Esempio n. 1
0
/* Allocate and initialize walsender-related shared memory */
void
WalSndShmemInit(void)
{
	bool		found;
	int			i;

	WalSndCtl = (WalSndCtlData *)
		ShmemInitStruct("Wal Sender Ctl", WalSndShmemSize(), &found);

	if (!found)
	{
		/* First time through, so initialize */
		MemSet(WalSndCtl, 0, WalSndShmemSize());

		SHMQueueInit(&(WalSndCtl->SyncRepQueue));

		for (i = 0; i < max_wal_senders; i++)
		{
			WalSnd	   *walsnd = &WalSndCtl->walsnds[i];

			SpinLockInit(&walsnd->mutex);
			InitSharedLatch(&walsnd->latch);
		}
	}
}
Esempio n. 2
0
/* Allocate and initialize walreceiver-related shared memory */
void
WalRcvShmemInit(void)
{
	bool		found;

	WalRcv = (WalRcvData *)
		ShmemInitStruct("Wal Receiver Ctl", WalRcvShmemSize(), &found);

	if (!found)
	{
		/* First time through, so initialize */
		MemSet(WalRcv, 0, WalRcvShmemSize());
		WalRcv->walRcvState = WALRCV_STOPPED;
		SpinLockInit(&WalRcv->mutex);
		InitSharedLatch(&WalRcv->latch);
	}
}
Esempio n. 3
0
/*
 * InitProcGlobal -
 *	  Initialize the global process table during postmaster or standalone
 *	  backend startup.
 *
 *	  We also create all the per-process semaphores we will need to support
 *	  the requested number of backends.  We used to allocate semaphores
 *	  only when backends were actually started up, but that is bad because
 *	  it lets Postgres fail under load --- a lot of Unix systems are
 *	  (mis)configured with small limits on the number of semaphores, and
 *	  running out when trying to start another backend is a common failure.
 *	  So, now we grab enough semaphores to support the desired max number
 *	  of backends immediately at initialization --- if the sysadmin has set
 *	  MaxConnections, max_worker_processes, or autovacuum_max_workers higher
 *	  than his kernel will support, he'll find out sooner rather than later.
 *
 *	  Another reason for creating semaphores here is that the semaphore
 *	  implementation typically requires us to create semaphores in the
 *	  postmaster, not in backends.
 *
 * Note: this is NOT called by individual backends under a postmaster,
 * not even in the EXEC_BACKEND case.  The ProcGlobal and AuxiliaryProcs
 * pointers must be propagated specially for EXEC_BACKEND operation.
 */
void
InitProcGlobal(void)
{
	PGPROC	   *procs;
	PGXACT	   *pgxacts;
	int			i,
				j;
	bool		found;
	uint32		TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts;

	/* Create the ProcGlobal shared structure */
	ProcGlobal = (PROC_HDR *)
		ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
	Assert(!found);

	/*
	 * Initialize the data structures.
	 */
	ProcGlobal->spins_per_delay = DEFAULT_SPINS_PER_DELAY;
	ProcGlobal->freeProcs = NULL;
	ProcGlobal->autovacFreeProcs = NULL;
	ProcGlobal->bgworkerFreeProcs = NULL;
	ProcGlobal->startupProc = NULL;
	ProcGlobal->startupProcPid = 0;
	ProcGlobal->startupBufferPinWaitBufId = -1;
	ProcGlobal->walwriterLatch = NULL;
	ProcGlobal->checkpointerLatch = NULL;

	/*
	 * Create and initialize all the PGPROC structures we'll need.  There are
	 * five separate consumers: (1) normal backends, (2) autovacuum workers
	 * and the autovacuum launcher, (3) background workers, (4) auxiliary
	 * processes, and (5) 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;
	/* XXX allProcCount isn't really all of them; it excludes prepared xacts */
	ProcGlobal->allProcCount = MaxBackends + NUM_AUXILIARY_PROCS;
	elog(DEBUG3, "InitProcGlobal of size %d :: TID : %d", TotalProcs, GetBackendThreadId());
	if (!procs)
		ereport(FATAL,
				(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.  There is 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. 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, autovacuum and bgworkers
		 * 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.   PGPROCs for prepared transactions are added to a
		 * free list by TwoPhaseShmemInit().
		 */
		if (i < MaxConnections)
		{
			/* PGPROC for normal backend, add to freeProcs list */
			procs[i].links.next = (SHM_QUEUE *) ProcGlobal->freeProcs;
			ProcGlobal->freeProcs = &procs[i];
			//elog(DEBUG3, "freeProcs %d = %p", i, ProcGlobal->freeProcs);
			//Assert(ShmemAddrIsValid(ProcGlobal->freeProcs));
		}
		else if (i < MaxConnections + autovacuum_max_workers + 1)
		{
			/* PGPROC for AV launcher/worker, add to autovacFreeProcs list */
			procs[i].links.next = (SHM_QUEUE *) ProcGlobal->autovacFreeProcs;
			ProcGlobal->autovacFreeProcs = &procs[i];
		}
		else if (i < MaxBackends)
		{
			/* PGPROC for bgworker, add to bgworkerFreeProcs list */
			procs[i].links.next = (SHM_QUEUE *) ProcGlobal->bgworkerFreeProcs;
			ProcGlobal->bgworkerFreeProcs = &procs[i];
		}

		/* Initialize myProcLocks[] shared memory queues. */
		for (j = 0; j < NUM_LOCK_PARTITIONS; j++)
			SHMQueueInit(&(procs[i].myProcLocks[j]));
	}

	/*
	 * 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));
	SpinLockInit(ProcStructLock);
}