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Tweak startup sequence so that running out of PROC array slots is

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detected sooner in backend startup, and is treated as an expected error
(it gives 'Sorry, too many clients already' now).  This allows us not
to have to enforce the MaxBackends limit exactly in the postmaster.
Also, remove ProcRemove() and fold its functionality into ProcKill().
There's no good reason for a backend not to be responsible for removing
its PROC entry, and there are lots of good reasons for the postmaster
not to be touching shared-memory data structures.
This commit is contained in:
Tom Lane
2001-06-16 22:58:17 +00:00
parent 668db147d5
commit 2917f0a5dd
6 changed files with 85 additions and 92 deletions
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52
src/backend/storage/lmgr/proc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.102 2001/05/25 15:45:33 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.103 2001/06/16 22:58:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -390,45 +390,16 @@ ProcReleaseLocks(bool isCommit)
!isCommit, GetCurrentTransactionId());
}
/*
* ProcRemove -
* called by the postmaster to clean up the global tables after a
* backend exits. This also frees up the proc's wait semaphore.
*/
bool
ProcRemove(int pid)
{
SHMEM_OFFSET location;
PROC *proc;
location = ShmemPIDDestroy(pid);
if (location == INVALID_OFFSET)
return FALSE;
proc = (PROC *) MAKE_PTR(location);
SpinAcquire(ProcStructLock);
ProcFreeSem(proc->sem.semId, proc->sem.semNum);
/* Add PROC struct to freelist so space can be recycled in future */
proc->links.next = ProcGlobal->freeProcs;
ProcGlobal->freeProcs = MAKE_OFFSET(proc);
SpinRelease(ProcStructLock);
return TRUE;
}
/*
* ProcKill() -- Destroy the per-proc data structure for
* this process. Release any of its held spin locks.
*
* This is done inside the backend process before it exits.
* ProcRemove, above, will be done by the postmaster afterwards.
*/
static void
ProcKill(void)
{
SHMEM_OFFSET location;
Assert(MyProc);
/* Release any spinlocks I am holding */
@ -445,9 +416,26 @@ ProcKill(void)
LockReleaseAll(USER_LOCKMETHOD, MyProc, true, InvalidTransactionId);
#endif
/* Remove my PROC struct from the shmem hash table */
location = ShmemPIDDestroy(MyProcPid);
Assert(location != INVALID_OFFSET);
Assert(MyProc == (PROC *) MAKE_PTR(location));
SpinAcquire(ProcStructLock);
/* Free up my wait semaphore */
ProcFreeSem(MyProc->sem.semId, MyProc->sem.semNum);
/* Add PROC struct to freelist so space can be recycled in future */
MyProc->links.next = ProcGlobal->freeProcs;
ProcGlobal->freeProcs = MAKE_OFFSET(MyProc);
SpinRelease(ProcStructLock);
MyProc = NULL;
}
/*
* ProcQueue package: routines for putting processes to sleep
* and waking them up