Quoting Wietse Venema ([email protected]):
> > Since the mailq calls are done asynchronous two calls might come in
> > within the same second. I had a few 'showq -t unix -u -c' procs
> > running, killed them, and now it's fast again. Next time i'll try
> > and see if they give any usefull strace output.
>
> If you run mailq commands in parallel, then everything will get very
> slow with disk seek operations unless you have an SSD drive. It is
> like running multple "find" commands. Don't do that.
Okay, sure. But this server does not handle thousands of mails in the
queue. Just a few (~10) were queued when this issue popped up.
So i wonder why mailq takes so long to finish in the first place.
Even if i started 50 mailq procs i'd expect them to finish sooner.
Also, this doesn't explain why smtp accept (eg, telnet localhost 25)
took well over 20 seconds to present the SMTP banner. System load at
the time was 0.00 and a restart of the entire Postfix system magically
makes everything fast again.
Could you shed some light on the dark corners i might need to
investigate when this pops up again? It's a sporadic issue,
unfortunately.
> As a safety feature, the number of showq processes is intentionally
> limited in master.cf. Now you know why.
Out-of-the-box master.cf lists showq as
"showq unix n - - - - showq"
in master.cf on this install.
-Sndr.
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