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Commitbb98b2e

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Change win32 child-death tracking code to use a threadpool to wait for
childprocess deaths instead of using one thread per child. This drastasticallyreduces the address space usage and should allow for more backends running.Also change the win32_waitpid functionality to use an IO Completion Port forqueueing child death notices instead of using a fixed-size array.
1 parentacac68b commitbb98b2e

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2 files changed

+81
-172
lines changed

2 files changed

+81
-172
lines changed

‎src/backend/postmaster/postmaster.c‎

Lines changed: 79 additions & 171 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.542 2007/09/2622:36:30 tgl Exp $
40+
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.543 2007/10/2621:50:10 mha Exp $
4141
*
4242
* NOTES
4343
*
@@ -331,14 +331,17 @@ static void StartAutovacuumWorker(void);
331331
#ifdefEXEC_BACKEND
332332

333333
#ifdefWIN32
334-
staticvoidwin32_AddChild(pid_tpid,HANDLEhandle);
335-
staticvoidwin32_RemoveChild(pid_tpid);
336334
staticpid_twin32_waitpid(int*exitstatus);
337-
staticDWORDWINAPIwin32_sigchld_waiter(LPVOIDparam);
335+
staticvoidWINAPIpgwin32_deadchild_callback(PVOIDlpParameter,BOOLEANTimerOrWaitFired);
338336

339-
staticpid_t*win32_childPIDArray;
340-
staticHANDLE*win32_childHNDArray;
341-
staticunsigned longwin32_numChildren=0;
337+
staticHANDLEwin32ChildQueue;
338+
339+
typedefstruct
340+
{
341+
HANDLEwaitHandle;
342+
HANDLEprocHandle;
343+
DWORDprocId;
344+
}win32_deadchild_waitinfo;
342345

343346
HANDLEPostmasterHandle;
344347
#endif
@@ -899,16 +902,12 @@ PostmasterMain(int argc, char *argv[])
899902
#ifdefWIN32
900903

901904
/*
902-
* Initializethe child pid/HANDLE arrays for signal handling.
905+
* InitializeI/O completion port used to deliver list of dead children.
903906
*/
904-
win32_childPIDArray= (pid_t*)
905-
malloc(mul_size(NUM_BACKENDARRAY_ELEMS,sizeof(pid_t)));
906-
win32_childHNDArray= (HANDLE*)
907-
malloc(mul_size(NUM_BACKENDARRAY_ELEMS,sizeof(HANDLE)));
908-
if (!win32_childPIDArray|| !win32_childHNDArray)
907+
win32ChildQueue=CreateIoCompletionPort(INVALID_HANDLE_VALUE,NULL,0,1);
908+
if (win32ChildQueue==NULL)
909909
ereport(FATAL,
910-
(errcode(ERRCODE_OUT_OF_MEMORY),
911-
errmsg("out of memory")));
910+
(errmsg("could not create I/O completion port for child queue")));
912911

913912
/*
914913
* Set up a handle that child processes can use to check whether the
@@ -2072,12 +2071,7 @@ reaper(SIGNAL_ARGS)
20722071
#defineLOOPHEADER()(exitstatus = status.w_status)
20732072
#else/* WIN32 */
20742073
#defineLOOPTEST()((pid = win32_waitpid(&exitstatus)) > 0)
2075-
/*
2076-
* We need to do this here, and not in CleanupBackend, since this is
2077-
* to be called on all children when we are done with them. Could move
2078-
* to LogChildExit, but that seems like asking for future trouble...
2079-
*/
2080-
#defineLOOPHEADER()(win32_RemoveChild(pid))
2074+
#defineLOOPHEADER()
20812075
#endif/* WIN32 */
20822076
#endif/* HAVE_WAITPID */
20832077

@@ -3332,28 +3326,18 @@ internal_forkexec(int argc, char *argv[], Port *port)
33323326
inti;
33333327
intj;
33343328
charcmdLine[MAXPGPATH*2];
3335-
HANDLEchildHandleCopy;
3336-
HANDLEwaiterThread;
33373329
HANDLEparamHandle;
33383330
BackendParameters*param;
33393331
SECURITY_ATTRIBUTESsa;
33403332
charparamHandleStr[32];
3333+
win32_deadchild_waitinfo*childinfo;
33413334

33423335
/* Make sure caller set up argv properly */
33433336
Assert(argc >=3);
33443337
Assert(argv[argc]==NULL);
33453338
Assert(strncmp(argv[1],"--fork",6)==0);
33463339
Assert(argv[2]==NULL);
33473340

3348-
/* Verify that there is room in the child list */
3349-
if (win32_numChildren >=NUM_BACKENDARRAY_ELEMS)
3350-
{
3351-
elog(LOG,"no room for child entry in backend list");
3352-
/* Report same error as for a fork failure on Unix */
3353-
errno=EAGAIN;
3354-
return-1;
3355-
}
3356-
33573341
/* Set up shared memory for parameter passing */
33583342
ZeroMemory(&sa,sizeof(sa));
33593343
sa.nLength=sizeof(sa);
@@ -3463,34 +3447,34 @@ internal_forkexec(int argc, char *argv[], Port *port)
34633447
return-1;
34643448
}
34653449

3466-
if (!IsUnderPostmaster)
3467-
{
3468-
/* We are the Postmaster creating a child... */
3469-
win32_AddChild(pi.dwProcessId,pi.hProcess);
3470-
}
3471-
3472-
/* Set up the thread to handle the SIGCHLD for this process */
3473-
if (DuplicateHandle(GetCurrentProcess(),
3474-
pi.hProcess,
3475-
GetCurrentProcess(),
3476-
&childHandleCopy,
3477-
0,
3478-
FALSE,
3479-
DUPLICATE_SAME_ACCESS)==0)
3450+
/*
3451+
* Queue a waiter for to signal when this child dies. The wait will be handled automatically
3452+
* by an operating system thread pool.
3453+
*
3454+
* Note: use malloc instead of palloc, since it needs to be thread-safe. Struct will be
3455+
* free():d from the callback function that runs on a different thread.
3456+
*/
3457+
childinfo=malloc(sizeof(win32_deadchild_waitinfo));
3458+
if (!childinfo)
34803459
ereport(FATAL,
3481-
(errmsg_internal("could not duplicate child handle: error code %d",
3460+
(errcode(ERRCODE_OUT_OF_MEMORY),
3461+
errmsg("out of memory")));
3462+
3463+
childinfo->procHandle=pi.hProcess;
3464+
childinfo->procId=pi.dwProcessId;
3465+
3466+
if (!RegisterWaitForSingleObject(&childinfo->waitHandle,
3467+
pi.hProcess,
3468+
pgwin32_deadchild_callback,
3469+
childinfo,
3470+
INFINITE,
3471+
WT_EXECUTEONLYONCE |WT_EXECUTEINWAITTHREAD))
3472+
ereport(FATAL,
3473+
(errmsg_internal("could not register process for wait: error code %d",
34823474
(int)GetLastError())));
34833475

3484-
waiterThread=CreateThread(NULL,64*1024,win32_sigchld_waiter,
3485-
(LPVOID)childHandleCopy,0,NULL);
3486-
if (!waiterThread)
3487-
ereport(FATAL,
3488-
(errmsg_internal("could not create sigchld waiter thread: error code %d",
3489-
(int)GetLastError())));
3490-
CloseHandle(waiterThread);
3476+
/* Don't close pi.hProcess here - the wait thread needs access to it */
34913477

3492-
if (IsUnderPostmaster)
3493-
CloseHandle(pi.hProcess);
34943478
CloseHandle(pi.hThread);
34953479

34963480
returnpi.dwProcessId;
@@ -4500,137 +4484,61 @@ ShmemBackendArrayRemove(pid_t pid)
45004484

45014485
#ifdefWIN32
45024486

4503-
/*
4504-
* Note: The following three functions must not be interrupted (eg. by
4505-
* signals). As the Postgres Win32 signalling architecture (currently)
4506-
* requires polling, or APC checking functions which aren't used here, this
4507-
* is not an issue.
4508-
*
4509-
* We keep two separate arrays, instead of a single array of pid/HANDLE
4510-
* structs, to avoid having to re-create a handle array for
4511-
* WaitForMultipleObjects on each call to win32_waitpid.
4512-
*/
4513-
4514-
staticvoid
4515-
win32_AddChild(pid_tpid,HANDLEhandle)
4516-
{
4517-
Assert(win32_childPIDArray&&win32_childHNDArray);
4518-
if (win32_numChildren<NUM_BACKENDARRAY_ELEMS)
4519-
{
4520-
win32_childPIDArray[win32_numChildren]=pid;
4521-
win32_childHNDArray[win32_numChildren]=handle;
4522-
++win32_numChildren;
4523-
}
4524-
else
4525-
ereport(FATAL,
4526-
(errmsg_internal("no room for child entry with pid %lu",
4527-
(unsigned long)pid)));
4528-
}
4529-
4530-
staticvoid
4531-
win32_RemoveChild(pid_tpid)
4532-
{
4533-
inti;
4534-
4535-
Assert(win32_childPIDArray&&win32_childHNDArray);
4536-
4537-
for (i=0;i<win32_numChildren;i++)
4538-
{
4539-
if (win32_childPIDArray[i]==pid)
4540-
{
4541-
CloseHandle(win32_childHNDArray[i]);
4542-
4543-
/* Swap last entry into the "removed" one */
4544-
--win32_numChildren;
4545-
win32_childPIDArray[i]=win32_childPIDArray[win32_numChildren];
4546-
win32_childHNDArray[i]=win32_childHNDArray[win32_numChildren];
4547-
return;
4548-
}
4549-
}
4550-
4551-
ereport(WARNING,
4552-
(errmsg_internal("could not find child entry with pid %lu",
4553-
(unsigned long)pid)));
4554-
}
4555-
45564487
staticpid_t
45574488
win32_waitpid(int*exitstatus)
45584489
{
4490+
DWORDdwd;
4491+
ULONG_PTRkey;
4492+
OVERLAPPED*ovl;
4493+
45594494
/*
4560-
* Note: Do NOT use WaitForMultipleObjectsEx, as we don't want to run
4561-
* queued APCs here.
4495+
* Check if there are any dead children. If there are, return the pid of the first one that died.
45624496
*/
4563-
intindex;
4564-
DWORDexitCode;
4565-
DWORDret;
4566-
unsigned longoffset;
4567-
4568-
Assert(win32_childPIDArray&&win32_childHNDArray);
4569-
elog(DEBUG3,"waiting on %lu children",win32_numChildren);
4570-
4571-
for (offset=0;offset<win32_numChildren;offset+=MAXIMUM_WAIT_OBJECTS)
4497+
if (GetQueuedCompletionStatus(win32ChildQueue,&dwd,&key,&ovl,0))
45724498
{
4573-
unsigned longnum=Min(MAXIMUM_WAIT_OBJECTS,win32_numChildren-offset);
4574-
4575-
ret=WaitForMultipleObjects(num,&win32_childHNDArray[offset], FALSE,0);
4576-
switch (ret)
4577-
{
4578-
caseWAIT_FAILED:
4579-
ereport(LOG,
4580-
(errmsg_internal("failed to wait on %lu of %lu children: error code %d",
4581-
num,win32_numChildren, (int)GetLastError())));
4582-
return-1;
4583-
4584-
caseWAIT_TIMEOUT:
4585-
/* No children (in this chunk) have finished */
4586-
break;
4587-
4588-
default:
4589-
4590-
/*
4591-
* Get the exit code, and return the PID of, the respective
4592-
* process
4593-
*/
4594-
index=offset+ret-WAIT_OBJECT_0;
4595-
Assert(index >=0&&index<win32_numChildren);
4596-
if (!GetExitCodeProcess(win32_childHNDArray[index],&exitCode))
4597-
{
4598-
/*
4599-
* If we get this far, this should never happen, but, then
4600-
* again... No choice other than to assume a catastrophic
4601-
* failure.
4602-
*/
4603-
ereport(FATAL,
4604-
(errmsg_internal("failed to get exit code for child %lu",
4605-
(unsigned long)win32_childPIDArray[index])));
4606-
}
4607-
*exitstatus= (int)exitCode;
4608-
returnwin32_childPIDArray[index];
4609-
}
4499+
*exitstatus= (int)key;
4500+
returndwd;
46104501
}
46114502

4612-
/* No children have finished */
46134503
return-1;
46144504
}
46154505

46164506
/*
4617-
* Note! Code below executes onseparate threads, one for
4618-
*each child process created
4507+
* Note! Code below executes ona thread pool! All operations must
4508+
*be thread safe! Note that elog() and friends must *not* be used.
46194509
*/
4620-
staticDWORDWINAPI
4621-
win32_sigchld_waiter(LPVOIDparam)
4510+
staticvoidWINAPI
4511+
pgwin32_deadchild_callback(PVOIDlpParameter,BOOLEANTimerOrWaitFired)
46224512
{
4623-
HANDLEprocHandle= (HANDLE)param;
4513+
win32_deadchild_waitinfo*childinfo= (win32_deadchild_waitinfo*)lpParameter;
4514+
DWORDexitcode;
46244515

4625-
DWORDr=WaitForSingleObject(procHandle,INFINITE);
4516+
if (TimerOrWaitFired)
4517+
return;/* timeout. Should never happen, since we use INFINITE as timeout value. */
46264518

4627-
if (r==WAIT_OBJECT_0)
4628-
pg_queue_signal(SIGCHLD);
4629-
else
4630-
write_stderr("could not wait on child process handle: error code %d\n",
4631-
(int)GetLastError());
4632-
CloseHandle(procHandle);
4633-
return0;
4519+
/* Remove handle from wait - required even though it's set to wait only once */
4520+
UnregisterWaitEx(childinfo->waitHandle,NULL);
4521+
4522+
if (!GetExitCodeProcess(childinfo->procHandle,&exitcode))
4523+
{
4524+
/*
4525+
* Should never happen. Inform user and set a fixed exitcode.
4526+
*/
4527+
write_stderr("could not read exitcode for process\n");
4528+
exitcode=255;
4529+
}
4530+
4531+
if (!PostQueuedCompletionStatus(win32ChildQueue,childinfo->procId, (ULONG_PTR)exitcode,NULL))
4532+
write_stderr("could not post child completion status\n");
4533+
4534+
/* Handle is per-process, so we close it here instead of in the originating thread */
4535+
CloseHandle(childinfo->procHandle);
4536+
4537+
/* Free struct that was allocated before the call to RegisterWaitForSingleObject() */
4538+
free(childinfo);
4539+
4540+
/* Queue SIGCHLD signal */
4541+
pg_queue_signal(SIGCHLD);
46344542
}
46354543

46364544
#endif/* WIN32 */

‎src/include/port/win32.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,10 @@
1-
/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.76 2007/07/25 12:22:53 mha Exp $ */
1+
/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.77 2007/10/26 21:50:10 mha Exp $ */
22

33
#if defined(_MSC_VER)|| defined(__BORLANDC__)
44
#defineWIN32_ONLY_COMPILER
55
#endif
66

7+
#define_WIN32_WINNT 0x0500
78
/*
89
* Always build with SSPI support. Keep it as a #define in case
910
* we want a switch to disable it sometime in the future.

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