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Diffstat (limited to 'src/backend/storage/lmgr/proc.c')
-rw-r--r--src/backend/storage/lmgr/proc.c87
1 files changed, 62 insertions, 25 deletions
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index eda3a98a85b..bcbc80222bb 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -36,6 +36,7 @@
#include <sys/time.h>
#include "access/transam.h"
+#include "access/twophase.h"
#include "access/xact.h"
#include "miscadmin.h"
#include "postmaster/autovacuum.h"
@@ -57,6 +58,7 @@ bool log_lock_waits = false;
/* Pointer to this process's PGPROC struct, if any */
PGPROC *MyProc = NULL;
+PGXACT *MyPgXact = NULL;
/*
* This spinlock protects the freelist of recycled PGPROC structures.
@@ -70,6 +72,7 @@ NON_EXEC_STATIC slock_t *ProcStructLock = NULL;
/* Pointers to shared-memory structures */
PROC_HDR *ProcGlobal = NULL;
NON_EXEC_STATIC PGPROC *AuxiliaryProcs = NULL;
+PGPROC *PreparedXactProcs = NULL;
/* If we are waiting for a lock, this points to the associated LOCALLOCK */
static LOCALLOCK *lockAwaited = NULL;
@@ -106,13 +109,19 @@ ProcGlobalShmemSize(void)
/* ProcGlobal */
size = add_size(size, sizeof(PROC_HDR));
- /* AuxiliaryProcs */
- size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGPROC)));
/* MyProcs, including autovacuum workers and launcher */
size = add_size(size, mul_size(MaxBackends, sizeof(PGPROC)));
+ /* AuxiliaryProcs */
+ size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGPROC)));
+ /* Prepared xacts */
+ size = add_size(size, mul_size(max_prepared_xacts, sizeof(PGPROC)));
/* ProcStructLock */
size = add_size(size, sizeof(slock_t));
+ size = add_size(size, mul_size(MaxBackends, sizeof(PGXACT)));
+ size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGXACT)));
+ size = add_size(size, mul_size(max_prepared_xacts, sizeof(PGXACT)));
+
return size;
}
@@ -157,10 +166,11 @@ void
InitProcGlobal(void)
{
PGPROC *procs;
+ PGXACT *pgxacts;
int i,
j;
bool found;
- uint32 TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS;
+ uint32 TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts;
/* Create the ProcGlobal shared structure */
ProcGlobal = (PROC_HDR *)
@@ -182,10 +192,11 @@ InitProcGlobal(void)
* those used for 2PC, which are embedded within a GlobalTransactionData
* struct).
*
- * There are three separate consumers of PGPROC structures: (1) normal
- * backends, (2) autovacuum workers and the autovacuum launcher, and (3)
- * auxiliary processes. Each PGPROC structure is dedicated to exactly
- * one of these purposes, and they do not move between groups.
+ * There are four separate consumers of PGPROC structures: (1) normal
+ * backends, (2) autovacuum workers and the autovacuum launcher, (3)
+ * auxiliary processes, and (4) prepared transactions. Each PGPROC
+ * structure is dedicated to exactly one of these purposes, and they do
+ * not move between groups.
*/
procs = (PGPROC *) ShmemAlloc(TotalProcs * sizeof(PGPROC));
ProcGlobal->allProcs = procs;
@@ -195,21 +206,43 @@ InitProcGlobal(void)
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory")));
MemSet(procs, 0, TotalProcs * sizeof(PGPROC));
+
+ /*
+ * Also allocate a separate array of PGXACT structures. This is separate
+ * from the main PGPROC array so that the most heavily accessed data is
+ * stored contiguously in memory in as few cache lines as possible. This
+ * provides significant performance benefits, especially on a
+ * multiprocessor system. Thereis one PGXACT structure for every PGPROC
+ * structure.
+ */
+ pgxacts = (PGXACT *) ShmemAlloc(TotalProcs * sizeof(PGXACT));
+ MemSet(pgxacts, 0, TotalProcs * sizeof(PGXACT));
+ ProcGlobal->allPgXact = pgxacts;
+
for (i = 0; i < TotalProcs; i++)
{
/* Common initialization for all PGPROCs, regardless of type. */
- /* Set up per-PGPROC semaphore, latch, and backendLock */
- PGSemaphoreCreate(&(procs[i].sem));
- InitSharedLatch(&(procs[i].procLatch));
- procs[i].backendLock = LWLockAssign();
+ /*
+ * Set up per-PGPROC semaphore, latch, and backendLock. Prepared
+ * xact dummy PGPROCs don't need these though - they're never
+ * associated with a real process
+ */
+ if (i < MaxBackends + NUM_AUXILIARY_PROCS)
+ {
+ PGSemaphoreCreate(&(procs[i].sem));
+ InitSharedLatch(&(procs[i].procLatch));
+ procs[i].backendLock = LWLockAssign();
+ }
+ procs[i].pgprocno = i;
/*
* Newly created PGPROCs for normal backends or for autovacuum must
* be queued up on the appropriate free list. Because there can only
* ever be a small, fixed number of auxiliary processes, no free
* list is used in that case; InitAuxiliaryProcess() instead uses a
- * linear search.
+ * linear search. PGPROCs for prepared transactions are added to a
+ * free list by TwoPhaseShmemInit().
*/
if (i < MaxConnections)
{
@@ -230,10 +263,11 @@ InitProcGlobal(void)
}
/*
- * Save a pointer to the block of PGPROC structures reserved for
- * auxiliary proceses.
+ * Save pointers to the blocks of PGPROC structures reserved for
+ * auxiliary processes and prepared transactions.
*/
AuxiliaryProcs = &procs[MaxBackends];
+ PreparedXactProcs = &procs[MaxBackends + NUM_AUXILIARY_PROCS];
/* Create ProcStructLock spinlock, too */
ProcStructLock = (slock_t *) ShmemAlloc(sizeof(slock_t));
@@ -296,6 +330,7 @@ InitProcess(void)
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("sorry, too many clients already")));
}
+ MyPgXact = &ProcGlobal->allPgXact[MyProc->pgprocno];
/*
* Now that we have a PGPROC, mark ourselves as an active postmaster
@@ -313,18 +348,18 @@ InitProcess(void)
SHMQueueElemInit(&(MyProc->links));
MyProc->waitStatus = STATUS_OK;
MyProc->lxid = InvalidLocalTransactionId;
- MyProc->xid = InvalidTransactionId;
- MyProc->xmin = InvalidTransactionId;
+ MyPgXact->xid = InvalidTransactionId;
+ MyPgXact->xmin = InvalidTransactionId;
MyProc->pid = MyProcPid;
/* backendId, databaseId and roleId will be filled in later */
MyProc->backendId = InvalidBackendId;
MyProc->databaseId = InvalidOid;
MyProc->roleId = InvalidOid;
- MyProc->inCommit = false;
- MyProc->vacuumFlags = 0;
+ MyPgXact->inCommit = false;
+ MyPgXact->vacuumFlags = 0;
/* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
if (IsAutoVacuumWorkerProcess())
- MyProc->vacuumFlags |= PROC_IS_AUTOVACUUM;
+ MyPgXact->vacuumFlags |= PROC_IS_AUTOVACUUM;
MyProc->lwWaiting = false;
MyProc->lwExclusive = false;
MyProc->lwWaitLink = NULL;
@@ -462,6 +497,7 @@ InitAuxiliaryProcess(void)
((volatile PGPROC *) auxproc)->pid = MyProcPid;
MyProc = auxproc;
+ MyPgXact = &ProcGlobal->allPgXact[auxproc->pgprocno];
SpinLockRelease(ProcStructLock);
@@ -472,13 +508,13 @@ InitAuxiliaryProcess(void)
SHMQueueElemInit(&(MyProc->links));
MyProc->waitStatus = STATUS_OK;
MyProc->lxid = InvalidLocalTransactionId;
- MyProc->xid = InvalidTransactionId;
- MyProc->xmin = InvalidTransactionId;
+ MyPgXact->xid = InvalidTransactionId;
+ MyPgXact->xmin = InvalidTransactionId;
MyProc->backendId = InvalidBackendId;
MyProc->databaseId = InvalidOid;
MyProc->roleId = InvalidOid;
- MyProc->inCommit = false;
- MyProc->vacuumFlags = 0;
+ MyPgXact->inCommit = false;
+ MyPgXact->vacuumFlags = 0;
MyProc->lwWaiting = false;
MyProc->lwExclusive = false;
MyProc->lwWaitLink = NULL;
@@ -1045,6 +1081,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM && allow_autovacuum_cancel)
{
PGPROC *autovac = GetBlockingAutoVacuumPgproc();
+ PGXACT *autovac_pgxact = &ProcGlobal->allPgXact[autovac->pgprocno];
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
@@ -1053,8 +1090,8 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
* wraparound.
*/
if ((autovac != NULL) &&
- (autovac->vacuumFlags & PROC_IS_AUTOVACUUM) &&
- !(autovac->vacuumFlags & PROC_VACUUM_FOR_WRAPAROUND))
+ (autovac_pgxact->vacuumFlags & PROC_IS_AUTOVACUUM) &&
+ !(autovac_pgxact->vacuumFlags & PROC_VACUUM_FOR_WRAPAROUND))
{
int pid = autovac->pid;
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-28 14:33:29 +0000