| From: | Masahiro Ikeda <ikedamsh(at)oss(dot)nttdata(dot)com> |
|---|---|
| To: | Michael Paquier <michael(at)paquier(dot)xyz>, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Why are wait events not reported even though it reads/writes a timeline history file? |
| Date: | 2020-04-28 08:42:32 |
| Message-ID: | 24cc681e7048f984e490f5d01f7ead19@oss.nttdata.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 2020-04-28 15:09, Michael Paquier wrote:
> On Tue, Apr 28, 2020 at 02:49:00PM +0900, Fujii Masao wrote:
>> Isn't it safer to report the wait event during fgets() rather than
>> putting
>> those calls around the whole loop, like other code does? For example,
>> writeTimeLineHistory() reports the wait event during read() rather
>> than
>> whole loop.
>
> Yeah, I/O wait events should be taken only during the duration of the
> system calls. Particularly here, you may finish with an elog() that
> causes the wait event to be set longer than it should, leading to a
> rather incorrect state if a snapshot of pg_stat_activity is taken.
> --
Thanks for your comments.
I fixed it to report the wait event during fgets() only.
Please review the v2 patch I attached.
Regard,
--
Masahiro Ikeda
| Attachment | Content-Type | Size |
|---|---|---|
| v2-0001-Fix-to-report-wait-events-about-timeline-history-.patch | text/x-diff | 1.7 KB |
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