[Twisted-Python] Strategy for finding source of unhandled error in Deferred

[Jean-Paul Calderone]

On Sun, Mar 18, 2018 at 11:21 AM, Jean-Paul Calderone <
exarkun at twistedmatrix.com> wrote:

> On Sun, Mar 18, 2018 at 11:04 AM, Alex Railean <ralienpp at gmail.com> wrote:
>
>> Hello,
>>
>> I have inherited a misbehaving system and am trying to troubleshoot it.
>> The code
>> is not documented and I cannot produce a minimal working example that
>> illustrates
>> the problem yet, as I don't know which parts are involved and how they
>> relate.
>>
> This produces the following entries in the log:
>> Unhandled error in Deferred:
>> CRITICAL _legacy       twcore Unhandled error in Deferred:
>>
>> Traceback (most recent call last):
>> Failure: __builtin__.type: <class 'twisted.internet.error.TimeoutError'>
>> CRITICAL _legacy       twcore
>>
>>
>>
>> How can I get more clues about what is going on? I was expecting a line
>> number,
>> or a complete call-stack.
>>
>
Try this:

    from twisted.internet.defer import setDebugging
    setDebugging(True)

This gives you creation and callback stacks in the logs.

Jean-Paul


>
>>
>> What are the recommended troubleshooting steps for finding the Deferred
>> in which
>> the error occurred?  There are are around 30 of them throughout the code,
>> is
>> there a heuristic I can use to narrow down the list of suspects?
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>
>
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