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From "Graham Dumpleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MODPYTHON-202) Allow mechanism used by global mutex locks to be specified.
Date Thu, 09 Nov 2006 21:05:37 GMT
    [ http://issues.apache.org/jira/browse/MODPYTHON-202?page=comments#action_12448585 ] 
            
Graham Dumpleton commented on MODPYTHON-202:
--------------------------------------------

A configuration option can possibly be modelled off how the AcceptMutex directive for Apache
works. Ie:

  http://httpd.apache.org/docs/2.2/mod/mpm_common.html#acceptmutex

Would just need to decide whether we do it as a PythonOption or introduce a new directive
instead.

Note there is an interesting comment in there about using pthread which may be relevant to
the problem you are seeing. Specifically:

  On most systems, when the pthread option is selected, if a child process terminates
  abnormally while holding the AcceptCntl mutex the server will stop responding to
  requests. When this occurs, the server will require a manual restart to recover.

  Solaris is a notable exception as it provides a mechanism, used by Apache, which
  usually allows the mutex to be recovered after a child process terminates abnormally
  while holding a mutex.

  If your system implements the pthread_mutexattr_setrobust_np() function, you may
  be able to use the pthread option safely.

> Allow mechanism used by global mutex locks to be specified.
> -----------------------------------------------------------
>
>                 Key: MODPYTHON-202
>                 URL: http://issues.apache.org/jira/browse/MODPYTHON-202
>             Project: mod_python
>          Issue Type: New Feature
>          Components: core
>    Affects Versions: 3.2.10
>            Reporter: Graham Dumpleton
>
> When using experimental Apache ITK MPM, described at:
>   http://home.samfundet.no/~sesse/mpm-itk/
> global mutex locks will fail if Apache used semaphores because requests against different
virtual hosts run as different users and user will not have permission to access the semaphore
to lock it. See:
>   http://www.modpython.org/pipermail/mod_python/2006-November/022536.html
> for original mailing list post about this from Sam Morris.
> A suggested fix of finding a specific mechanism that works rather than default used by
Apache, seems to work:
>   http://www.modpython.org/pipermail/mod_python/2006-November/022537.html
>   http://www.modpython.org/pipermail/mod_python/2006-November/022538.html
>   http://www.modpython.org/pipermail/mod_python/2006-November/022539.html
> If available MPMs with such constraints are going to appear, may make sense to have an
option to configure which allows one to override at compile time the default mechanism used
for global mutex locks so that it can be made to match what may be required for a specific
MPM that Apache is compiled to use.

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