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From: Jyrki Pulliainen <jyrki@dywypi.org>
Date: Mon, 28 Mar 2011 16:42:19 +0300
Message-ID: <AANLkTin1BJhStx6N_oO=vs4vVXBEJrr+4v-oj+woHx-C@mail.gmail.com>
Subject: Re: Strange bug on long polling changes feed, using OS X
To: user@couchdb.apache.org
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On 28 March 2011 16:36, Matt Goodall <matt.goodall@gmail.com> wrote:
> On 28 March 2011 13:32, Jyrki Pulliainen <jyrki.pulliainen@gmail.com> wrote:
>
>> Hi,
>>
>> I've run into a strange bug with longpoll changes feed, using OS X. I
>> can not reproduce this bug on Ubuntu Linux running the same version of
>> CouchDB. This has been verified on two different OS X computers, both
>> running Snow Leopard in both, 32 bit mode and 64 bit. The other one
>> has the Couchbase version of CouchDB installed, the other one has one
>> installed via homebrew.
>>
>> Problem is following: I have my own CouchDB driver for Tornado
>> Asynchronous web framework called Trombi[1]. It's basically just a
>> wrapper around HTTP calls to CouchDB, making them play nicely with the
>> asynchronous nature of Tornado (unlike other Python CouchDB
>> libraries). I've made a test[2] that opens up longpolling changes feed
>> and writes a document in database and then waits to receive the same
>> document via changes feed listener. What happens is that the changes
>> feed listener never gets the reply or if it gets one, it is empty (ie.
>> rows: []).
>>
>> First guess was the the use of pycurl (and thus libcurl) to be the
>> problem, but after switching to pure Python SimpleHTTPClient offered
>> by Tornado the problem persisted. Next I blamed it on Tornado
>> framework, but further inspection using tcpdump and tcpflow revealed
>> that the CouchDB actually produces an erroneous reply, an empty
>> changes feed result (even though there should be at least one change).
>>
>> Has anyone bumped in to a similiar problem? I can't reproduce this on
>> command line with pycurl, only with my tests. To simply reproduce this
>> yourself, just clone Trombi[1], check out branch
>> wip/simple-httpclient-compatibility, install tornado, nosetests and
>> pycurl via pip/easy_install and make sure you have couchdb binary in
>> PATH. After this, just run nosetests -v and the tests should stall on
>> the test mentioned before[2].
>>
>
> I hit an issue on Linux so it's probably unrelated, but this sounds similar
> to a problem I recently came across with the _changes feed when using a
> filter and limit=1.
>
> It's been fixed in the 1.0.x branch but I don't think it's in an official
> release yet. See,
> https://github.com/apache/couchdb/commit/6d8f063e2d05a3edaf029b857a7af3f86bd6e8bc
> .

Yeah, the symptoms match on that one. However, I'm not sending limit,
but looking at the patch that could affect my problem too. I just have
to figure out how to compile CouchDB manually :)

- Jyrki