[Twisted-Python] Moderately-long running processes timing out in Twisted

[glyph at divmod.com]

It seems that you have been a victim of at least one recently-fixed bug:

    http://twistedmatrix.com/trac/ticket/3244

and at least one long-standing one:

    http://twistedmatrix.com/trac/ticket/1753

As you can see from the tone of my (unfortunate) comment on the latter 
ticket, I don't think a lot of people use Oracle with Twisted.

However, the issue is simple to hack around temporarily: set your 
ConnectionPool's "good_sql" attribute to 'select 1 from dual' as itamar 
suggests on #1753.

Then, please submit a patch, and ideally a buildslave with a copy of 
oracle installed so that we can maintain support for it :).

On 06:06 pm, spiritualmechanic at yahoo.com wrote:
>I looked at the adbapi code and it appears the ConnectionLost exception 
>is coming from there, not from cx_Oracle. At least that's what is in 
>the error log:
>
>2008-09-05 12:25:48-0400 [HTTPChannel,9003,127.0.0.1] adbapi closing: 
>cx_Oracle
>2008-09-05 12:25:48-0400 [HTTPChannel,9003,127.0.0.1] Connection lost.
>2008-09-05 12:25:48-0400 [-] Unhandled Error
>        Traceback (most recent call last):
>          File "/opt/Python25/lib/python2.5/threading.py", line 440, in 
>run
>            self.__target(*self.__args, **self.__kwargs)
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/python/threadpool.py", line 161, in _worker
>            context.call(ctx, function, *args, **kwargs)
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/python/context.py", line 59, in callWithContext
>            return self.currentContext().callWithContext(ctx, func, 
>*args, **kw)
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/python/context.py", line 37, in callWithContext
>            return func(*args,**kw)
>        --- <exception caught here> ---
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/internet/threads.py", line 24, in _putResultInDeferred
>            result = f(*args, **kwargs)
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/enterprise/adbapi.py", line 380, in _runInteraction
>            conn.rollback()
>          File "/opt/python/lib/python2.5/site- 
>packages/twisted/enterprise/adbapi.py", line 65, in rollback
>            raise ConnectionLost()
>        twisted.enterprise.adbapi.ConnectionLost:
>
>I don't know what
>
>        --- <exception caught here> ---
>
>means. I'm guessing there's some sort of issue with Oracle but our DBA 
>didn't see anything obvious in his logs. Is there a way for me to tell 
>what exactly the "exception caught here" is?
>
>Steve
>
>
>
>----- Original Message ----
>From: L. Daniel Burr <ldanielburr at mac.com>
>To: Twisted general discussion <twisted-python at twistedmatrix.com>
>Sent: Friday, September 5, 2008 1:15:40 PM
>Subject: Re: [Twisted-Python] Moderately-long running processes timing 
>out in Twisted
>
>Hi Steve,
>
>On Fri, 05 Sep 2008 11:51:15 -0500, Steve Lewis
><spiritualmechanic at yahoo.com> wrote:
>>We're trying to use twisted as a sort of bus, a centralized place to
>>manage all of our SOA enpoints (mostly through XML-RPC). We have a few
>>services that access the Oracle DB directly (adbapi). In production
>>we're getting intermittent ConnectionLost exceptions from cx_Oracle.
>>Most of these are queries that take a couple of seconds.
>
>Hmm, it is kind of hard to say what the problem could be, without
>seeing the code that is using adbapi and cx_Oracle.
>
>When you say you are receiving ConnectionLost exceptions from 
>cx_Oracle,
>are they *really* from cx_Oracle, i.e., "ORA-03135 - Connection 
>lost...",
>or are they just the result of adbapi calling its connectionLost 
>method?
>>Has anyone seen this kind of behavior before? What we're probably 
>>going
>>to do in the short term is just remove twisted from the equation for
>>these methods that seem to be timing out. But we're relatively new to
>>twisted and I wonder if we're doing something that's obviously wrong.
>
>I've used cx_Oracle with twisted many times, with many different 
>workloads,
>including stored procedures with OUT parameters, and it has always 
>worked
>as expected.  If you are able to provide some code, this list might be
>able to provide you with more prescriptive advice.
>
>Hope this helps,
>
>L. Daniel Burr
>
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