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From: Tom Lane <[email protected]>
To: Andres Freund <[email protected]>
Cc: Tomas Vondra <[email protected]>
Cc: Jelte Fennema-Nio <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: Bump soft open file limit (RLIMIT_NOFILE) to hard limit on startup
Date: Tue, 11 Feb 2025 17:55:39 -0500
Message-ID: <[email protected]> (raw)
In-Reply-To: <xvd2cyrtd4wk42ugweydxfcy3bwtaymu4gqmky5fpfcu6xia4m@qbgeq23yncch>
References: <CAGECzQQh6VSy3KG4pN1d=h9J=D1rStFCMR+t7yh_Kwj-g87aLQ@mail.gmail.com>
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	<xvd2cyrtd4wk42ugweydxfcy3bwtaymu4gqmky5fpfcu6xia4m@qbgeq23yncch>

Andres Freund <[email protected]> writes:
> In the current version of the AIO patchset, the creation of those io_uring
> instances does happen as part of an shmem init callback, as the io uring
> creation also sets up queues visible in shmem.

Hmm.

> So the issue would actually be that we're currently doing set_max_safe_fds()
> too late, not too early :/

Well, we'd rather set_max_safe_fds happen after semaphore creation,
so that it doesn't have to be explicitly aware of whether semaphores
consume FDs.  Could we have it be aware of how many FDs *will be*
needed for io_uring, but postpone creation of those until after we
jack up RLIMIT_NOFILE?

I guess the other way would be to have two rounds of RLIMIT_NOFILE
adjustment, before and after shmem creation.  That seems ugly but
shouldn't be very time-consuming.

			regards, tom lane

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