[Twisted-Python] Twisted and Thread, thread not running when twisted app is running as service

[Sereysethy TOUCH]

I am on MacOS, it is a development phase, but deployment will be on Linux.

It is hard to run dtrace/dtruss on MacOS due to the "system integrity
protection" on MacOS. I got some output but very limited information.

So if there is a workaround you might suggest?

TS

On Thu, May 21, 2020 at 10:20 PM Jean-Paul Calderone <
exarkun at twistedmatrix.com> wrote:

> On Thu, May 21, 2020 at 3:56 PM Sereysethy TOUCH <
> touch.sereysethy at gmail.com> wrote:
>
>> Hi Jean-Paul,
>>
>> I found the error after working on a short, self contained, correcte
>> example. It is not about twisted and normal thread in general, but
>> something else.
>>
>> After more tests, I come to realise that whenever I instantiate this
>> class PolicyClient from this library
>> https://github.com/ray-project/ray/blob/master/rllib/env/policy_client.py in
>> my protocol or just anywhere, twisted app either freezes or terminates, and
>> this *only* happens when the app runs as a daemon, created using a
>> service (.tac file).
>>
>> I hope you can take a look at the class PolicyClient, why it causes
>> problem to reactor main loop. Please point me to where the idea might come
>> from.
>>
>> I can give you the example but not sure if it is enough, as the client
>> needs to connect to a server.
>>
>
> It looks like PolicyClient does a blocking HTTP request in __init__.
> Since PolicyClient is instantiated in the reactor thread, this will block
> the reactor.  Perhaps this call is hanging for some reason when the process
> has daemonized?  This would be unusual but not unheard of.  For example,
> there are macOS environments where a process does not have access to the
> network if it is not associated with a windowing session.
>
> What platform do you observe the problem on, and what more can you learn
> about what the process does on its way to hanging (eg can you run strace on
> it)?
>
> Jean-Paul
>
>
>>
>> Thank you,
>> TS
>>
>>
>> On Thu, May 21, 2020 at 5:23 PM Jean-Paul Calderone <
>> exarkun at twistedmatrix.com> wrote:
>>
>>> On Thu, May 21, 2020 at 10:58 AM Sereysethy TOUCH <
>>> touch.sereysethy at gmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> I am developing a twisted app, and it runs as a service using twistd -y
>>>> to start the app.
>>>> I am having a problem of running a thread. I know it is not recommended
>>>> to use thread, but the library that I use, the object created is running in
>>>> a thread.
>>>>
>>>> Here is the problem:
>>>>
>>>> 1) if I start reactor by running reactor.run() directly, thread is
>>>> running fine
>>>> 2) if I run it as a service using twisted, the thread is not running,
>>>> it runs but it seems to be blocked, because I tried to write something to
>>>> file using time.sleep(), but file is empty.
>>>>
>>>> Is there something that I miss? How can I debug this?
>>>>
>>>
>>> A good next step would be to create at Short, Self Contained, Correct
>>> (Compilable), Example <http://sscce.org/> and share it.
>>>
>>> Jean-Paul
>>>
>>>
>>>>
>>>> Thank you,
>>>>
>>>> TS
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