diff options
Diffstat (limited to 'src/backend/storage/lmgr/proc.c')
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 67 |
1 files changed, 37 insertions, 30 deletions
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index deca35c8d42..893ea41833d 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.28 1998/01/25 05:14:09 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.29 1998/01/27 03:00:29 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -46,7 +46,7 @@ * This is so that we can support more backends. (system-wide semaphore * sets run out pretty fast.) -ay 4/95 * - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.28 1998/01/25 05:14:09 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.29 1998/01/27 03:00:29 momjian Exp $ */ #include <sys/time.h> #include <unistd.h> @@ -442,7 +442,7 @@ ProcQueueInit(PROC_QUEUE *queue) * NOTES: The process queue is now a priority queue for locking. */ int -ProcSleep(PROC_QUEUE *queue, +ProcSleep(PROC_QUEUE *waitQueue, SPINLOCK spinlock, int token, int prio, @@ -453,8 +453,8 @@ ProcSleep(PROC_QUEUE *queue, struct itimerval timeval, dummy; - proc = (PROC *) MAKE_PTR(queue->links.prev); - for (i = 0; i < queue->size; i++) + proc = (PROC *) MAKE_PTR(waitQueue->links.prev); + for (i = 0; i < waitQueue->size; i++) { if (proc->prio >= prio) proc = (PROC *) MAKE_PTR(proc->links.prev); @@ -478,36 +478,38 @@ ProcSleep(PROC_QUEUE *queue, * ------------------- */ SHMQueueInsertTL(&(proc->links), &(MyProc->links)); - queue->size++; + waitQueue->size++; SpinRelease(spinlock); /* -------------- - * Postgres does not have any deadlock detection code and for this - * reason we must set a timer to wake up the process in the event of - * a deadlock. For now the timer is set for 1 minute and we assume that - * any process which sleeps for this amount of time is deadlocked and will - * receive a SIGALRM signal. The handler should release the processes - * semaphore and abort the current transaction. + * We set this so we can wake up periodically and check for a deadlock. + * If a deadlock is detected, the handler releases the processes + * semaphore and aborts the current transaction. * * Need to zero out struct to set the interval and the micro seconds fields * to 0. * -------------- */ MemSet(&timeval, 0, sizeof(struct itimerval)); - timeval.it_value.tv_sec = DEADLOCK_TIMEOUT; + timeval.it_value.tv_sec = DEADLOCK_CHECK_TIMER; - if (setitimer(ITIMER_REAL, &timeval, &dummy)) - elog(FATAL, "ProcSleep: Unable to set timer for process wakeup"); + do + { + MyProc->errType = NO_ERROR; /* reset flag after deadlock check */ - /* -------------- - * if someone wakes us between SpinRelease and IpcSemaphoreLock, - * IpcSemaphoreLock will not block. The wakeup is "saved" by - * the semaphore implementation. - * -------------- - */ - IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, IpcExclusiveLock); + if (setitimer(ITIMER_REAL, &timeval, &dummy)) + elog(FATAL, "ProcSleep: Unable to set timer for process wakeup"); + /* -------------- + * if someone wakes us between SpinRelease and IpcSemaphoreLock, + * IpcSemaphoreLock will not block. The wakeup is "saved" by + * the semaphore implementation. + * -------------- + */ + IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, IpcExclusiveLock); + } while (MyProc->errType == STATUS_NOT_FOUND); /* sleep after deadlock check */ + /* --------------- * We were awoken before a timeout - now disable the timer * --------------- @@ -615,10 +617,9 @@ ProcAddLock(SHM_QUEUE *elem) } /* -------------------- - * We only get to this routine if we got SIGALRM after DEADLOCK_TIMEOUT - * while waiting for a lock to be released by some other process. After - * the one minute deadline we assume we have a deadlock and must abort - * this transaction. We must also indicate that I'm no longer waiting + * We only get to this routine if we got SIGALRM after DEADLOCK_CHECK_TIMER + * while waiting for a lock to be released by some other process. If we have + * a real deadlock, we must also indicate that I'm no longer waiting * on a lock so that other processes don't try to wake me up and screw * up my semaphore. * -------------------- @@ -665,12 +666,19 @@ HandleDeadLock(int sig) return; } - mywaitlock = MyProc->waitLock; - #ifdef DEADLOCK_DEBUG DumpLocks(); #endif + if (!DeadLockCheck(&(MyProc->lockQueue), MyProc->waitLock, true)) + { + UnlockLockTable(); + MyProc->errType = STATUS_NOT_FOUND; + return; + } + + mywaitlock = MyProc->waitLock; + /* ------------------------ * Get this process off the lock's wait queue * ------------------------ @@ -701,8 +709,7 @@ HandleDeadLock(int sig) */ UnlockLockTable(); - elog(NOTICE, "Timeout interval reached -- possible deadlock."); - elog(NOTICE, "See the lock(l) manual page for a possible cause."); + elog(NOTICE, "Deadlock detected -- See the lock(l) manual page for a possible cause."); return; } |