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<p>Hello,</p>
<br>
<div class="moz-cite-prefix">On 27.04.17 04:18, Cody Herzog wrote:<br>
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<p class="MsoNormal">Hello.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'm running Kamailio 4.3.5 on Ubuntu Server
14.04.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I just started using the app_python module
together with the OpenTok Python SDK, described here:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="https://tokbox.com/developer/sdks/python/">https://tokbox.com/developer/sdks/python/</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My basic Python test script works fine, but
when I add an import statement in the Python script to bring
in a package from the OpenTok Python SDK, Kamailio terminates
right after launch with the following log message:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">"terminating due to SIGCHLD"<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was surprised to not find any extra log
messages indicating which child process was causing the
signal.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I hacked the code in the handle_sigs()
function in main.c.c to NOT terminate in response to SIGCHLD,
and was surprised to see that my Python script was working
fine, and was able to properly use the OpenTok Python SDK.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I then started adding more debugging log
statements and discovered that the call to waitpid() was
returning 0, which apparently indicates that no child process
has changed state.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It's very strange, because it seems that
SIGCHLD is being sent and handled, but waitpid() is indicating
that no child process has changed state.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'm not sure if that is valid situation
which needs to be handled. Perhaps SIGCHLD is sometimes sent
for spurious or harmless reasons which should be ignored, and
not result in total Kamailio termination.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My current workaround is to NOT terminate
when SIGCHLD is received and waitpid() indicates that no child
process has changed state. In other words, I only terminate
when the waitpid() while() loop has been entered at least once
due to a return value greater than 0.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Does that seem like a change that might
make sense in the master branch going forward, or does it seem
dangerous somehow?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'm not sure if this is helpful, but the
waitid() system call (available since Linux 2.6.9) provides
more precise control over which child state changes to wait
for.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://manpages.ubuntu.com/manpages/trusty/man2/wait.2.html">http://manpages.ubuntu.com/manpages/trusty/man2/wait.2.html</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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</blockquote>
this can happen because your python script (or the libs used there)
creates new processes and they terminate. Kamailio has a strict
policy on watching the children and terminating if one disappears.<br>
<br>
I think we can relax that based on your suggestion. Can you make a
pull request on github.com/kamailio/kamailio with your proposed
changes?<br>
<br>
Ideally with a new parameter to control this behaviour, but don't
worry if it is not straightforward for you to look at flex/bison
files, I will do it on top of your patch.<br>
<br>
Cheers,<br>
Daniel<br>
<br>
<pre class="moz-signature" cols="72">--
Daniel-Constantin Mierla
<a class="moz-txt-link-abbreviated" href="http://www.twitter.com/miconda">www.twitter.com/miconda</a> -- <a class="moz-txt-link-abbreviated" href="http://www.linkedin.com/in/miconda">www.linkedin.com/in/miconda</a>
Kamailio Advanced Training - May 22-24 (USA) - <a class="moz-txt-link-abbreviated" href="http://www.asipto.com">www.asipto.com</a>
Kamailio World Conference - May 8-10, 2017 - <a class="moz-txt-link-abbreviated" href="http://www.kamailioworld.com">www.kamailioworld.com</a></pre>
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