php_fpm stops with no useful logging - how to troubleshoot?

[jpre...@eepycat.org]

I'm not looking for someone to solve this for me, at least not yet. I
want to give this a solid try myself. The problem is I have no
experience with this level of system troubleshooting; I'm very well
versed on the network infrastructure side of things, much less so on
FreeBSD troubleshooting capabilities. So, I'm just looking for guidance
to get me started, lest I wander for too long in the wrong direction.

I'm running a mail stack (postfix, dovecot, amavsid, roundcube with
nginx) in a VNET jail on 14.2-p3, and most everything is humming along
nicely. Once every 2-3 days, the php_fpm process (php version 8.3.20)
stops and requires a manual restart via `service php_fpm start`. There's
nothing useful in any logs, and this is where I'm feeling stuck.

Any nudging in the right direction to start troubleshooting would be
greatly appreciated. I'd like to use this as an opportunity to learn how
to approach application troubleshooting on FreeBSD, and hopefully be a
more useful participant in this community in the future.

Cheers
-Justin

[jpre...@eepycat.org]

I've received a direct reply with a few tips, appreciate it

Debug logging hasn't shown anything, and monitoring doesn't show any
issues with resource availability (CPU / RAM / disk) that could be
impacting this. I've updated to php 8.3.21 from 8.3.20 and will monitor.

Another reason for this update - I've realized my SPF hard fail setting
may have caused some mailing list receivers to not get my initial
message. It's now softfail based on recommendations here:
https://www.m3aawg.org/sites/default/files/m3aawg-email-authentication-recommended-best-practices-09-2020.pdf

-Justin