From ce07aff48f15a2fa4f91bc67efe1cb3cc9c14bcf Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 30 Apr 2018 16:19:51 -0400
Subject: [PATCH] Further effort at preventing memory map dump from affecting
the results.
Rather than elog'ing immediately, push the map data into a preallocated
StringInfo. Perhaps this will prevent some of the mid-operation
allocations that are evidently happening now.
Discussion: https://postgr.es/m/25495.1524517820@sss.pgh.pa.us
---
src/backend/port/win32_shmem.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c
index 9e42665ed62..dd66756b991 100644
--- a/src/backend/port/win32_shmem.c
+++ b/src/backend/port/win32_shmem.c
@@ -12,6 +12,7 @@
*/
#include "postgres.h"
+#include "lib/stringinfo.h"
#include "miscadmin.h"
#include "storage/dsm.h"
#include "storage/ipc.h"
@@ -54,13 +55,17 @@ mi_state(DWORD code)
return "???";
}
+/*
+ * Append memory dump to buf. To avoid affecting the memory map mid-run,
+ * buf should be preallocated to be bigger than needed.
+ */
static void
-dumpmem(const char *reason)
+dumpmem(StringInfo buf, const char *reason)
{
char *addr = 0;
MEMORY_BASIC_INFORMATION mi;
- elog(LOG, "%s memory map", reason);
+ appendStringInfo(buf, "%s memory map:", reason);
do
{
memset(&mi, 0, sizeof(mi));
@@ -68,12 +73,13 @@ dumpmem(const char *reason)
{
if (GetLastError() == ERROR_INVALID_PARAMETER)
break;
- elog(LOG, "VirtualQuery failed: %lu", GetLastError());
+ appendStringInfo(buf, "\nVirtualQuery failed: %lu", GetLastError());
break;
}
- elog(LOG, "0x%p+0x%p %s (alloc 0x%p) %s",
- mi.BaseAddress, (void *) mi.RegionSize,
- mi_type(mi.Type), mi.AllocationBase, mi_state(mi.State));
+ appendStringInfo(buf, "\n0x%p+0x%p %s (alloc 0x%p) %s",
+ mi.BaseAddress, (void *) mi.RegionSize,
+ mi_type(mi.Type), mi.AllocationBase,
+ mi_state(mi.State));
addr += mi.RegionSize;
} while (addr > 0);
}
@@ -442,11 +448,16 @@ PGSharedMemoryReAttach(void)
{
PGShmemHeader *hdr;
void *origUsedShmemSegAddr = UsedShmemSegAddr;
+ StringInfoData buf;
Assert(UsedShmemSegAddr != NULL);
Assert(IsUnderPostmaster);
- dumpmem("before VirtualFree");
+ /* Ensure buf is big enough that it won't grow mid-operation */
+ initStringInfo(&buf);
+ enlargeStringInfo(&buf, 128 * 1024);
+
+ dumpmem(&buf, "before VirtualFree");
/*
* Release memory region reservation that was made by the postmaster
@@ -455,20 +466,19 @@ PGSharedMemoryReAttach(void)
elog(FATAL, "failed to release reserved memory region (addr=%p): error code %lu",
UsedShmemSegAddr, GetLastError());
- dumpmem("after VirtualFree");
+ dumpmem(&buf, "after VirtualFree");
hdr = (PGShmemHeader *) MapViewOfFileEx(UsedShmemSegID, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0, UsedShmemSegAddr);
if (!hdr)
{
DWORD maperr = GetLastError();
- dumpmem("after failed MapViewOfFileEx");
+ dumpmem(&buf, "after failed MapViewOfFileEx");
+ elog(LOG, "%s", buf.data);
elog(FATAL, "could not reattach to shared memory (key=%p, addr=%p): error code %lu",
UsedShmemSegID, UsedShmemSegAddr, maperr);
}
- else
- dumpmem("after MapViewOfFileEx");
if (hdr != origUsedShmemSegAddr)
elog(FATAL, "reattaching to shared memory returned unexpected address (got %p, expected %p)",
hdr, origUsedShmemSegAddr);
@@ -476,6 +486,8 @@ PGSharedMemoryReAttach(void)
elog(FATAL, "reattaching to shared memory returned non-PostgreSQL memory");
dsm_set_control_handle(hdr->dsm_control);
+ pfree(buf.data);
+
UsedShmemSegAddr = hdr; /* probably redundant */
}
--
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