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<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Overall, I think trying to use threads, even “Python threads” across multiple processes is a bad idea. Threads are usually meant to
live inside one process.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Robert Mundkowsky<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Mundkowsky, Robert
<br>
<b>Sent:</b> Tuesday, April 25, 2017 1:26 PM<br>
<b>To:</b> 'Maxim Sobolev' <sobomax@sippysoft.com><br>
<b>Cc:</b> OpenSIPS devel mailling list <devel@lists.opensips.org>; Bogdan-Andrei Iancu <bogdan@opensips.org><br>
<b>Subject:</b> RE: [OpenSIPS-Users] python module - bug and questions<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks for responding. Thought you would just advise me to use specific compiler flags first.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Do you want me to use your jig (testing setup) to make a crash?
<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Or do you want me to add python code to your git repo so you can run it using your jig?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">What you are doing with code is pretty complex for me and makes my brain want to explode.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">My understanding is:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">1)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Python threads are not real threads, instead only one python thread runs at a time (per the global interpreter lock)<o:p></o:p></span></p>
<p class="MsoListParagraph"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">2)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">You are creating a Python thread (that uses one Python interpreter) in the main openSIPS process that likely loads the openSIPS user’s Python module
to be used<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">3)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Then, I assume, openSIPS main process forks children processes<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo2">
<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I assume Python thread and interpreter is treated as data and code that is copied to all children processes. Note if it were a real Linux thread then
it would not be copied to children processes.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo2">
<![if !supportLists]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><span style="mso-list:Ignore">b.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">You then use the copied Python thread in all children processes as if it is a single Python thread across the main and child processes or as if it were
a single Python thread per each main or child process<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I guess this might work, because if the Python thread is truly copied then you really have a different Python thread and interpreter per main and child processes.
But Python documentation (</span><a href="https://docs.python.org/2/c-api/init.html#c.PyThreadState"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">https://docs.python.org/2/c-api/init.html#c.PyThreadState</span></a><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">)
states “When extending or embedding Python, there is no way to inform Python of additional (non-Python) locks that need to be acquired before or reset after a fork”, which makes me think what you are doing will not work. This is because any Python modules
someone might use (e.g. MySQLdb) might use a lock in the main process that can’t get cleared in the child process.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Might be wiser to just start one Python thread and interpreter in each child process I assume is kicked off via child_init. Then you would still have the module
loaded once per child. Although I am not sure if main process needs a Python thread, but probably not.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Robert Mundkowsky<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Maxim Sobolev [<a href="mailto:sobomax@sippysoft.com">mailto:sobomax@sippysoft.com</a>]
<br>
<b>Sent:</b> Monday, April 24, 2017 10:09 PM<br>
<b>To:</b> Mundkowsky, Robert <<a href="mailto:rmundkowsky@ets.org">rmundkowsky@ets.org</a>><br>
<b>Cc:</b> OpenSIPS devel mailling list <<a href="mailto:devel@lists.opensips.org">devel@lists.opensips.org</a>>; Bogdan-Andrei Iancu <<a href="mailto:bogdan@opensips.org">bogdan@opensips.org</a>><br>
<b>Subject:</b> RE: [OpenSIPS-Users] python module - bug and questions<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Robert sorry for the delay. What could be useful if you can produce chunk of python routing code (could be NOP on the functional side) that crashes repeatedly on our voiptest jig (<a href="https://github.com/sippy/voiptests">https://github.com/sippy/voiptests</a>).
The travis is setup to build pull requests, so that you can inject your code and let it rip. It uses similar configiration of linux / python. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-Max<o:p></o:p></p>
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