[COUCHDB-1093] Exceptions related to _changes + compact

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.2
• Fix Version/s: 1.0.3, 1.1, 1.2
• Component/s: Database Core
• Labels: exception

Environment

I don't believe this is OS and/or hardware elated, but I'm running on a redhat 32-bit linux kernel

• Skill Level: Dont Know
• Assignee: Filipe David Borba Manana
• Reporter: kowsik
• Created: 18/Mar/11 21:15
• Updated: 07/Apr/12 22:12
• Resolved: 27/Mar/11 19:22

Description

From the last thread on the dev mailing list:

On Fri, Mar 18, 2011 at 10:54 AM, Filipe David Manana <[e-mail]> wrote:
> 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 <[e-mail]> 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,
>>                                 {noproc,
>>                                  {gen_server,call,
>>                                   [<0.1478.0>,
>>                                    

{pread_iolist,290916}

,
>>                                    infinity]}}}
>>
>>  Stacktrace: [

{gen_server,call,3}

,
>>            

{couch_file,pread_iolist,2}

,
>>            

{couch_file,pread_binary,2}

,
>>            

{couch_file,pread_term,2}

,
>>            

{couch_db,make_doc,5}

,
>>            

{couch_db,open_doc_int,3}

,
>>            

{couch_db,open_doc,3}

,
>>            

{couch_changes,'-make_filter_fun/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