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https://issues.apache.org/jira/browse/MODPYTHON-109?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Graham Dumpleton updated MODPYTHON-109:
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Fix Version/s: (was: 3.3.1)
> Signal handler calling Py_Finalize() when child processes being killed.
> -----------------------------------------------------------------------
>
> Key: MODPYTHON-109
> URL: https://issues.apache.org/jira/browse/MODPYTHON-109
> Project: mod_python
> Issue Type: Bug
> Components: core
> Affects Versions: 3.2.7
> Reporter: Graham Dumpleton
> Assigned To: Graham Dumpleton
> Attachments: MP109_20060308_grahamd_1.diff
>
>
> When Apache is killing off child processes as part of actions taken when the
> "apachectl restart" or "apachectl graceful" command is run, it sends a
> SIGTERM signal to the child processes. This causes a signal handler
> registered by Apache to be run. That signal handler destroys the main child
> memory pool. That memory pool has though a cleanup handler associated with it
> which was registered by mod_python. That cleanup handler ultimately calls
> Py_Finalize().
> The problem with this is that Py_Finalize() isn't safe to be called from a
> signal handler and if a handler is still executing or there is a separate
> thread running in the context of Python, a deadlock will likely ensue. This
> will prevent the child process exiting due to the SIGTERM causing the Apache
> parent process to send it a SIGKILL to really kill it.
> For a more detailed assessment of the problem and what lead to this
> conclusion see:
> http://www.modpython.org/pipermail/mod_python/2006-January/019865.html
> http://www.modpython.org/pipermail/mod_python/2006-January/019866.html
> http://www.modpython.org/pipermail/mod_python/2006-January/019870.html
> To avoid the problem, the only choice seems to be avoid calling Py_Finalize()
> from the signal handler. The simplistic way of doing this seems to be to add:
> if (child_init_pool)
> return APR_SUCCESS;
> at the start of python_finalize(). This will mean that Py_Finalize() is never
> called in child processes. The full consequences of this is unknown, but on
> face value it would seem that it might be a reasonable thing to do. More
> research may be required.
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