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Cause stats processes to detach from shared memory when started, so that

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they do not prevent the postmaster from deleting the shmem segment during
a post-backend-crash restart cycle.  Per recent discussion.
This commit is contained in:
Tom Lane 2003-11-07 21:55:50 +00:00
parent 7e4a629492
commit f8a769b47a
3 changed files with 35 additions and 11 deletions
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37
src/backend/port/sysv_shmem.c
View File

@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.24 2003/10/27 18:30:07 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.25 2003/11/07 21:55:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -134,7 +134,7 @@ InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size)
/* OK, should be able to attach to the segment */
#ifdef SHM_SHARE_MMU
/* use intimate shared memory on SPARC Solaris */
/* use intimate shared memory on Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
#else
memAddress = shmat(shmid, 0, 0);
@ -244,7 +244,7 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
/* Room for a header? */
Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
/* Just attach and return the pointer */
/* If Exec case, just attach and return the pointer */
if (ExecBackend && UsedShmemSegAddr != NULL && !makePrivate)
{
if ((hdr = PGSharedMemoryAttach(UsedShmemSegID, &shmid)) == NULL)
@ -253,6 +253,9 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
return hdr;
}
/* Make sure PGSharedMemoryAttach doesn't fail without need */
UsedShmemSegAddr = NULL;
/* Loop till we find a free IPC key */
NextShmemSegID = port * 1000;
@ -326,16 +329,32 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
if (ExecBackend && UsedShmemSegAddr == NULL && !makePrivate)
{
UsedShmemSegAddr = memAddress;
UsedShmemSegID = NextShmemSegID;
}
/* Save info for possible future use */
UsedShmemSegAddr = memAddress;
UsedShmemSegID = NextShmemSegID;
return hdr;
}
/*
* PGSharedMemoryDetach
*
* Detach from the shared memory segment, if still attached. This is not
* intended for use by the process that originally created the segment
* (it will have an on_shmem_exit callback registered to do that). Rather,
* this is for subprocesses that have inherited an attachment and want to
* get rid of it.
*/
void
PGSharedMemoryDetach(void)
{
if (UsedShmemSegAddr != NULL)
{
if (shmdt(UsedShmemSegAddr) < 0)
elog(LOG, "shmdt(%p) failed: %m", UsedShmemSegAddr);
UsedShmemSegAddr = NULL;
}
}
/*
* Attach to shared memory and make sure it has a Postgres header

6
src/backend/postmaster/pgstat.c
View File

@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2003, PostgreSQL Global Development Group
*
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.45 2003/09/25 06:58:01 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.46 2003/11/07 21:55:50 tgl Exp $
* ----------
*/
#include "postgres.h"
@ -44,6 +44,7 @@
#include "utils/memutils.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/rel.h"
#include "utils/hsearch.h"
#include "utils/ps_status.h"
@ -400,6 +401,9 @@ pgstat_start(void)
/* Close the postmaster's sockets, except for pgstat link */
ClosePostmasterPorts(false);
/* Drop our connection to postmaster's shared memory, as well */
PGSharedMemoryDetach();
pgstat_main();
exit(0);

3
src/include/storage/pg_shmem.h
View File

@ -17,7 +17,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_shmem.h,v 1.7 2003/08/04 02:40:15 momjian Exp $
* $Id: pg_shmem.h,v 1.8 2003/11/07 21:55:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -44,5 +44,6 @@ extern void *UsedShmemSegAddr;
extern PGShmemHeader *PGSharedMemoryCreate(uint32 size, bool makePrivate,
int port);
extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
extern void PGSharedMemoryDetach(void);
#endif /* PG_SHMEM_H */