[ http://issues.apache.org/jira/browse/MODPYTHON-109?page=all ]
Work on MODPYTHON-109 stopped by Graham Dumpleton > Signal handler calling Py_Finalize() when child processes being killed. > ----------------------------------------------------------------------- > > Key: MODPYTHON-109 > URL: http://issues.apache.org/jira/browse/MODPYTHON-109 > Project: mod_python > Type: Bug > Components: core > Versions: 3.2.7 > Reporter: Graham Dumpleton > Assignee: 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. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
