[SOLVED] Querying verify_cache with postmap often waits minutes for a read lock

larsen

Member
Feb 28, 2020
87
8
8
When I run
Code:
postmap -q jondoe@example.com btree:/var/lib/postfix/verify_cache
this often takes up to 15 minutes or more until I get a result. The next second, it returns instantly.

I checked this with strace and noticed that it's waiting for a read lock for the "verify_cache.db". "/usr/lib/postfix/sbin/verify" is the process that is holding a write lock when the delay happens. From "man 8 verify":
Code:
as verify(8) processes are long-lived

When my postmap command returns, the verify process that existed before, has gone. A new verify process will be started shortly after.
I checked the maillog as this happened, but couldn't see anything that would cause this.

Is this expected behaviour?


Lars
 

Stoiko Ivanov

Proxmox Staff Member
Staff member
May 2, 2018
6,148
857
148
Is this expected behaviour?
Without explicitly reading through the source code - I do guess so - the database needs to be held exclusively open by the process filling the verify cache (verify(8)) and querying it

I usually recommend to copy the verify database somewhere else before quering it with postmap - as far as I remember the file is quite small and can be copied fine while postfix is running

Out of curiosity - how often do you need to do manual lookups in the verification cache and why?

I hope this helps!
 

larsen

Member
Feb 28, 2020
87
8
8
Thanks for the info!
I don't need it that often. We just recently started using PMG, so there will probably be less and less need for such things.
 
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