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From Ryan Bloom <...@covalent.net>
Subject Re: [Fwd: [Patch]: Scoreboard as linked list.]
Date Fri, 03 Aug 2001 18:10:26 GMT

> I have other concerns that I still haven't finished thinking through, so I
> haven't posted them yet, but I will continue to analyse the patch and post
> comments as I finish thinking them through.

As promised, the other concerns:

1)  We are allocating and destroying shared memory segments.  If I have a module that
creates an other_child, not an Apache child process, that module has access to the
scoreboard in the other_child process.  If we start to create and delete segments of shared
memory that the module has access to, then we are asking for a seg-fault.  If we are willing
to require modules to restart the other_child process whenever Apache restarts, then we can
avoid this problem, but this is a VERY large penalty.

2)  I may be wrong, but I believe we have a race-condition.  find_child_by_pid walks the
scoreboard without locking it.  Since we call that function from the parent whenever a child
process dies, this looks like a chance for a seg fault, but I am still trying to figure out
what I
am missing.  Rather than continue to look for my misunderstanding, can somebody explain it
to me?

That's it for now.  But I'm not done reviewing the code yet.  :-)

Ryan

_____________________________________________________________________________
Ryan Bloom                        	rbb@apache.org
Covalent Technologies			rbb@covalent.net
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