database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-19 13:42:17 +03:00
Code Activity

snapshot scalability: Move PGXACT->vacuumFlags to ProcGlobal->vacuumFlags.

Browse Source 
Similar to the previous commit this increases the chance that data
frequently needed by GetSnapshotData() stays in l2 cache. As we now
take care to not unnecessarily write to ProcGlobal->vacuumFlags, there
should be very few modifications to the ProcGlobal->vacuumFlags array.

Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Reviewed-By: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/20200301083601.ews6hz5dduc3w2se@alap3.anarazel.de
This commit is contained in:
Andres Freund
2020-07-15 15:35:07 -07:00
parent 941697c3c1
commit 5788e258bb
9 changed files with 75 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

66
src/backend/storage/ipc/procarray.c
View File

@@ -476,9 +476,12 @@ ProcArrayAdd(PGPROC *proc)
(arrayP->numProcs - index) * sizeof(*arrayP->pgprocnos));
memmove(&ProcGlobal->xids[index + 1], &ProcGlobal->xids[index],
(arrayP->numProcs - index) * sizeof(*ProcGlobal->xids));
memmove(&ProcGlobal->vacuumFlags[index + 1], &ProcGlobal->vacuumFlags[index],
(arrayP->numProcs - index) * sizeof(*ProcGlobal->vacuumFlags));
arrayP->pgprocnos[index] = proc->pgprocno;
ProcGlobal->xids[index] = proc->xid;
ProcGlobal->vacuumFlags[index] = proc->vacuumFlags;
arrayP->numProcs++;
@@ -539,6 +542,7 @@ ProcArrayRemove(PGPROC *proc, TransactionId latestXid)
}
Assert(TransactionIdIsValid(ProcGlobal->xids[proc->pgxactoff] == 0));
ProcGlobal->vacuumFlags[proc->pgxactoff] = 0;
for (index = 0; index < arrayP->numProcs; index++)
{
@@ -549,6 +553,8 @@ ProcArrayRemove(PGPROC *proc, TransactionId latestXid)
(arrayP->numProcs - index - 1) * sizeof(*arrayP->pgprocnos));
memmove(&ProcGlobal->xids[index], &ProcGlobal->xids[index + 1],
(arrayP->numProcs - index - 1) * sizeof(*ProcGlobal->xids));
memmove(&ProcGlobal->vacuumFlags[index], &ProcGlobal->vacuumFlags[index + 1],
(arrayP->numProcs - index - 1) * sizeof(*ProcGlobal->vacuumFlags));
arrayP->pgprocnos[arrayP->numProcs - 1] = -1; /* for debugging */
arrayP->numProcs--;
@@ -626,14 +632,24 @@ ProcArrayEndTransaction(PGPROC *proc, TransactionId latestXid)
Assert(!TransactionIdIsValid(proc->xid));
proc->lxid = InvalidLocalTransactionId;
/* must be cleared with xid/xmin: */
pgxact->vacuumFlags &= ~PROC_VACUUM_STATE_MASK;
proc->xmin = InvalidTransactionId;
proc->delayChkpt = false; /* be sure this is cleared in abort */
proc->recoveryConflictPending = false;
Assert(pgxact->nxids == 0);
Assert(pgxact->overflowed == false);
/* must be cleared with xid/xmin: */
/* avoid unnecessarily dirtying shared cachelines */
if (proc->vacuumFlags & PROC_VACUUM_STATE_MASK)
{
Assert(!LWLockHeldByMe(ProcArrayLock));
LWLockAcquire(ProcArrayLock, LW_SHARED);
Assert(proc->vacuumFlags == ProcGlobal->vacuumFlags[proc->pgxactoff]);
proc->vacuumFlags &= ~PROC_VACUUM_STATE_MASK;
ProcGlobal->vacuumFlags[proc->pgxactoff] = proc->vacuumFlags;
LWLockRelease(ProcArrayLock);
}
}
}
@@ -654,12 +670,18 @@ ProcArrayEndTransactionInternal(PGPROC *proc, PGXACT *pgxact,
ProcGlobal->xids[pgxactoff] = InvalidTransactionId;
proc->xid = InvalidTransactionId;
proc->lxid = InvalidLocalTransactionId;
/* must be cleared with xid/xmin: */
pgxact->vacuumFlags &= ~PROC_VACUUM_STATE_MASK;
proc->xmin = InvalidTransactionId;
proc->delayChkpt = false; /* be sure this is cleared in abort */
proc->recoveryConflictPending = false;
/* must be cleared with xid/xmin: */
/* avoid unnecessarily dirtying shared cachelines */
if (proc->vacuumFlags & PROC_VACUUM_STATE_MASK)
{
proc->vacuumFlags &= ~PROC_VACUUM_STATE_MASK;
ProcGlobal->vacuumFlags[proc->pgxactoff] = proc->vacuumFlags;
}
/* Clear the subtransaction-XID cache too while holding the lock */
pgxact->nxids = 0;
pgxact->overflowed = false;
@@ -819,9 +841,8 @@ ProcArrayClearTransaction(PGPROC *proc)
proc->xmin = InvalidTransactionId;
proc->recoveryConflictPending = false;
/* redundant, but just in case */
pgxact->vacuumFlags &= ~PROC_VACUUM_STATE_MASK;
proc->delayChkpt = false;
Assert(!(proc->vacuumFlags & PROC_VACUUM_STATE_MASK));
Assert(!proc->delayChkpt);
/* Clear the subtransaction-XID cache too */
pgxact->nxids = 0;
@@ -1623,7 +1644,7 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
{
int pgprocno = arrayP->pgprocnos[index];
PGPROC *proc = &allProcs[pgprocno];
PGXACT *pgxact = &allPgXact[pgprocno];
int8 vacuumFlags = ProcGlobal->vacuumFlags[index];
TransactionId xid;
TransactionId xmin;
@@ -1640,8 +1661,8 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
*/
xmin = TransactionIdOlder(xmin, xid);
/* if neither is set, this proc doesn't influence the horizon */
if (!TransactionIdIsValid(xmin))
/* if neither is set, this proc doesn't influence the horizon */
if (!TransactionIdIsValid(xmin))
continue;
/*
@@ -1658,7 +1679,7 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
* removed, as long as pg_subtrans is not truncated) or doing logical
* decoding (which manages xmin separately, check below).
*/
if (pgxact->vacuumFlags & (PROC_IN_VACUUM | PROC_IN_LOGICAL_DECODING))
if (vacuumFlags & (PROC_IN_VACUUM | PROC_IN_LOGICAL_DECODING))
continue;
/* shared tables need to take backends in all database into account */
@@ -1998,6 +2019,7 @@ GetSnapshotData(Snapshot snapshot)
size_t numProcs = arrayP->numProcs;
TransactionId *xip = snapshot->xip;
int *pgprocnos = arrayP->pgprocnos;
uint8 *allVacuumFlags = ProcGlobal->vacuumFlags;
/*
* First collect set of pgxactoff/xids that need to be included in the
@@ -2007,8 +2029,6 @@ GetSnapshotData(Snapshot snapshot)
{
/* Fetch xid just once - see GetNewTransactionId */
TransactionId xid = UINT32_ACCESS_ONCE(other_xids[pgxactoff]);
int pgprocno;
PGXACT *pgxact;
uint8 vacuumFlags;
Assert(allProcs[arrayP->pgprocnos[pgxactoff]].pgxactoff == pgxactoff);
@@ -2044,14 +2064,11 @@ GetSnapshotData(Snapshot snapshot)
if (!NormalTransactionIdPrecedes(xid, xmax))
continue;
pgprocno = pgprocnos[pgxactoff];
pgxact = &allPgXact[pgprocno];
vacuumFlags = pgxact->vacuumFlags;
/*
* Skip over backends doing logical decoding which manages xmin
* separately (check below) and ones running LAZY VACUUM.
*/
vacuumFlags = allVacuumFlags[pgxactoff];
if (vacuumFlags & (PROC_IN_LOGICAL_DECODING | PROC_IN_VACUUM))
continue;
@@ -2078,6 +2095,9 @@ GetSnapshotData(Snapshot snapshot)
*/
if (!suboverflowed)
{
int pgprocno = pgprocnos[pgxactoff];
PGXACT *pgxact = &allPgXact[pgprocno];
if (pgxact->overflowed)
suboverflowed = true;
else
@@ -2296,11 +2316,11 @@ ProcArrayInstallImportedXmin(TransactionId xmin,
{
int pgprocno = arrayP->pgprocnos[index];
PGPROC *proc = &allProcs[pgprocno];
PGXACT *pgxact = &allPgXact[pgprocno];
int vacuumFlags = ProcGlobal->vacuumFlags[index];
TransactionId xid;
/* Ignore procs running LAZY VACUUM */
if (pgxact->vacuumFlags & PROC_IN_VACUUM)
if (vacuumFlags & PROC_IN_VACUUM)
continue;
/* We are only interested in the specific virtual transaction. */
@@ -2990,12 +3010,12 @@ GetCurrentVirtualXIDs(TransactionId limitXmin, bool excludeXmin0,
{
int pgprocno = arrayP->pgprocnos[index];
PGPROC *proc = &allProcs[pgprocno];
PGXACT *pgxact = &allPgXact[pgprocno];
uint8 vacuumFlags = ProcGlobal->vacuumFlags[index];
if (proc == MyProc)
continue;
if (excludeVacuum & pgxact->vacuumFlags)
if (excludeVacuum & vacuumFlags)
continue;
if (allDbs || proc->databaseId == MyDatabaseId)
@@ -3410,7 +3430,7 @@ CountOtherDBBackends(Oid databaseId, int *nbackends, int *nprepared)
{
int pgprocno = arrayP->pgprocnos[index];
PGPROC *proc = &allProcs[pgprocno];
PGXACT *pgxact = &allPgXact[pgprocno];
uint8 vacuumFlags = ProcGlobal->vacuumFlags[index];
if (proc->databaseId != databaseId)
continue;
@@ -3424,7 +3444,7 @@ CountOtherDBBackends(Oid databaseId, int *nbackends, int *nprepared)
else
{
(*nbackends)++;
if ((pgxact->vacuumFlags & PROC_IS_AUTOVACUUM) &&
if ((vacuumFlags & PROC_IS_AUTOVACUUM) &&
nautovacs < MAXAUTOVACPIDS)
autovac_pids[nautovacs++] = proc->pid;
}