Distinguish between AcquireExternalFD and epoll_create1 / kqueue failing

anarazel · anarazel · commit b8f9afc81f26 · 2024-11-26T12:44:47.000-05:00
The error messages in CreateWaitEventSet() made it hard to know whether the syscall or AcquireExternalFD() failed. This is particularly relevant because AcquireExternalFD() imposes a lower limit than what would cause syscalls fail with EMFILE. I did not change the message in libpqsrv_connect_prepare(), which is the one other use of AcquireExternalFD() in our codebase, as the error message already is less ambiguous. Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/xjjx7r4xa7beixuu4qtkdhnwdbchrrpo3gaeb3jsbinvvdiat5@cwjw55mna5of
diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
@@ -811,10 +811,7 @@ CreateWaitEventSet(ResourceOwner resowner, int nevents)
 
 #if defined(WAIT_USE_EPOLL)
 	if (!AcquireExternalFD())
-	{
-		/* treat this as though epoll_create1 itself returned EMFILE */
-		elog(ERROR, "epoll_create1 failed: %m");
-	}
+		elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: %m");
 	set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 	if (set->epoll_fd < 0)
 	{
@@ -823,10 +820,7 @@ CreateWaitEventSet(ResourceOwner resowner, int nevents)
 	}
 #elif defined(WAIT_USE_KQUEUE)
 	if (!AcquireExternalFD())
-	{
-		/* treat this as though kqueue itself returned EMFILE */
-		elog(ERROR, "kqueue failed: %m");
-	}
+		elog(ERROR, "AcquireExternalFD, for kqueue, failed: %m");
 	set->kqueue_fd = kqueue();
 	if (set->kqueue_fd < 0)
 	{
