diff options
| author | Simon Riggs | 2017-04-06 12:31:52 +0000 |
|---|---|---|
| committer | Simon Riggs | 2017-04-06 12:31:52 +0000 |
| commit | 6bad580d9e678a0b604883e14d8401d469b06566 (patch) | |
| tree | 44630ef43002b029704432f405ae2949081eb841 /src/backend/access | |
| parent | fd01983594b7d2119653428e3b532578008c7065 (diff) | |
Avoid SnapshotResetXmin() during AtEOXact_Snapshot()
For normal commits and aborts we already reset PgXact->xmin,
so we can simply avoid running SnapshotResetXmin() twice.
During performance tests by Alexander Korotkov, diagnosis
by Andres Freund showed PgXact array as a bottleneck. After
manual analysis by me of the code paths that touch those
memory locations, I was able to identify extraneous code
in the main transaction commit path.
Avoiding touching highly contented shmem improves concurrent
performance slightly on all workloads, confirmed by tests
run by Ashutosh Sharma and Alexander Korotkov.
Simon Riggs
Discussion: CANP8+jJdXE9b+b9F8CQT-LuxxO0PBCB-SZFfMVAdp+akqo4zfg@mail.gmail.com
Diffstat (limited to 'src/backend/access')
| -rw-r--r-- | src/backend/access/transam/xact.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 6f614e4fad0..84409ea9562 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -2137,7 +2137,7 @@ CommitTransaction(void) AtEOXact_ComboCid(); AtEOXact_HashTables(true); AtEOXact_PgStat(true); - AtEOXact_Snapshot(true); + AtEOXact_Snapshot(true, false); AtCommit_ApplyLauncher(); pgstat_report_xact_timestamp(0); @@ -2409,7 +2409,7 @@ PrepareTransaction(void) AtEOXact_ComboCid(); AtEOXact_HashTables(true); /* don't call AtEOXact_PgStat here; we fixed pgstat state above */ - AtEOXact_Snapshot(true); + AtEOXact_Snapshot(true, true); pgstat_report_xact_timestamp(0); CurrentResourceOwner = NULL; @@ -2640,7 +2640,7 @@ CleanupTransaction(void) * do abort cleanup processing */ AtCleanup_Portals(); /* now safe to release portal memory */ - AtEOXact_Snapshot(false); /* and release the transaction's snapshots */ + AtEOXact_Snapshot(false, false); /* and release the transaction's snapshots */ CurrentResourceOwner = NULL; /* and resource owner */ if (TopTransactionResourceOwner) |