[XML-SIG] Advice on how to deal with locking problems using python-wrapped C libs in MT frameworks like Zope/Twisted?
Martin v. L÷wis
30 Mar 2003 23:26:46 +0200
Craeg K Strong <email@example.com> writes:
> When libxslt tries to resolve the relative URL, a request is going out
> to grab:
> which ends up coming back in to Zope. Zope is multi-threaded, so why
> shouldn't that be able to return successfully? Is libxslt-python somehow
> holding on to the GIL or-- maybe it is still in the middle of the "read"
> call and is therefore holding a lock on that resource?
One would have to know a lot of internal details here that you
probably have to investigate yourself, unless you can find some
Zope-and-libxslt guru. Here are some theories:
1. Zope is not responding since it considers the request incomplete
One would have to study the 88 bytes request data (use -s2000 on
strace) to determine whether the request is complete - yet Zope
may *still* waiting for more data for some reason (e.g. a bug).
2. Zope is not configured to process more than one request. It accepts
the connection only since this is in the listen backlog; it doesn't
actually read the data - not because it couldn't, but because it
does not want to.
3. The GIL is held while libxslt makes this request.
If I think long enough, I can come up with more consistent theories :-)
Which of these are plausible, I don't know; most likely, the real
reason would not give a plausible theory.
What mechanism in libxslt does make the callback? Is that Python code,
or code implemented in libxslt itself?