> Hi Stephen,
>
> Can you tell us anymore about the context, or did you start seeing these in
> the logs?
Sure, here's some context. This couch is part of a demo server. It travels a
lot and is cycled a lot. There is one physical server, it consists of nginx
(serving web apps and reverse proxying for couch), couchdb for persistence, and
numerous programs which read and write to couch. Traffic on couch can get very
heavy.
I didn't first see this in the logs. Some of the web apps would grind to a
halt, nginx would return 404, and then eventually couch would restart. This
would happen every couple of minutes.
> By chance do you have a scenario that reproduces this? Was this db compacted
> or replicated from elsewhere?
I wish I had a pliable scenario other than sending the server through taxi
cabs, airlines, and pulling the power cord several times a day. We haven't
seen this on any of our production servers.
This server was not subject to any replication. Most databases on it are
compacted often.
Last night we were able to drill down to one particular program which was
triggering the crash. One by one, we backed up, deleted, and rebuilt the
databases that program touched. There was one database which seemed to be the
culprit, lets call it History. History is a dumping ground for stale docs from
another db. History is almost always written to, and rarely read from. We
don't compact History since all docs in it are one revision deep. We never
replicate to or from it. The only reason we deem History the culprit is
because after rebuilding it, there hasn't been a crash for over 12 hours.
I have an additional question. Is it possible to turn couch logging off
entirely, or would redirecting to dev/null suffice? When couch would crash,
hundreds of MB of crap would get dumped to the log. (
{{badmatch,{ok,<<32,50,48,48,10 … 'hundreds of MB of crap' … ,0,3,232>>}}).
Right when this dump occurred, the cpu spiked and the server began its downward
descent.
Best
>
> Thanks,
>
> Bob
> On Aug 7, 2012, at 2:06 AM, stephen bartell <[email protected]> wrote:
>
>> Hi all, could some one help shed some light on this crash I'm having. I'm
>> on v1.2, ubuntu 11.04.
>>
>> [Mon, 06 Aug 2012 18:29:16 GMT] [error] [<0.492.0>] ** Generic server
>> <0.492.0> terminating
>> ** Last message in was {pread_iolist,88385709}
>> ** When Server state == {file,{file_descriptor,prim_file,{#Port<0.2899>,79}},
>> 93302896}
>> ** Reason for termination ==
>> ** {{badmatch,{ok,<<32,50,48,48,10 … huge dump … ,0,3,232>>}},
>> [{couch_file,read_raw_iolist_int,3},
>> {couch_file,maybe_read_more_iolist,4},
>> {couch_file,handle_call,3},
>> {gen_server,handle_msg,5},
>> {proc_lib,init_p_do_apply,3}]}
>>
>> I'm not too familiar with erlang, but what I gathered from the src was
>> `pread_iolist` function is used when reading anything from the disk. So I
>> think this might be a corrupt db problem.
>>
>> Thanks,
>> Stephen Bartell
>
