Пример #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);
		}
	}
}
Пример #2
0
/*
 * ProcQueueInit -- initialize a shared memory process queue
 */
void
ProcQueueInit(PROC_QUEUE *queue)
{
	SHMQueueInit(&(queue->links));
	queue->size = 0;
}
Пример #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);
}
Пример #4
0
/*
 * MarkAsPreparing
 *		Reserve the GID for the given transaction.
 *
 * Internally, this creates a gxact struct and puts it into the active array.
 * NOTE: this is also used when reloading a gxact after a crash; so avoid
 * assuming that we can use very much backend context.
 */
GlobalTransaction
MarkAsPreparing(TransactionId xid, const char *gid,
				TimestampTz prepared_at, Oid owner, Oid databaseid)
{
	GlobalTransaction gxact;
	int			i;

	if (strlen(gid) >= GIDSIZE)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
				 errmsg("transaction identifier \"%s\" is too long",
						gid)));

	/* fail immediately if feature is disabled */
	if (max_prepared_xacts == 0)
		ereport(ERROR,
				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
				 errmsg("prepared transactions are disabled"),
			  errhint("Set max_prepared_transactions to a nonzero value.")));

	LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);

	/*
	 * First, find and recycle any gxacts that failed during prepare. We do
	 * this partly to ensure we don't mistakenly say their GIDs are still
	 * reserved, and partly so we don't fail on out-of-slots unnecessarily.
	 */
	for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
	{
		gxact = TwoPhaseState->prepXacts[i];
		if (!gxact->valid && !TransactionIdIsActive(gxact->locking_xid))
		{
			/* It's dead Jim ... remove from the active array */
			TwoPhaseState->numPrepXacts--;
			TwoPhaseState->prepXacts[i] = TwoPhaseState->prepXacts[TwoPhaseState->numPrepXacts];
			/* and put it back in the freelist */
			gxact->proc.links.next = (SHM_QUEUE *) TwoPhaseState->freeGXacts;
			TwoPhaseState->freeGXacts = gxact;
			/* Back up index count too, so we don't miss scanning one */
			i--;
		}
	}

	/* Check for conflicting GID */
	for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
	{
		gxact = TwoPhaseState->prepXacts[i];
		if (strcmp(gxact->gid, gid) == 0)
		{
			ereport(ERROR,
					(errcode(ERRCODE_DUPLICATE_OBJECT),
					 errmsg("transaction identifier \"%s\" is already in use",
							gid)));
		}
	}

	/* Get a free gxact from the freelist */
	if (TwoPhaseState->freeGXacts == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_OUT_OF_MEMORY),
				 errmsg("maximum number of prepared transactions reached"),
				 errhint("Increase max_prepared_transactions (currently %d).",
						 max_prepared_xacts)));
	gxact = TwoPhaseState->freeGXacts;
	TwoPhaseState->freeGXacts = (GlobalTransaction) gxact->proc.links.next;

	/* Initialize it */
	MemSet(&gxact->proc, 0, sizeof(PGPROC));
	SHMQueueElemInit(&(gxact->proc.links));
	gxact->proc.waitStatus = STATUS_OK;
	/* We set up the gxact's VXID as InvalidBackendId/XID */
	gxact->proc.lxid = (LocalTransactionId) xid;
	gxact->proc.xid = xid;
	gxact->proc.xmin = InvalidTransactionId;
	gxact->proc.pid = 0;
	gxact->proc.backendId = InvalidBackendId;
	gxact->proc.databaseId = databaseid;
	gxact->proc.roleId = owner;
	gxact->proc.inCommit = false;
	gxact->proc.vacuumFlags = 0;
	gxact->proc.lwWaiting = false;
	gxact->proc.lwExclusive = false;
	gxact->proc.lwWaitLink = NULL;
	gxact->proc.waitLock = NULL;
	gxact->proc.waitProcLock = NULL;
	for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
		SHMQueueInit(&(gxact->proc.myProcLocks[i]));
	/* subxid data must be filled later by GXactLoadSubxactData */
	gxact->proc.subxids.overflowed = false;
	gxact->proc.subxids.nxids = 0;

	gxact->prepared_at = prepared_at;
	/* initialize LSN to 0 (start of WAL) */
	gxact->prepare_lsn.xlogid = 0;
	gxact->prepare_lsn.xrecoff = 0;
	gxact->owner = owner;
	gxact->locking_xid = xid;
	gxact->valid = false;
	strcpy(gxact->gid, gid);

	/* And insert it into the active array */
	Assert(TwoPhaseState->numPrepXacts < max_prepared_xacts);
	TwoPhaseState->prepXacts[TwoPhaseState->numPrepXacts++] = gxact;

	LWLockRelease(TwoPhaseStateLock);

	return gxact;
}
Пример #5
0
/* ------------------------
 * InitProc -- create a per-process data structure for this process
 * used by the lock manager on semaphore queues.
 * ------------------------
 */
void
InitProcess(IPCKey key)
{
    bool found = false;
    int pid;
    int semstat;
    unsigned long location, myOffset;
    
    /* ------------------
     * Routine called if deadlock timer goes off. See ProcSleep()
     * ------------------
     */
#ifndef WIN32
    signal(SIGALRM, HandleDeadLock);
#endif /* WIN32 we'll have to figure out how to handle this later */

    SpinAcquire(ProcStructLock);
    
    /* attach to the free list */
    ProcGlobal = (PROC_HDR *)
	ShmemInitStruct("Proc Header",(unsigned)sizeof(PROC_HDR),&found);
    if (!found) {
	/* this should not happen. InitProcGlobal() is called before this. */
	elog(WARN, "InitProcess: Proc Header uninitialized");
    }
    
    if (MyProc != NULL)
	{
	    SpinRelease(ProcStructLock);
	    elog(WARN,"ProcInit: you already exist");
	    return;
	}
    
    /* try to get a proc from the free list first */
    
    myOffset = ProcGlobal->freeProcs;
    
    if (myOffset != INVALID_OFFSET)
	{
	    MyProc = (PROC *) MAKE_PTR(myOffset);
	    ProcGlobal->freeProcs = MyProc->links.next;
	}
    else
	{
	    /* have to allocate one.  We can't use the normal binding
	     * table mechanism because the proc structure is stored
	     * by PID instead of by a global name (need to look it
	     * up by PID when we cleanup dead processes).
	     */
	    
	    MyProc = (PROC *) ShmemAlloc((unsigned)sizeof(PROC));
	    if (! MyProc)
		{
		    SpinRelease(ProcStructLock);
		    elog (FATAL,"cannot create new proc: out of memory");
		}
	    
	    /* this cannot be initialized until after the buffer pool */
	    SHMQueueInit(&(MyProc->lockQueue));
	    MyProc->procId = ProcGlobal->numProcs;
	    ProcGlobal->numProcs++;
	}
    
    /*
     * zero out the spin lock counts and set the sLocks field for
     * ProcStructLock to 1 as we have acquired this spinlock above but 
     * didn't record it since we didn't have MyProc until now.
     */
    memset(MyProc->sLocks, 0, sizeof(MyProc->sLocks));
    MyProc->sLocks[ProcStructLock] = 1;


    if (IsUnderPostmaster) {
	IPCKey semKey;
	int semNum;
	int semId;
	union semun semun;

	ProcGetNewSemKeyAndNum(&semKey, &semNum);
	
	semId = IpcSemaphoreCreate(semKey,
				   PROC_NSEMS_PER_SET,
				   IPCProtection,
				   IpcSemaphoreDefaultStartValue,
				   0,
				   &semstat);
	/*
	 * we might be reusing a semaphore that belongs to a dead
	 * backend. So be careful and reinitialize its value here.
	 */
	semun.val = IpcSemaphoreDefaultStartValue;
	semctl(semId, semNum, SETVAL, semun);

	IpcSemaphoreLock(semId, semNum, IpcExclusiveLock);
	MyProc->sem.semId = semId;
	MyProc->sem.semNum = semNum;
	MyProc->sem.semKey = semKey;
    } else {
	MyProc->sem.semId = -1;
    }
    
    /* ----------------------
     * Release the lock.
     * ----------------------
     */
    SpinRelease(ProcStructLock);
    
    MyProc->pid = 0;
#if 0
    MyProc->pid = MyPid;
#endif
    
    /* ----------------
     * Start keeping spin lock stats from here on.  Any botch before
     * this initialization is forever botched
     * ----------------
     */
    memset(MyProc->sLocks, 0, MAX_SPINS*sizeof(*MyProc->sLocks));
    
    /* -------------------------
     * Install ourselves in the binding table.  The name to
     * use is determined by the OS-assigned process id.  That
     * allows the cleanup process to find us after any untimely
     * exit.
     * -------------------------
     */
    pid = getpid();
    location = MAKE_OFFSET(MyProc);
    if ((! ShmemPIDLookup(pid,&location)) || (location != MAKE_OFFSET(MyProc)))
	{
	    elog(FATAL,"InitProc: ShmemPID table broken");
	}
    
    MyProc->errType = NO_ERROR;
    SHMQueueElemInit(&(MyProc->links));
    
    on_exitpg(ProcKill, (caddr_t)pid);
    
    ProcInitialized = TRUE;
}
Пример #6
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.
 */
void
InitAuxiliaryProcess(void)
{
	PGPROC	   *auxproc;
	int			proctype;
	int			i;

	/*
	 * 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");

	/*
	 * Find a free auxproc entry. Use compare_and_swap to avoid locking.
	 */
	for (proctype = 0; proctype < NUM_AUXILIARY_PROCS; proctype++)
	{
		auxproc = &AuxiliaryProcs[proctype];
		if (compare_and_swap_32((uint32*)(&(auxproc->pid)),
								0,
								MyProcPid))
		{
			/* Find a free entry, break here. */
			break;
		}
	}
	
	if (proctype >= NUM_AUXILIARY_PROCS)
	{
		elog(FATAL, "all AuxiliaryProcs are in use");
	}

	set_spins_per_delay(ProcGlobal->spins_per_delay);

	MyProc = auxproc;
	lockHolderProcPtr = auxproc;

	/*
	 * Initialize all fields of MyProc, except for the semaphore which was
	 * prepared for us by InitProcGlobal.
	 */
	SHMQueueElemInit(&(MyProc->links));
	MyProc->waitStatus = STATUS_OK;
	MyProc->xid = InvalidTransactionId;
	MyProc->xmin = InvalidTransactionId;
	MyProc->databaseId = InvalidOid;
	MyProc->roleId = InvalidOid;
    MyProc->mppLocalProcessSerial = 0;
    MyProc->mppSessionId = 0;
    MyProc->mppIsWriter = false;
	MyProc->inVacuum = false;
	MyProc->postmasterResetRequired = true;
	MyProc->lwWaiting = false;
	MyProc->lwExclusive = false;
	MyProc->lwWaitLink = NULL;
	MyProc->waitLock = NULL;
	MyProc->waitProcLock = NULL;
	for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
		SHMQueueInit(&(MyProc->myProcLocks[i]));

	/*
	 * 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);

	MyProc->queryCommandId = -1;

	/*
	 * Arrange to clean up at process exit.
	 */
	on_shmem_exit(AuxiliaryProcKill, Int32GetDatum(proctype));
}
Пример #7
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;
	int			i;

	/*
	 * 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");

	MyProc = RemoveFirst();
	
	if (MyProc == NULL)
	{
		ereport(FATAL,
				(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
				 errmsg("sorry, too many clients already")));
	}
	
	if (gp_debug_pgproc)
	{
		elog(LOG, "allocating PGPROC entry for pid %d, freeProcs (prev offset, new offset): (%ld, %ld)",
			 MyProcPid, MAKE_OFFSET(MyProc), MyProc->links.next);
	}

	set_spins_per_delay(procglobal->spins_per_delay);

	int mppLocalProcessSerial = gp_atomic_add_32(&procglobal->mppLocalProcessCounter, 1);

	lockHolderProcPtr = MyProc;

	/* Set the next pointer to INVALID_OFFSET */
	MyProc->links.next = INVALID_OFFSET;

	/*
	 * Initialize all fields of MyProc, except for the semaphore which was
	 * prepared for us by InitProcGlobal.
	 */
	SHMQueueElemInit(&(MyProc->links));
	MyProc->waitStatus = STATUS_OK;
	MyProc->xid = InvalidTransactionId;
	MyProc->xmin = InvalidTransactionId;
	MyProc->pid = MyProcPid;
	/* databaseId and roleId will be filled in later */
	MyProc->databaseId = InvalidOid;
	MyProc->roleId = InvalidOid;
	MyProc->inVacuum = false;
	MyProc->postmasterResetRequired = true;
	MyProc->lwWaiting = false;
	MyProc->lwExclusive = false;
	MyProc->lwWaitLink = NULL;
	MyProc->waitLock = NULL;
	MyProc->waitProcLock = NULL;
	for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
		SHMQueueInit(&(MyProc->myProcLocks[i]));

    /* 
     * mppLocalProcessSerial uniquely identifies this backend process among
     * all those that our parent postmaster process creates over its lifetime. 
     *
  	 * Since we use the process serial number to decide if we should
	 * deliver a response from a server under this spin, we need to 
	 * assign it under the spin lock.
	 */
    MyProc->mppLocalProcessSerial = mppLocalProcessSerial;

    /* 
     * A nonzero gp_session_id uniquely identifies an MPP client session 
     * over the lifetime of the entry postmaster process.  A qDisp passes
     * its gp_session_id down to all of its qExecs.  If this is a qExec,
     * we have already received the gp_session_id from the qDisp.
     */
    elog(DEBUG1,"InitProcess(): gp_session_id %d", gp_session_id);
    if (Gp_role == GP_ROLE_DISPATCH && gp_session_id == -1)
        gp_session_id = mppLocalProcessSerial;
    MyProc->mppSessionId = gp_session_id;
    
    MyProc->mppIsWriter = Gp_is_writer;

	/*
	 * 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);

	/* Set wait portal (do not check if resource scheduling is enabled) */
	MyProc->waitPortalId = INVALID_PORTALID;

	MyProc->queryCommandId = -1;

	/*
	 * 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
	 * the deadlock checker.
	 */
	InitDeadLockChecking();
}