On 03/31/2014 10:47 PM, Simon Hobson wrote:
Nigel Kukard <[email protected]> wrote:
I'm just wondering if there's a race condition where multiple servers are
updating the quota, and one update overrides another ?
I believe the updates are done += and -= style with the delta, not updating
the actual value with value = x
ref:
https://gitlab.devlabs.linuxassist.net/policyd/policyd/blob/master/cbp/modules/Quotas.pm#L269
Rules that one out then.
Hrmmm, were you using any sort of replication ... then again, even if
you were the updates are still += , hrmm ... that and MySQL afaik uses
statement replication, not row
What we'd need to do is do a query dump and see whats going on.
I have a smaller 'cluster' of 3 machines which are all Xen PV guests, sharing a
backend. I run one instance of PolicyD on the backend and originally had my
Postfix instances accessing the single MySQL instance on the backend as well.
it all worked perfectly under the loads I was able to impose as tests - then it
all fell apart when I tried making it live.
Once under real tests, I found that MySQL lookups were failing and so there
were random mail rejections - so I had to revert back to the old server. I've
put slave MySQL instances on each host, but as yet haven't found the
out-of-hours time (or TBH, inclination to do OOH work) to try making it live
again.
Very odd indeed, I'm aware of some very large installations using combinations
of mailservers with policyd on them and dedicated mysql servers. Do you perhaps
have any logs with errors in them?
It was a while ago now, and other than Postfix logging whatever was appropriate
(typically "user unknown" IIRC) there were no errors.
I think enabling the MySQL logging should help if the queries are
failing ... also show full process list in MySQL may give some info how
many connections you're dealing with, if there was very high concurrency
you may of exceeded the number of allowed connections?
-N
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