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ra_serf crashes on Windows with AVG 2012 Surf-Shield

From: Johan Corveleyn <jcorvel_at_gmail.com>
Date: Wed, 11 Apr 2012 01:13:36 +0200

I first noticed this during testing of 1.7.4, and now reproduced it
with trunk, both with serf 1.0.0 and 1.0.3: when running the testsuite
over serf, on Windows XP with "AVG Anti-virus Free Edition 2012" [1]
enabled, I get a lot of crashes and also a couple of infinite loops.
It's probably not a new problem since 1.7.4, but new since AVG 2012
(1.7.4 is probably the first time in 2012 that I ran the testsuite
over ra_serf).

I narrowed it down to the AVG option "Surf-Shield" (part of
"LinkScanner"). If I disable "Surf-Shield", the testsuite completes
normally over ra_serf. The other ra_* methods don't have a problem
with AVG Surf-Shield.

I don't know what Surf-Shield does. Its description says: "Can detect
exploit sites and other complex online threats". There is some more
explanation on the AVG website, but it's still pretty vague [2]. Maybe
it does some throttling of requests/responses, inspecting things or
so, ... but whatever it does, svn+serf should probably not crash or
hang. I'm guessing AVG is used by a significant percentage of
non-corporate Windows users (and Surf-Shield is enabled by default in
the Free Edition 2012). I'm not sure if the fact that the server runs
on localhost (and thus with very fast access) is part of the equation.

Here are some of the tests that crash (I don't let the entire
testsuite run to completion, because some tests really hang, and I
have to kill the svn.exe process to have the testsuite continue (which
gets tedious after a while :-))):

    authz_tests.py 4, 5, 7, 10, 15, 16
    basic_tests.py 6, 21, 31, 59
    blame_tests.py 10

These really hang (one cpu core fully occupied by svn.exe, memory
usage continuously increasing a bit (a couple of KB's per second); I
can only continue after killing the svn.exe process):

    authz_tests.py 14
    blame_tests.py 3

This one just fails, I think:

    authz_tests.py 23

Most of the crashes are similar, crashing somewhere inside
svn_ra_serf__get_mergeinfo(). But there are also a couple of others.
In attachment the dav-tests.log of all tests until I had enough of it,
and also the crash dump file of the first crash. If necessary I can
send the others too.

If there is anything I can do to provide more info, or try other
things, let me know ...

Maybe someone else on Windows can try to reproduce this, by installing
AVG Free Edition 2012? Would be interesting to know at least if it's
not a local problem for my machine, or something specific to XP ...

[1] http://www.avg.com
[2] http://www.avg.com/eu-en/linkscanner

Received on 2012-04-11 01:14:36 CEST

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