示例#1
0
/*
 * ProcKill() -- Destroy the per-proc data structure for
 *		this process. Release any of its held LW locks.
 */
static void
ProcKill(int code, Datum arg)
{
	/* use volatile pointer to prevent code rearrangement */
	volatile PROC_HDR *procglobal = ProcGlobal;
	PGPROC	   *proc;

	Assert(MyProc != NULL);

	/* Make sure we're out of the sync rep lists */
	SyncRepCleanupAtProcExit();

#ifdef USE_ASSERT_CHECKING
	{
		int			i;

		/* Last process should have released all locks. */
		for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
			Assert(SHMQueueEmpty(&(MyProc->myProcLocks[i])));
	}
#endif

	/*
	 * Release any LW locks I am holding.  There really shouldn't be any, but
	 * it's cheap to check again before we cut the knees off the LWLock
	 * facility by releasing our PGPROC ...
	 */
	LWLockReleaseAll();

	/* Make sure active replication slots are released */
	if (MyReplicationSlot != NULL)
		ReplicationSlotRelease();

	/*
	 * Reset MyLatch to the process local one.  This is so that signal
	 * handlers et al can continue using the latch after the shared latch
	 * isn't ours anymore. After that clear MyProc and disown the shared
	 * latch.
	 */
	SwitchBackToLocalLatch();
	proc = MyProc;
	MyProc = NULL;
	DisownLatch(&proc->procLatch);

	SpinLockAcquire(ProcStructLock);

	/* Return PGPROC structure (and semaphore) to appropriate freelist */
	if (IsAnyAutoVacuumProcess())
	{
		proc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs;
		procglobal->autovacFreeProcs = proc;
	}
	else if (IsBackgroundWorker)
	{
		proc->links.next = (SHM_QUEUE *) procglobal->bgworkerFreeProcs;
		procglobal->bgworkerFreeProcs = proc;
	}
	else
	{
		proc->links.next = (SHM_QUEUE *) procglobal->freeProcs;
		procglobal->freeProcs = proc;
	}

	/* Update shared estimate of spins_per_delay */
	procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay);

	SpinLockRelease(ProcStructLock);

	/*
	 * This process is no longer present in shared memory in any meaningful
	 * way, so tell the postmaster we've cleaned up acceptably well. (XXX
	 * autovac launcher should be included here someday)
	 */
	if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
		MarkPostmasterChildInactive();

	/* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
	if (AutovacuumLauncherPid != 0)
		kill(AutovacuumLauncherPid, SIGUSR2);
}
示例#2
0
/*
 * InitProcess -- initialize a per-process data structure for this backend
 */
void
InitProcess(void)
{
	/* use volatile pointer to prevent code rearrangement */
	volatile PROC_HDR *procglobal = ProcGlobal;

	/*
	 * ProcGlobal should be set up already (if we are a backend, we inherit
	 * this by fork() or EXEC_BACKEND mechanism from the postmaster).
	 */
	if (procglobal == NULL)
		elog(PANIC, "proc header uninitialized");

	if (MyProc != NULL)
		elog(ERROR, "you already exist");

	/*
	 * Try to get a proc struct from the free list.  If this fails, we must be
	 * out of PGPROC structures (not to mention semaphores).
	 *
	 * While we are holding the ProcStructLock, also copy the current shared
	 * estimate of spins_per_delay to local storage.
	 */
	SpinLockAcquire(ProcStructLock);

	set_spins_per_delay(procglobal->spins_per_delay);

	if (IsAnyAutoVacuumProcess())
		MyProc = procglobal->autovacFreeProcs;
	else if (IsBackgroundWorker)
		MyProc = procglobal->bgworkerFreeProcs;
	else
		MyProc = procglobal->freeProcs;

	if (MyProc != NULL)
	{
		if (IsAnyAutoVacuumProcess())
			procglobal->autovacFreeProcs = (PGPROC *) MyProc->links.next;
		else if (IsBackgroundWorker)
			procglobal->bgworkerFreeProcs = (PGPROC *) MyProc->links.next;
		else
			procglobal->freeProcs = (PGPROC *) MyProc->links.next;
		SpinLockRelease(ProcStructLock);
	}
	else
	{
		/*
		 * If we reach here, all the PGPROCs are in use.  This is one of the
		 * possible places to detect "too many backends", so give the standard
		 * error message.  XXX do we need to give a different failure message
		 * in the autovacuum case?
		 */
		SpinLockRelease(ProcStructLock);
		ereport(FATAL,
				(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
	 * child; this is so that the postmaster can detect it if we exit without
	 * cleaning up.  (XXX autovac launcher currently doesn't participate in
	 * this; it probably should.)
	 */
	if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
		MarkPostmasterChildActive();

	/*
	 * Initialize all fields of MyProc, except for those previously
	 * initialized by InitProcGlobal.
	 */
	SHMQueueElemInit(&(MyProc->links));
	MyProc->waitStatus = STATUS_OK;
	MyProc->lxid = InvalidLocalTransactionId;
	MyProc->fpVXIDLock = false;
	MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
	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;
	MyPgXact->delayChkpt = false;
	MyPgXact->vacuumFlags = 0;
	/* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
	if (IsAutoVacuumWorkerProcess())
		MyPgXact->vacuumFlags |= PROC_IS_AUTOVACUUM;
	MyProc->lwWaiting = false;
	MyProc->lwWaitMode = 0;
	MyProc->waitLock = NULL;
	MyProc->waitProcLock = NULL;
#ifdef USE_ASSERT_CHECKING
	{
		int			i;

		/* Last process should have released all locks. */
		for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
			Assert(SHMQueueEmpty(&(MyProc->myProcLocks[i])));
	}
#endif
	MyProc->recoveryConflictPending = false;

	/* Initialize fields for sync rep */
	MyProc->waitLSN = 0;
	MyProc->syncRepState = SYNC_REP_NOT_WAITING;
	SHMQueueElemInit(&(MyProc->syncRepLinks));

	/*
	 * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
	 * on it.  That allows us to repoint the process latch, which so far
	 * points to process local one, to the shared one.
	 */
	OwnLatch(&MyProc->procLatch);
	SwitchToSharedLatch();

	/*
	 * We might be reusing a semaphore that belonged to a failed process. So
	 * be careful and reinitialize its value here.  (This is not strictly
	 * necessary anymore, but seems like a good idea for cleanliness.)
	 */
	PGSemaphoreReset(&MyProc->sem);

	/*
	 * Arrange to clean up at backend exit.
	 */
	on_shmem_exit(ProcKill, 0);

	/*
	 * Now that we have a PGPROC, we could try to acquire locks, so initialize
	 * local state needed for LWLocks, and the deadlock checker.
	 */
	InitLWLockAccess();
	InitDeadLockChecking();
}
示例#3
0
/*
 * InitAuxiliaryProcess -- create a per-auxiliary-process data structure
 *
 * This is called by bgwriter and similar processes so that they will have a
 * MyProc value that's real enough to let them wait for LWLocks.  The PGPROC
 * and sema that are assigned are one of the extra ones created during
 * InitProcGlobal.
 *
 * Auxiliary processes are presently not expected to wait for real (lockmgr)
 * locks, so we need not set up the deadlock checker.  They are never added
 * to the ProcArray or the sinval messaging mechanism, either.  They also
 * don't get a VXID assigned, since this is only useful when we actually
 * hold lockmgr locks.
 *
 * Startup process however uses locks but never waits for them in the
 * normal backend sense. Startup process also takes part in sinval messaging
 * as a sendOnly process, so never reads messages from sinval queue. So
 * Startup process does have a VXID and does show up in pg_locks.
 */
void
InitAuxiliaryProcess(void)
{
	PGPROC	   *auxproc;
	int			proctype;

	/*
	 * ProcGlobal should be set up already (if we are a backend, we inherit
	 * this by fork() or EXEC_BACKEND mechanism from the postmaster).
	 */
	if (ProcGlobal == NULL || AuxiliaryProcs == NULL)
		elog(PANIC, "proc header uninitialized");

	if (MyProc != NULL)
		elog(ERROR, "you already exist");

	/*
	 * We use the ProcStructLock to protect assignment and releasing of
	 * AuxiliaryProcs entries.
	 *
	 * While we are holding the ProcStructLock, also copy the current shared
	 * estimate of spins_per_delay to local storage.
	 */
	SpinLockAcquire(ProcStructLock);

	set_spins_per_delay(ProcGlobal->spins_per_delay);

	/*
	 * Find a free auxproc ... *big* trouble if there isn't one ...
	 */
	for (proctype = 0; proctype < NUM_AUXILIARY_PROCS; proctype++)
	{
		auxproc = &AuxiliaryProcs[proctype];
		if (auxproc->pid == 0)
			break;
	}
	if (proctype >= NUM_AUXILIARY_PROCS)
	{
		SpinLockRelease(ProcStructLock);
		elog(FATAL, "all AuxiliaryProcs are in use");
	}

	/* Mark auxiliary proc as in use by me */
	/* use volatile pointer to prevent code rearrangement */
	((volatile PGPROC *) auxproc)->pid = MyProcPid;

	MyProc = auxproc;
	MyPgXact = &ProcGlobal->allPgXact[auxproc->pgprocno];

	SpinLockRelease(ProcStructLock);

	/*
	 * Initialize all fields of MyProc, except for those previously
	 * initialized by InitProcGlobal.
	 */
	SHMQueueElemInit(&(MyProc->links));
	MyProc->waitStatus = STATUS_OK;
	MyProc->lxid = InvalidLocalTransactionId;
	MyProc->fpVXIDLock = false;
	MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
	MyPgXact->xid = InvalidTransactionId;
	MyPgXact->xmin = InvalidTransactionId;
	MyProc->backendId = InvalidBackendId;
	MyProc->databaseId = InvalidOid;
	MyProc->roleId = InvalidOid;
	MyPgXact->delayChkpt = false;
	MyPgXact->vacuumFlags = 0;
	MyProc->lwWaiting = false;
	MyProc->lwWaitMode = 0;
	MyProc->waitLock = NULL;
	MyProc->waitProcLock = NULL;
#ifdef USE_ASSERT_CHECKING
	{
		int			i;

		/* Last process should have released all locks. */
		for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
			Assert(SHMQueueEmpty(&(MyProc->myProcLocks[i])));
	}
#endif

	/*
	 * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
	 * on it.  That allows us to repoint the process latch, which so far
	 * points to process local one, to the shared one.
	 */
	OwnLatch(&MyProc->procLatch);
	SwitchToSharedLatch();

	/*
	 * We might be reusing a semaphore that belonged to a failed process. So
	 * be careful and reinitialize its value here.  (This is not strictly
	 * necessary anymore, but seems like a good idea for cleanliness.)
	 */
	PGSemaphoreReset(&MyProc->sem);

	/*
	 * Arrange to clean up at process exit.
	 */
	on_shmem_exit(AuxiliaryProcKill, Int32GetDatum(proctype));
}
示例#4
0
/*
 * ProcKill() -- Destroy the per-proc data structure for
 *		this process. Release any of its held LW locks.
 */
static void
ProcKill(int code, Datum arg)
{
	/* use volatile pointer to prevent code rearrangement */
	volatile PROC_HDR *procglobal = ProcGlobal;

	Assert(MyProc != NULL);

	/* Make sure we're out of the sync rep lists */
	SyncRepCleanupAtProcExit();

#ifdef USE_ASSERT_CHECKING
	if (assert_enabled)
	{
		int			i;

		/* Last process should have released all locks. */
		for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
			Assert(SHMQueueEmpty(&(MyProc->myProcLocks[i])));
	}
#endif

	/*
	 * Release any LW locks I am holding.  There really shouldn't be any, but
	 * it's cheap to check again before we cut the knees off the LWLock
	 * facility by releasing our PGPROC ...
	 */
	LWLockReleaseAll();

	/* Release ownership of the process's latch, too */
	DisownLatch(&MyProc->procLatch);

	SpinLockAcquire(ProcStructLock);

	/* Return PGPROC structure (and semaphore) to appropriate freelist */
	if (IsAnyAutoVacuumProcess())
	{
		MyProc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs;
		procglobal->autovacFreeProcs = MyProc;
	}
	else
	{
		MyProc->links.next = (SHM_QUEUE *) procglobal->freeProcs;
		procglobal->freeProcs = MyProc;
	}

	/* PGPROC struct isn't mine anymore */
	MyProc = NULL;

	/* Update shared estimate of spins_per_delay */
	procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay);

	SpinLockRelease(ProcStructLock);

	/*
	 * This process is no longer present in shared memory in any meaningful
	 * way, so tell the postmaster we've cleaned up acceptably well. (XXX
	 * autovac launcher should be included here someday)
	 */
	if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
		MarkPostmasterChildInactive();

	/* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
	if (AutovacuumLauncherPid != 0)
		kill(AutovacuumLauncherPid, SIGUSR2);
}