andreacavalli/rocksdb
0
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Avoid switching empty memtable in certain cases (#4792)

Browse Source 
Summary:
in certain cases, we do not perform memtable switching if the active
memtable of the column family is empty. Two exceptions:
1. In manual flush, if cached_recoverable_state_empty_ is false, then we need
   to switch memtable due to requirement of transaction.
2. In switch WAL, we need to switch memtable anyway because we have to seal the
   memtable if the WAL on which it depends will be closed.

This change can potentially delay the occurence of write stalls because number
of memtables increase more slowly.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4792

Differential Revision: D13499501

Pulled By: riversand963

fbshipit-source-id: 91c9b17ae753578578039f3851667d93610005e1
This commit is contained in:
Yanqin Jin 2018-12-18 16:43:12 -08:00
parent 663d24f467
commit e265e08a02
1 changed files with 12 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
db/db_impl_compaction_flush.cc
View File

@ -1462,11 +1462,16 @@ Status DBImpl::FlushMemTable(ColumnFamilyData* cfd,
write_thread_.EnterUnbatched(&w, &mutex_);
}
if (cfd->imm()->NumNotFlushed() != 0 || !cfd->mem()->IsEmpty() ||
!cached_recoverable_state_empty_.load()) {
if (!cfd->mem()->IsEmpty() || !cached_recoverable_state_empty_.load()) {
s = SwitchMemtable(cfd, &context);
flush_memtable_id = cfd->imm()->GetLatestMemTableID();
flush_req.emplace_back(cfd, flush_memtable_id);
}
if (s.ok()) {
if (cfd->imm()->NumNotFlushed() != 0 || !cfd->mem()->IsEmpty() ||
!cached_recoverable_state_empty_.load()) {
flush_memtable_id = cfd->imm()->GetLatestMemTableID();
flush_req.emplace_back(cfd, flush_memtable_id);
}
}
if (s.ok() && !flush_req.empty()) {
@ -1540,6 +1545,9 @@ Status DBImpl::AtomicFlushMemTables(
}
}
for (auto cfd : cfds) {
if (cfd->mem()->IsEmpty() && cached_recoverable_state_empty_.load()) {
continue;
}
cfd->Ref();
s = SwitchMemtable(cfd, &context);
cfd->Unref();