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authorMagnus Hagander2009-05-05 09:48:51 +0000
committerMagnus Hagander2009-05-05 09:48:51 +0000
commitbc07a4323684e2fb63a145d6e46a9d8b1416f240 (patch)
tree3d3b327345c6f62330362dde6f50d9043f0ded1f
parent271fe3c0cb147d878df905e7b169b85d45097faa (diff)
Make the win32 shared memory code try 10 times instead of one if
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.
-rw-r--r--src/backend/port/win32_shmem.c66
1 files changed, 33 insertions, 33 deletions
diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c
index 80700950aa..05c35eb009 100644
--- a/src/backend/port/win32_shmem.c
+++ b/src/backend/port/win32_shmem.c
@@ -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)));
@@ -131,54 +132,53 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
UsedShmemSegAddr = NULL;
- /* In case CreateFileMapping() doesn't set the error code to 0 on success */
- SetLastError(0);
-
- hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, /* Use the pagefile */
- NULL, /* Default security attrs */
- PAGE_READWRITE, /* Memory is Read/Write */
- 0L, /* Size Upper 32 Bits */
- (DWORD) size, /* Size Lower 32 bits */
- 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 segment already existed, CreateFileMapping() will return a
- * handle to the existing one.
+ * 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)
*/
- if (GetLastError() == ERROR_ALREADY_EXISTS)
+ for (i = 0; i < 10; i++)
{
- /*
- * 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);
-
/* 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);
+ hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, /* Use the pagefile */
+ NULL, /* Default security attrs */
+ PAGE_READWRITE, /* Memory is Read/Write */
+ 0L, /* Size Upper 32 Bits */
+ (DWORD) size, /* Size Lower 32 bits */
+ 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 segment already existed, CreateFileMapping() will return a
+ * handle to the existing one.
+ */
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.")));
+ {
+ CloseHandle(hmap); /* Close the old handle, since we got a valid
+ * one to the previous segment. */
+ Sleep(1000);
+ continue;
+ }
+ break;
}
+ /*
+ * 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);
/*