From ae12e4be3b34ffac896d7c406f8a5f4ad5815579 Mon Sep 17 00:00:00 2001 From: Maxim Orlov Date: Tue, 10 Sep 2024 18:58:09 +0300 Subject: [PATCH v5 5/8] Remove redundant lockAwaited global variable We had two global (static) variables to hold the LOCALLOCK that we are currently acquiring: awaitedLock in lock.c and lockAwaited in proc.c. They were set at slightly different times, but when they were both set, they were the same thing. Remove the lockAwaited variable and rely on awaitedLock everywhere. --- src/backend/storage/lmgr/lock.c | 9 +++++++++ src/backend/storage/lmgr/proc.c | 30 ++++-------------------------- src/backend/tcop/postgres.c | 2 +- src/include/storage/lock.h | 2 ++ src/include/storage/proc.h | 1 - 5 files changed, 16 insertions(+), 28 deletions(-) diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c index e82a041097..4e1890276f 100644 --- a/src/backend/storage/lmgr/lock.c +++ b/src/backend/storage/lmgr/lock.c @@ -1770,6 +1770,12 @@ GrantAwaitedLock(void) GrantLockLocal(awaitedLock, awaitedOwner); } +LOCALLOCK * +GetAwaitedLock(void) +{ + return awaitedLock; +} + /* * MarkLockClear -- mark an acquired lock as "clear" * @@ -1866,6 +1872,9 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner, bool dontWait) } PG_END_TRY(); + /* + * We no longer want LockErrorCleanup to do anything. + */ awaitedLock = NULL; /* reset ps display to remove the suffix */ diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 9aff57a519..e8084dd3d5 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -80,9 +80,6 @@ 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; - static DeadLockState deadlock_state = DS_NOT_YET_CHECKED; /* Is a deadlock check pending? */ @@ -707,18 +704,6 @@ HaveNFreeProcs(int n, int *nfree) return (*nfree == n); } -/* - * Check if the current process is awaiting a lock. - */ -bool -IsWaitingForLock(void) -{ - if (lockAwaited == NULL) - return false; - - return true; -} - /* * Cancel any pending wait for lock, when aborting a transaction, and revert * any strong lock count acquisition for a lock being acquired. @@ -730,6 +715,7 @@ IsWaitingForLock(void) void LockErrorCleanup(void) { + LOCALLOCK *lockAwaited; LWLock *partitionLock; DisableTimeoutParams timeouts[2]; @@ -738,6 +724,7 @@ LockErrorCleanup(void) AbortStrongLockAcquire(); /* Nothing to do if we weren't waiting for a lock */ + lockAwaited = GetAwaitedLock(); if (lockAwaited == NULL) { RESUME_INTERRUPTS(); @@ -1218,9 +1205,6 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait) return PROC_WAIT_STATUS_ERROR; } - /* mark that we are waiting for a lock */ - lockAwaited = locallock; - /* * Release the lock table's partition lock. * @@ -1645,17 +1629,11 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait) NULL, false); /* - * Re-acquire the lock table's partition lock. We have to do this to hold - * off cancel/die interrupts before we can mess with lockAwaited (else we - * might have a missed or duplicated locallock update). + * Re-acquire the lock table's partition lock, because the caller expects + * us to still hold it. */ LWLockAcquire(partitionLock, LW_EXCLUSIVE); - /* - * We no longer want LockErrorCleanup to do anything. - */ - lockAwaited = NULL; - /* * If we got the lock, be sure to remember it in the locallock table. */ diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 8bc6bea113..9b800b72bf 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -3062,7 +3062,7 @@ ProcessRecoveryConflictInterrupt(ProcSignalReason reason) /* * If we aren't waiting for a lock we can never deadlock. */ - if (!IsWaitingForLock()) + if (GetAwaitedLock() == NULL) return; /* Intentional fall through to check wait for pin */ diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h index 8b328a06d9..787f3db06a 100644 --- a/src/include/storage/lock.h +++ b/src/include/storage/lock.h @@ -585,6 +585,8 @@ extern bool LockCheckConflicts(LockMethod lockMethodTable, LOCK *lock, PROCLOCK *proclock); extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode); extern void GrantAwaitedLock(void); +extern LOCALLOCK *GetAwaitedLock(void); + extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode); extern LockData *GetLockStatusData(void); extern BlockedProcsData *GetBlockerStatusData(int blocked_pid); diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index deeb06c9e0..7ddfc8f392 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -481,7 +481,6 @@ extern ProcWaitStatus ProcSleep(LOCALLOCK *locallock, extern void ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus); extern void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock); extern void CheckDeadLockAlert(void); -extern bool IsWaitingForLock(void); extern void LockErrorCleanup(void); extern void ProcWaitForSignal(uint32 wait_event_info); -- 2.34.1