Subj : Re: Freeing data structures in a threaded application
To   : comp.programming.threads
From : Luke  Ehresman
Date : Wed Feb 16 2005 07:24 am

David,

I think I've come up with a solution.  The full problem is that I could
have references to the session in three threads (session manager, cache
manager, and the connection handler).  When a user connects, the
connectio handler attaches to that user's session.  Connections come
and go very frequently, but the session is the persistance between
connections (much the same way that sessions work in PHP or JSP).
Currently I did not lock the session for the whole duration of the
connection, but only for individual operations within the connection.
I think that if I lock the session when a connection begins, and unlock
it right after the connection ends, this will be a better way of
handling it.  That way there is no threat of the session being deleted
while a connection still has a reference to it.

This will work because two connections cannot access the same session.
I originally was trying to avoid this because the connection could hold
the lock on the session for several seconds, and nothing else would be
able to operate on it.  But really, the only time I want the cache
manager to operate on the session is when there is no connection
attached to it.

Then I will also use the method you proposed to protect the cache
manager thread from operating on a freed session.

Thanks for helping me clear my thoughts on the issue.  I'm not new to
threaded programming, but have never written an application that uses
threads so intensively before.

Luke

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