Horton

Re: pgsql: Add kqueue(2) support to the WaitEventSet API.

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Rémi Zara <remi_zara@mac.com>, Michael Paquier <michael@paquier.xyz>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-02-24T06:53:34Z
Lists: pgsql-hackers 
On Mon, Feb 24, 2020 at 7:42 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> On Mon, Feb 24, 2020 at 12:24 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > On reflection, trying to make ReserveExternalFD serve two different
> > use-cases was pretty messy.  Here's a version that splits it into two
> > functions.  I also took the trouble to fix dblink.
>
> +    /*
> +     * We don't want more than max_safe_fds / 3 FDs to be consumed for
> +     * "external" FDs.
> +     */
> +    if (numExternalFDs < max_safe_fds / 3)

I suppose there may be users who have set ulimit -n high enough to
support an FDW workload that connects to very many hosts, who will now
need to set max_files_per_process higher to avoid the new error now
that we're doing this accounting.  That doesn't seem to be a problem
in itself, but I wonder if the error message should make it clearer
that it's our limit they hit here.

Commits

  1. Don't use EV_CLEAR for kqueue events.

  2. Fix kqueue support under debugger on macOS.

  3. Account explicitly for long-lived FDs that are allocated outside fd.c.

  4. Add kqueue(2) support to the WaitEventSet API.

  5. Introduce WaitEventSet API.