[omniORB-dev] Re: [omniORB] omniORBpy deadlock / termination problem.

[Duncan Grisby]

On Monday 13 October, Harri Pasanen wrote:

I've only just had a chance to look at this...

> 1. A shutdown method that is registered with Python's atexit module.  
> This is required to properly close pyThreadCache, which needs to run 
> Python code, so python still needs to be present.   Otherwise it can 
> be that  when pyThreadCache is destructed at omniORB cleanup during  
> process exit, the python interpreter has already gone.

How can that happen?  The thread cache is only destroyed if
orb->destroy() is called. As long as that is called before process
exit time, I don't think there can be a problem. Can you explain a
situation where it is an issue?

Also, the atexit module was added in Python 2.0. omniORB needs to
support Python 1.5.2, so it can't be a general solution.

> 2. pyThreadCache join needs to be in python's ALLOW_THREADS macros, 
> otherwise pyThreadCache cannot be shut down from a python method.  
> (And the previous atexit change should ensure it is always called 
> from a python method).

The thread cache is killed as part of orb->destroy(). The caller of
orb->destroy() should not be holding the Python interpreter lock.

> 3. pyThreadCache table mutex was split from thread kill mutex to 
> optimize the thread killing, the former mutex being too long lived.

I don't understand that. Can you explain?

I'm afraid I still don't understand the problem. As far as I can see,
the problem you sent me is just that you are calling orb->destroy()
from a thread that is holding the Python interpreter lock.

Cheers,

Duncan.

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