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Re: UTC is not a time zone? 6+ messages / 3 participants [nested] [flat]
* Re: UTC is not a time zone? @ 2024-05-13 18:17 Tom Lane <[email protected]> 0 siblings, 1 reply; 6+ messages in thread From: Tom Lane @ 2024-05-13 18:17 UTC (permalink / raw) To: Christophe Pettus <[email protected]>; +Cc: Adrian Klaver <[email protected]>; pgsql-generallists.postgresql.org <[email protected]> Christophe Pettus <[email protected]> writes: > On May 13, 2024, at 10:48, Adrian Klaver <[email protected]> wrote: >> https://www.postgresql.org/message-id/1273542.1712326418%40sss.pgh.pa.us > Thanks! Similar, but I don't think it's that. This was a sudden change in a long-running connection that had issued a ton of ` SET TIMEZONE TO 'UTC'; ` before the failure. The underlying cause is likely roughly similar, to wit failure to read /usr/share/zoneinfo/UTC (or the Postgres-private equivalent file). The parent process would long since have cached the zone data in its memory, but this error is in a parallel worker process, which'd have to read the file for itself during startup. What's causing that I can't say. It doesn't look like we log the errno anywhere when failing to read a zone file :-( regards, tom lane ^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: UTC is not a time zone? @ 2024-05-13 18:18 Christophe Pettus <[email protected]> parent: Tom Lane <[email protected]> 0 siblings, 2 replies; 6+ messages in thread From: Christophe Pettus @ 2024-05-13 18:18 UTC (permalink / raw) To: Tom Lane <[email protected]>; +Cc: Adrian Klaver <[email protected]>; pgsql-generallists.postgresql.org <[email protected]> > On May 13, 2024, at 11:17, Tom Lane <[email protected]> wrote: > What's causing that I can't say. It doesn't look like we log the > errno anywhere when failing to read a zone file :-( File descriptor exhaustion? (Of course, that would mean something somewhere is leaking them, which is another problem.) ^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: UTC is not a time zone? @ 2024-05-13 18:26 Adrian Klaver <[email protected]> parent: Christophe Pettus <[email protected]> 1 sibling, 1 reply; 6+ messages in thread From: Adrian Klaver @ 2024-05-13 18:26 UTC (permalink / raw) To: Christophe Pettus <[email protected]>; Tom Lane <[email protected]>; +Cc: pgsql-generallists.postgresql.org <[email protected]> On 5/13/24 11:18 AM, Christophe Pettus wrote: > > >> On May 13, 2024, at 11:17, Tom Lane <[email protected]> wrote: >> What's causing that I can't say. It doesn't look like we log the >> errno anywhere when failing to read a zone file :-( > > File descriptor exhaustion? (Of course, that would mean something somewhere is leaking them, which is another problem.) If I am understanding this correctly: "The parent process would long since have cached the zone data in its memory, but this error is in a parallel worker process, which'd have to read the file for itself during startup. " Then this: "As an experiment, I'm just pounding the server with a single connection doing nothing but SET TIMEZONEs repeatedly. So far, no break, but it is *very* intermittent." May not induce the error unless there are parallel workers involved. -- Adrian Klaver [email protected] ^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: UTC is not a time zone? @ 2024-05-13 18:27 Christophe Pettus <[email protected]> parent: Adrian Klaver <[email protected]> 0 siblings, 1 reply; 6+ messages in thread From: Christophe Pettus @ 2024-05-13 18:27 UTC (permalink / raw) To: Adrian Klaver <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-generallists.postgresql.org <[email protected]> > On May 13, 2024, at 11:26, Adrian Klaver <[email protected]> wrote: > May not induce the error unless there are parallel workers involved. Indeed. I'll see about pulling together a test case that forces that. ^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: UTC is not a time zone? @ 2024-05-13 18:27 Tom Lane <[email protected]> parent: Christophe Pettus <[email protected]> 1 sibling, 0 replies; 6+ messages in thread From: Tom Lane @ 2024-05-13 18:27 UTC (permalink / raw) To: Christophe Pettus <[email protected]>; +Cc: Adrian Klaver <[email protected]>; pgsql-generallists.postgresql.org <[email protected]> Christophe Pettus <[email protected]> writes: > On May 13, 2024, at 11:17, Tom Lane <[email protected]> wrote: >> What's causing that I can't say. It doesn't look like we log the >> errno anywhere when failing to read a zone file :-( > File descriptor exhaustion? (Of course, that would mean something somewhere is leaking them, which is another problem.) Since this is in a pretty-new process, it would have to be global FD exhaustion, that is ENFILE not EMFILE. (Assuming macOS even has that concept; its BSD roots sure do, but who knows what Apple's done to it over the years.) You'd likely have seen more side-effects of such a condition. I was wondering more about permissions checks gone wrong, comparable to the antivirus-induced misbehaviors we hear about on Windows. Not that that's a comforting answer. regards, tom lane ^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: UTC is not a time zone? @ 2024-05-13 18:36 Tom Lane <[email protected]> parent: Christophe Pettus <[email protected]> 0 siblings, 0 replies; 6+ messages in thread From: Tom Lane @ 2024-05-13 18:36 UTC (permalink / raw) To: Christophe Pettus <[email protected]>; +Cc: Adrian Klaver <[email protected]>; pgsql-generallists.postgresql.org <[email protected]> Christophe Pettus <[email protected]> writes: >> On May 13, 2024, at 11:26, Adrian Klaver <[email protected]> wrote: >> May not induce the error unless there are parallel workers involved. > Indeed. I'll see about pulling together a test case that forces that. Right. Once a backend process has loaded a zone file, it caches that in a hash table that it will never flush (which is arguably a bug for other reasons, since those files aren't really immutable, but that's how it behaves today). So you've got 0 chance of hitting this via repeat SET TIMEZONE in a single backend. regards, tom lane ^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2024-05-13 18:36 UTC | newest] Thread overview: 6+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2024-05-13 18:17 Re: UTC is not a time zone? Tom Lane <[email protected]> 2024-05-13 18:18 ` Christophe Pettus <[email protected]> 2024-05-13 18:26 ` Adrian Klaver <[email protected]> 2024-05-13 18:27 ` Christophe Pettus <[email protected]> 2024-05-13 18:36 ` Tom Lane <[email protected]> 2024-05-13 18:27 ` Tom Lane <[email protected]>
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