| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | Nitin Jadhav <nitinjadhavpostgres(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>, Stephen Frost <sfrost(at)snowman(dot)net>, Magnus Hagander <magnus(at)hagander(dot)net>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: when the startup process doesn't (logging startup delays) |
| Date: | 2021-09-29 17:43:58 |
| Message-ID: | CA+TgmoY6rBnAmyxfYoT8byiprvzMM=D_U2iTz9tGa_EdBjnB-Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Sep 29, 2021 at 1:36 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> Why is it that we set the next timeout to fire not at "now + interval"
> but at "when-it-should-have-fired-but-didn't + interval"? As a user, if
> I request a message to be logged every N milliseconds, and one
> of them is a little bit delayed, then (assuming I set it to 10s) I still
> expect the next one to occur at now+10s. I don't expect the next at
> "now+5s" if one is delayed 5s.
Well, this was my suggestion, because if you don't do this, you get
drift, which I think looks weird. Like the timestamps will be:
13:41:05.012456
13:41:15.072484
13:41:25.149632
...and it gets further and further off as it goes on.'
I guess my expectation is different from yours: I expect that if I ask
for a message every 10 seconds, the time between messages is going to
be 10s, at least on average, not 10s + however much latency the system
has.
--
Robert Haas
EDB: http://www.enterprisedb.com
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