[asterisk-users] Simplest way of executing a non-blocking (async) python AGI script?

[Marcelo Terres]

Take a look on that:

https://issues.asterisk.org/jira/browse/ASTERISK-20532

Regards,
Marcelo H. Terres <mhterres at gmail.com>
IM: mhterres at jabber.mundoopensource.com.br
https://www.mundoopensource.com.br
https://twitter.com/mhterres
https://linkedin.com/in/marceloterres


On 30 June 2017 at 22:23, Jonathan H <lardconcepts at gmail.com> wrote:
> OK, I give up and come grovelling, "Fork" was suggested at 18:23, it's
> now 22:20 and I have been through 4 different methods, all block with
> a 2 second delay before returning to dialplan.
>
> Here are just some of the examples I have tried, as as per the
> suggestions, I am closing all possible outputs in the forked process.
>
> https://docs.python.org/3.5/library/multiprocessing.html
> https://docs.python.org/3.5/library/multiprocessing.html?highlight=multiprocessing#multiprocessing.Process.join
> https://stackoverflow.com/questions/19747371/python-exit-commands-why-so-many-and-when-should-each-be-used
> https://stackoverflow.com/questions/27624850/launch-a-completely-independent-process
> https://stackoverflow.com/questions/13612434/why-are-the-methods-sys-exit-exit-raise-systemexit-not-working
> https://stackoverflow.com/questions/43280947/os-fork-share-local-variable-with-parent
> https://stackoverflow.com/questions/24052217/may-someone-explain-the-following-os-fork-example-to-me
> http://www.python-course.eu/forking.php
> https://pymotw.com/3/subprocess/
> http://code.activestate.com/recipes/186101-really-closing-stdin-stdout-stderr/
>
> This is the most likely looking code based on the examples. I would
> really, really appreciate a couple of pointers as to where I might be
> going wrong:
>
> #! /usr/bin/env python3
> # -*- coding: utf-8 -*-
>
> import multiprocessing as mp
> import time
> import sys
> import os
>
> #from asterisk.agi import AGI
> #agi = AGI()
>
> def f(name):
>     sys.stdin.close()
>     sys.stdout.close()
>     sys.stderr.close()
>     os.close(0)   # close C's stdin stream
>     os.close(1)   # close C's stdout stream
>     os.close(2)   # close C's stderr stream
>     time.sleep(2)
>     f = open('/var/lib/asterisk/agi-bin/tns/testing/testout.txt', 'w')
>     f.write(name)
>     f.close()
>
>
> if __name__ == '__main__':
>     print('before process')
>     mp.set_start_method('fork')
>     q = mp.Queue()
>     p = mp.Process(target=f, args=('asterisk',))
>     p.start()
>     sys.exit()
>
> On 30 June 2017 at 19:59, J Montoya or A J Stiles
> <asterisk_list at earthshod.co.uk> wrote:
>> On Friday 30 Jun 2017, Jonathan H wrote:
>>> What's the simplest, easiest quickest least-code way of firing off an AGI
>>> with some variable, and then returning to the dialplan?
>>
>> You have to use the "fork" command.  This starts a copy of the process with
>> all the same internal state including variables and filehandles.  The command
>> returns a non-zero value  (which is the PID of the child process; you may need
>> this, if you plan to outlive your children and have to clear their entries
>> from the process table)  to the parent process, and zero to the child process.
>> So in the parent, you exit and return to the dialplan; and in the child, you
>> close STDIN, STDOUT and STDERR  (so no process is waiting for you to produce
>> output),  then just take your time doing what you have to.  The parent is
>> already long dead by this time, so exiting goes nowhere.
>>
>>> I've seen people talking about fastAGI, stasis, python ASYNC... all seems
>>> rather complicated. I feel I must be missing something embarrassingly
>>> obvious - isn't there just the equivalent of the unix shell's "&"?!
>>
>> Yes, fork!  That is what the "&" operator is using "under the bonnet".
>>
>> --
>> JKLM
>>
>> Note:  Originating address only accepts e-mail from list!  If replying off-
>> list, change address to asterisk1list at earthshod dot co dot uk .
>>
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>
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