Horton

Re: pgbench: could not connect to server: Resource temporarily unavailable

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: Andrew Dunstan <andrew@dunslane.net>, Kevin McKibbin <kevinmckibbin123@gmail.com>, pgsql-performance@lists.postgresql.org
Date: 2022-08-21T22:30:17Z
Lists: pgsql-performance 
On Mon, Aug 22, 2022 at 9:48 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> It's also pretty unclear why the kernel would want to return
> EAGAIN instead of letting the nonblock connection path do the
> waiting, which is why I'm suspecting a bug rather than designed
> behavior.

Could it be that it fails like that if the listen queue is full on the
other side?

https://github.com/torvalds/linux/blob/master/net/unix/af_unix.c#L1493

If it's something like that, maybe increasing
/proc/sys/net/core/somaxconn would help?  I think older kernels only
had 128 here.

Commits

  1. Doc: document possible need to raise kernel's somaxconn limit.

  2. Doc: prefer sysctl to /proc/sys in docs and comments.

  3. Remove our artificial PG_SOMAXCONN limit on listen queue length.

  4. Instead of believing SOMAXCONN from the system header files (which is