSecondary close files after catch up (#6114) 2019-12-02 17:45:03 -08:00
db_impl_open.cc Support concurrent CF iteration and drop (#6147) 2019-12-12 19:04:48 -08:00
db_impl_readonly.cc Apply formatter on recent 45 commits. (#5827) 2019-09-19 12:34:17 -07:00
db_impl_readonly.h Use delete to disable automatic generated methods. (#5009) 2019-09-11 18:09:00 -07:00
db_impl_secondary.cc Let DBSecondary close files after catch up (#6114) 2019-12-02 17:45:03 -08:00
db_impl_secondary.h Let DBSecondary close files after catch up (#6114) 2019-12-02 17:45:03 -08:00
db_impl_write.cc Do not create/install new SuperVersion if nothing was deleted during memtable trim (#6169) 2019-12-13 13:29:29 -08:00
db_impl.cc Support concurrent CF iteration and drop (#6147) 2019-12-12 19:04:48 -08:00
db_impl.h wait pending memtable writes on file ingestion or compact range (#6113) 2019-12-12 14:08:02 -08:00
db_secondary_test.cc Break db_stress_tool.cc to a list of source files (#6134) 2019-12-08 23:51:01 -08:00