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Make the win32 shared memory code try 10 times instead of one if

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it fails because the shared memory segment already exists. This
means it can take up to 10 seconds before it reports the error
if it *does* exist, but hopefully it will make the system capable
of restarting even when the server is under high load.
This commit is contained in:
Magnus Hagander 2009-05-05 09:48:51 +00:00
parent 9f4e9bfa9b
commit 5d540add34
1 changed files with 34 additions and 34 deletions
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36
src/backend/port/win32_shmem.c
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/port/win32_shmem.c,v 1.8 2009/05/04 08:36:40 mha Exp $
* $PostgreSQL: pgsql/src/backend/port/win32_shmem.c,v 1.9 2009/05/05 09:48:51 mha Exp $
*
*-------------------------------------------------------------------------
*/
@ -123,6 +123,7 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
HANDLE hmap,
hmap2;
char *szShareMem;
int i;
/* Room for a header? */
Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
@ -131,6 +132,14 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
UsedShmemSegAddr = NULL;
/*
* When recycling a shared memory segment, it may take a short while
* before it gets dropped from the global namespace. So re-try after
* sleeping for a second, and continue retrying 10 times.
* (both the 1 second time and the 10 retries are completely arbitrary)
*/
for (i = 0; i < 10; i++)
{
/* In case CreateFileMapping() doesn't set the error code to 0 on success */
SetLastError(0);
@ -153,31 +162,22 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
*/
if (GetLastError() == ERROR_ALREADY_EXISTS)
{
/*
* When recycling a shared memory segment, it may take a short while
* before it gets dropped from the global namespace. So re-try after
* sleeping for a second.
*/
CloseHandle(hmap); /* Close the old handle, since we got a valid
* one to the previous segment. */
Sleep(1000);
continue;
}
break;
}
/* In case CreateFileMapping() doesn't set the error code to 0 on success */
SetLastError(0);
hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, NULL, PAGE_READWRITE, 0L, (DWORD) size, szShareMem);
if (!hmap)
ereport(FATAL,
(errmsg("could not create shared memory segment: %lu", GetLastError()),
errdetail("Failed system call was CreateFileMapping(size=%lu, name=%s).",
(unsigned long) size, szShareMem)));
/*
* If the last call in the loop still returned ERROR_ALREADY_EXISTS, this shared memory
* segment exists and we assume it belongs to somebody else.
*/
if (GetLastError() == ERROR_ALREADY_EXISTS)
ereport(FATAL,
(errmsg("pre-existing shared memory block is still in use"),
errhint("Check if there are any old server processes still running, and terminate them.")));
}
free(szShareMem);