Hi, On 2024-11-26 11:35:56 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > I think it's rather confusing to claim that epoll_create1() failed when we > > didn't even call it. > > Why are we misattributing the failure to a system call that we didn't make? > > I think the idea was that this mechanism is equivalent to an EMFILE > limit. But if you feel a need to make a distinction, this seems fine: > > > elog(ERROR, "AcquireExternalFD, for epoll_create1, failed: > > %m"); > > You should probably check all of 3d475515a, because I think > I applied the same idea in more than one place.
Yea, there's another equivalent message for kqueue a few lines below. The commit also added uses of AcquireExternalFD() to dblink and postgres_fdw ( since migrated to libpq-be-fe-helpers.h), but I don't think those need improving in the same way. They never made it sound like it was a syscall itself failing. Greetings, Andres Freund
>From 6ba3876a01c89884fa718a407bf7cb3094bd9106 Mon Sep 17 00:00:00 2001 From: Andres Freund <and...@anarazel.de> Date: Tue, 26 Nov 2024 12:20:59 -0500 Subject: [PATCH v1] Distinguish between AcquireExternalFD and epoll_create1 / kqueue failing 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. Discussion: https://postgr.es/m/xjjx7r4xa7beixuu4qtkdhnwdbchrrpo3gaeb3jsbinvvdiat5@cwjw55mna5of --- src/backend/storage/ipc/latch.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c index 608eb66abed..78d43f07d03 100644 --- a/src/backend/storage/ipc/latch.c +++ b/src/backend/storage/ipc/latch.c @@ -813,7 +813,7 @@ CreateWaitEventSet(ResourceOwner resowner, int nevents) 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) @@ -825,7 +825,7 @@ CreateWaitEventSet(ResourceOwner resowner, int nevents) 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) -- 2.45.2.746.g06e570c0df.dirty
