[pyOpenSSL] pyOpenSSL threading issues under Linux

[Dan Williams]

Hi,

I'm using pyOpenSSL for the Fedora Extras build system after discovering
that m2crypto was (1) less stable and (2) more complicated.  The stuff
I've been developing is available here, and implements XMLRPC server +
client and HTTP server + client with two-way client server certificate
verification.

http://cvs.fedora.redhat.com/viewcvs/extras-buildsys/?root=fedora

Interesting stuff is probably in the 'common' directory, including
AuthedXMLRPCServer.py, XMLRPCServerProxy.py, HTTPServer.py, and
HTTPSURLOpener.py.  It's inspired by, in part, pyOpenSSL examples,
m2crypto's workarounds, RHN/up2date usage of pyOpenSSL, and some other
random stuff.  It does mostly work, feel free to look it over for bugs
or as examples.

So on the problem...  Both the XMLRPC server/client and the HTTPS
server/client have tests built in that make heavy use of threads.  The
pyOpenSSL package in Fedora Core is _not_ built with OpenSSL thread
safety, the patch is attached to this email.

However, even with that patch, python falls over fairly quickly on
multi-cpu boxes with segfaults, while single-cpu boxes work 90% of the
time and segfault after a while.  Turning off SSL in the testcases
results in success.  Debug builds of python fail fairly quickly using
SSL under test cases with this message:

Fatal Python error: UNREF invalid object
Abort

So I've thought of a number of things here:

1) The pyOpenSSL locking patch I've applied isn't working correctly, or
I've forgotten some bits
2) Maybe we need to grab python locks in the pyOpenSSL locking patch in
addition to the local pthreads lock
3) Perhaps pyOpenSSL needs to lock calls into OpenSSL with python locks
too
4) Incorrect reference counting in pyOpenSSL?
5) Incorrect reference counting in python itself?

I'd be very grateful if anyone has tips on how to debug this sort of
thing, or has insights/ideas about threading, python, OpenSSL, and
pyOpenSSL.  I'd be happy to provide more condensed testcases than just
the CVSweb link above, if that would help.

Thanks!
Dan


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