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From Adam Kocoloski <kocol...@apache.org>
Subject Re: gen_server timeout
Date Wed, 20 Oct 2010 15:14:40 GMT
On Oct 18, 2010, at 2:33 AM, Alex Koshelev wrote:

> Hi, all!
> 
> We at Yandex create the new project and use CouchDB as our primary storage.
> We live in the python universe so use python as client-code language and for
> view-server. There is number of ready python libraries for CouchDB and we
> have chosen -- couchdb-python (http://code.google.com/p/couchdb-python/).
> 
> CouchDB is hosted on Ubuntu 10.04 boxes (64bit; 16 Cores; 23GB RAM) with
> master + 2 slaves setup. And databases from number of megabytes to some
> gigabytes in size.
> 
> We faced some strange CouchDB behavior which is related to our view-server
> and its integration with storage (I think). We get `timeout` errors from the
> storage. This errors appear even when trying to issue a replication, getting
> database information (/db/_info) or querying views itself.
> 
> Here is some logs with error messages -- http://dpaste.com/hold/258268/ .
> View-server works fine and has no error messages. But, we've noticed that it
> is getting some strange `reduce` requests with empty arguments.

I've noticed this on occasion with some view files which do not get closed properly.  The
system starts scanning backwards from the end of the file in 4k increments looking for a valid
header, and if the scan takes longer than 5 seconds you get this error report.

You wouldn't see this exect error report on a DB info request (GET /db) or a replication,
although you could see it on a view group info request (GET /db/_design/dname/_info).

> Our local.ini has `os_process_tmeout` preset with 6000000 (six million
> milliseconds) and it doesn't help. It seams that this timeout doesn't event
> count and response with `timeout` error returns in some seconds (over 5 I
> think).

Yep, that makes sense the os_process_timeout doesn't take effect here.  This is most likely
an issue opening the .view file.

If you feel like doing some mucking around you can try chopping off the end of the .view file
in question and seeing if the system is able to open it more easily.  ~1 MB should be enough.
 You'll need to reindex a few documents, but it beats rebuilding the whole index (which afaik
is really the only other alternative at this point).  Regards,

Adam

> The same issue we've encountered earlier with Ubuntu 8.04 (Hardy) and
> previous version (pre 1.0) of CouchDB.
> 
> What do you think about that? Where is our mistake or misconfiguration?
> 
> Thanks!
> 
> ---
> Alexander Koshelev


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