On Mon, Aug 10, 2009 at 19:33, Magnus Hagander<mag...@hagander.net> wrote: > On Mon, Aug 10, 2009 at 16:58, Tom Lane<t...@sss.pgh.pa.us> wrote: >> Magnus Hagander <mag...@hagander.net> writes: >>> On Mon, Aug 10, 2009 at 16:10, Tom Lane<t...@sss.pgh.pa.us> wrote: >>>> 8.2 as well, no? >> >>> 8.2 has a different shmem implementation - the one that emulates sysv >>> shmem. The patch will need to be changed around for that, and I >>> haven't looked at that. It may be worthwhile to do that, but it's a >>> separate patch, so let's get it out in 8.3 and 8.4 first. >> >> If it's at all hard to do, I could see deprecating 8.2 for Windows >> instead. > > I haven't looked at how much work it would be at all yet. So let's do > that before we decide to deprecate anything. As mentioned downthread, > 8.2 is a very widespread release, and we really want to avoid > deprecating it.
Here's an attempt at a backport to 8.2. I haven't examined it in detail, but it passes "make check" on mingw. Comments? -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/
*** a/src/backend/port/sysv_shmem.c --- b/src/backend/port/sysv_shmem.c *************** *** 49,54 **** typedef int IpcMemoryId; /* shared memory ID returned by shmget(2) */ --- 49,57 ---- unsigned long UsedShmemSegID = 0; void *UsedShmemSegAddr = NULL; + #ifdef WIN32 + Size UsedShmemSegSize = 0; + #endif static void *InternalIpcMemoryCreate(IpcMemoryKey memKey, Size size); static void IpcMemoryDetach(int status, Datum shmaddr); *************** *** 403,408 **** PGSharedMemoryCreate(Size size, bool makePrivate, int port) --- 406,412 ---- /* Save info for possible future use */ UsedShmemSegAddr = memAddress; + UsedShmemSegSize = size; UsedShmemSegID = (unsigned long) NextShmemSegID; return hdr; *** a/src/backend/port/win32/shmem.c --- b/src/backend/port/win32/shmem.c *************** *** 12,19 **** --- 12,22 ---- */ #include "postgres.h" + #include "miscadmin.h" static DWORD s_segsize = 0; + extern void *UsedShmemSegAddr; + extern Size UsedShmemSegSize; /* Detach from a shared mem area based on its address */ int *************** *** 29,34 **** shmdt(const void *shmaddr) --- 32,44 ---- void * shmat(int memId, void *shmaddr, int flag) { + /* Release the memory region reserved in the postmaster */ + if (IsUnderPostmaster) + { + if (VirtualFree(shmaddr, 0, MEM_RELEASE) == 0) + elog(FATAL, "failed to release reserved memory region (addr=%p): %lu", + shmaddr, GetLastError()); + } /* TODO -- shmat needs to count # attached to shared mem */ void *lpmem = MapViewOfFileEx((HANDLE) memId, FILE_MAP_WRITE | FILE_MAP_READ, *************** *** 128,130 **** shmget(int memKey, int size, int flag) --- 138,190 ---- return (int) hmap; } + + /* + * pgwin32_ReserveSharedMemoryRegion(hChild) + * + * Reserve the memory region that will be used for shared memory in a child + * process. It is called before the child process starts, to make sure the + * memory is available. + * + * Once the child starts, DLLs loading in different order or threads getting + * scheduled differently may allocate memory which can conflict with the + * address space we need for our shared memory. By reserving the shared + * memory region before the child starts, and freeing it only just before we + * attempt to get access to the shared memory forces these allocations to + * be given different address ranges that don't conflict. + * + * NOTE! This function executes in the postmaster, and should for this + * reason not use elog(FATAL) since that would take down the postmaster. + */ + int + pgwin32_ReserveSharedMemoryRegion(HANDLE hChild) + { + void *address; + + Assert(UsedShmemSegAddr != NULL); + Assert(UsedShmemSegSize != 0); + + address = VirtualAllocEx(hChild, UsedShmemSegAddr, UsedShmemSegSize, + MEM_RESERVE, PAGE_READWRITE); + if (address == NULL) { + /* Don't use FATAL since we're running in the postmaster */ + elog(LOG, "could not reserve shared memory region (addr=%p) for child %lu: %lu", + UsedShmemSegAddr, hChild, GetLastError()); + return false; + } + if (address != UsedShmemSegAddr) + { + /* + * Should never happen - in theory if allocation granularity causes strange + * effects it could, so check just in case. + * + * Don't use FATAL since we're running in the postmaster. + */ + elog(LOG, "reserved shared memory region got incorrect address %p, expected %p", + address, UsedShmemSegAddr); + VirtualFreeEx(hChild, address, 0, MEM_RELEASE); + return false; + } + + return true; + } *** a/src/backend/postmaster/postmaster.c --- b/src/backend/postmaster/postmaster.c *************** *** 3184,3190 **** internal_forkexec(int argc, char *argv[], Port *port) return -1; /* log made by save_backend_variables */ } ! /* Drop the shared memory that is now inherited to the backend */ if (!UnmapViewOfFile(param)) elog(LOG, "could not unmap view of backend parameter file: error code %d", (int) GetLastError()); --- 3184,3190 ---- return -1; /* log made by save_backend_variables */ } ! /* Drop the parameter shared memory that is now inherited to the backend */ if (!UnmapViewOfFile(param)) elog(LOG, "could not unmap view of backend parameter file: error code %d", (int) GetLastError()); *************** *** 3193,3198 **** internal_forkexec(int argc, char *argv[], Port *port) --- 3193,3217 ---- (int) GetLastError()); /* + * Reserve the memory region used by our main shared memory segment before we + * resume the child process. + */ + if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess)) + { + /* + * Failed to reserve the memory, so terminate the newly created + * process and give up. + */ + if (!TerminateProcess(pi.hProcess, 255)) + ereport(ERROR, + (errmsg_internal("could not terminate process that failed to reserve memory: error code %d", + (int) GetLastError()))); + CloseHandle(pi.hProcess); + CloseHandle(pi.hThread); + return -1; /* logging done made by pgwin32_ReserveSharedMemoryRegion() */ + } + + /* * Now that the backend variables are written out, we start the child * thread so it can start initializing while we set up the rest of the * parent state. *** a/src/include/port/win32.h --- b/src/include/port/win32.h *************** *** 263,268 **** extern int pgwin32_is_admin(void); --- 263,271 ---- extern int pgwin32_is_service(void); #endif + /* in backend/port/win32/shmem.c */ + extern int pgwin32_ReserveSharedMemoryRegion(HANDLE); + /* in port/win32error.c */ extern void _dosmaperr(unsigned long);
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