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Commit807b453

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Clean up thread management in parallel pg_dump for Windows.
Since we start the worker threads with _beginthreadex(), we should use_endthreadex() to terminate them. We got this right in the normal-exitcode path, but not so much during an error exit from a worker.In addition, be sure to apply CloseHandle to the thread handle aftereach thread exits.It's not clear that these oversights cause any user-visible problems,since the pg_dump run is about to terminate anyway. Still, it's clearlybetter to follow Microsoft's API specifications than ignore them.Also a few cosmetic cleanups in WaitForTerminatingWorkers(), includingbeing a bit less random about where to cast between uintptr_t and HANDLE,and being sure to clear the worker identity field for each dead worker(not that false matches should be possible later, but let's be careful).Original observation and patch by Armin Schöffmann, cosmetic improvementsby Michael Paquier and me. (Armin's patch also included closing socketsin ShutdownWorkersHard(), but that's been dealt with already in commitdf8d2d8.) Back-patch to 9.3 where parallel pg_dump was introduced.Discussion: <zarafa.570306bd.3418.074bf1420d8f2ba2@root.aegaeon.de>
1 parentd81ecb9 commit807b453

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2 files changed

+37
-18
lines changed

2 files changed

+37
-18
lines changed

‎src/bin/pg_dump/parallel.c

Lines changed: 36 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -327,7 +327,7 @@ ShutdownWorkersHard(ParallelState *pstate)
327327
}
328328

329329
/*
330-
* Wait forthe termination of the processes using the OS-specific method.
330+
* Wait forall workers to terminate.
331331
*/
332332
staticvoid
333333
WaitForTerminatingWorkers(ParallelState*pstate)
@@ -338,39 +338,58 @@ WaitForTerminatingWorkers(ParallelState *pstate)
338338
intj;
339339

340340
#ifndefWIN32
341+
/* On non-Windows, use wait() to wait for next worker to end */
341342
intstatus;
342343
pid_tpid=wait(&status);
343344

345+
/* Find dead worker's slot, and clear the PID field */
344346
for (j=0;j<pstate->numWorkers;j++)
345-
if (pstate->parallelSlot[j].pid==pid)
346-
slot=&(pstate->parallelSlot[j]);
347-
#else
348-
uintptr_thThread;
349-
DWORDret;
350-
uintptr_t*lpHandles=pg_malloc(sizeof(HANDLE)*pstate->numWorkers);
347+
{
348+
slot=&(pstate->parallelSlot[j]);
349+
if (slot->pid==pid)
350+
{
351+
slot->pid=0;
352+
break;
353+
}
354+
}
355+
#else/* WIN32 */
356+
/* On Windows, we must use WaitForMultipleObjects() */
357+
HANDLE*lpHandles=pg_malloc(sizeof(HANDLE)*pstate->numWorkers);
351358
intnrun=0;
359+
DWORDret;
360+
uintptr_thThread;
352361

353362
for (j=0;j<pstate->numWorkers;j++)
363+
{
354364
if (pstate->parallelSlot[j].workerStatus!=WRKR_TERMINATED)
355365
{
356-
lpHandles[nrun]=pstate->parallelSlot[j].hThread;
366+
lpHandles[nrun]=(HANDLE)pstate->parallelSlot[j].hThread;
357367
nrun++;
358368
}
359-
ret=WaitForMultipleObjects(nrun, (HANDLE*)lpHandles, false,INFINITE);
369+
}
370+
ret=WaitForMultipleObjects(nrun,lpHandles, false,INFINITE);
360371
Assert(ret!=WAIT_FAILED);
361-
hThread=lpHandles[ret-WAIT_OBJECT_0];
372+
hThread= (uintptr_t)lpHandles[ret-WAIT_OBJECT_0];
373+
free(lpHandles);
362374

375+
/* Find dead worker's slot, and clear the hThread field */
363376
for (j=0;j<pstate->numWorkers;j++)
364-
if (pstate->parallelSlot[j].hThread==hThread)
365-
slot=&(pstate->parallelSlot[j]);
366-
367-
free(lpHandles);
368-
#endif
369-
Assert(slot);
377+
{
378+
slot=&(pstate->parallelSlot[j]);
379+
if (slot->hThread==hThread)
380+
{
381+
/* For cleanliness, close handles for dead threads */
382+
CloseHandle((HANDLE)slot->hThread);
383+
slot->hThread= (uintptr_t)INVALID_HANDLE_VALUE;
384+
break;
385+
}
386+
}
387+
#endif/* WIN32 */
370388

389+
/* On all platforms, update workerStatus as well */
390+
Assert(j<pstate->numWorkers);
371391
slot->workerStatus=WRKR_TERMINATED;
372392
}
373-
Assert(HasEveryWorkerTerminated(pstate));
374393
}
375394

376395
#ifndefWIN32

‎src/bin/pg_dump/pg_backup_utils.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -149,7 +149,7 @@ exit_nicely(int code)
149149

150150
#ifdefWIN32
151151
if (parallel_init_done&&GetCurrentThreadId()!=mainThreadId)
152-
ExitThread(code);
152+
_endthreadex(code);
153153
#endif
154154

155155
exit(code);

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