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Move "hot" members of PGPROC into a separate PGXACT array.

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This speeds up snapshot-taking and reduces ProcArrayLock contention.
Also, the PGPROC (and PGXACT) structures used by two-phase commit are
now allocated as part of the main array, rather than in a separate
array, and we keep ProcArray sorted in pointer order.  These changes
are intended to minimize the number of cache lines that must be pulled
in to take a snapshot, and testing shows a substantial increase in
performance on both read and write workloads at high concurrencies.

Pavan Deolasee, Heikki Linnakangas, Robert Haas
This commit is contained in:
Robert Haas
2011-11-25 08:02:10 -05:00
parent 9ed439a9c0
commit ed0b409d22
14 changed files with 356 additions and 208 deletions
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4
src/backend/storage/lmgr/deadlock.c
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@@ -450,6 +450,7 @@ FindLockCycleRecurse(PGPROC *checkProc,
int *nSoftEdges) /* output argument */
{
PGPROC *proc;
PGXACT *pgxact;
LOCK *lock;
PROCLOCK *proclock;
SHM_QUEUE *procLocks;
@@ -516,6 +517,7 @@ FindLockCycleRecurse(PGPROC *checkProc,
while (proclock)
{
proc = proclock->tag.myProc;
pgxact = &ProcGlobal->allPgXact[proc->pgprocno];
/* A proc never blocks itself */
if (proc != checkProc)
@@ -541,7 +543,7 @@ FindLockCycleRecurse(PGPROC *checkProc,
* vacuumFlag bit), but we don't do that here to avoid
* grabbing ProcArrayLock.
*/
if (proc->vacuumFlags & PROC_IS_AUTOVACUUM)
if (pgxact->vacuumFlags & PROC_IS_AUTOVACUUM)
blocking_autovacuum_proc = proc;
/* This proc hard-blocks checkProc */