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Date: Fri, 18 Mar 2011 17:54:16 +0000
Message-ID: <AANLkTi==dZa+SrVu=Vu+ZUfLwRLHhZBbu0P_QaRspgSo@mail.gmail.com>
Subject: Re: CouchDB exceptions
From: Filipe David Manana <fdmanana@apache.org>
To: dev@couchdb.apache.org
Cc: kowsik <kowsik@gmail.com>
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Ah,

I think the issue is while we are folding the by sequence btree, we
are not checking if the database file changed. So if compaction
finishes before finishing the btree fold, we reach that error.
I can't see right now any other situation, involving _changes, that
might cause that issue.


On Fri, Mar 18, 2011 at 5:40 PM, kowsik <kowsik@gmail.com> wrote:
> Been seeing this on our production CouchDB's (1.0.2) sporadically. We
> are using the _changes feed, background view indexing and automatic
> compaction.
>
> Uncaught error in HTTP request: {exit,
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {noproc,
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0{gen_server,call,
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 [<0.1478.0>,
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0{pread_iolist,290916},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0infinity]}}}
>
> =C2=A0Stacktrace: [{gen_server,call,3},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_file,pread_iolist,2},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_file,pread_binary,2},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_file,pread_term,2},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_db,make_doc,5},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_db,open_doc_int,3},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_db,open_doc,3},
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 {couch_changes,'-make_filter_fu=
n/4-lc$^4/1-3-',2}]
>
> Not reproducible yet, but it seems compacting while there are active
> _changes listeners seems to trigger this. After the exception the
> _changes listeners are disconnected which then connect back and
> everything goes back to normal. beam itself holds up, though last
> night it terminated with no logs, nothing. Just poof. Any ideas?
>
> Thanks,
>
> K.
> ---
> http://blitz.io
> http://twitter.com/pcapr
>


--=20
Filipe David Manana,
fdmanana@gmail.com, fdmanana@apache.org

"Reasonable men adapt themselves to the world.
=C2=A0Unreasonable men adapt the world to themselves.
=C2=A0That's why all progress depends on unreasonable men."