Some feedback: I've installed Zope 2.1.6 from source on the same machine, with as close to an identical setup as is possible on a live server. Even after really hammering 2.1.6, though, I've been unable to produce the same hanging behaviour observed in 2.1.3. The only differences, apart from the apache rewrite rules, are that the 2.1.6 install is using GenericUserFolder 1.2.2 (vs. 1.1.0) and SiteAccess 1.0.1 (vs. 1.0.0). I doubt that these products are the cause of the problem. It's also pretty unlikely that this is an OS threads problem, at least on our platform. We're running Zope on FreeBSD with pthreads; this is a different thread implementation to that used on Linux. If this is happening on Linux, FreeBSD and Solaris, the my hunch (dare I voice it?) is that this hanging occurs somewhere deep in the bowels of ZServer. Zope has in the past been fairly stable using four threads; it was only when the threads were increased to 20 that it began hanging repeatedly. We really *do* need to run Zope with a modest number of threads, as some database queries can be expected to take a couple of seconds to complete. I really do want to get the the root of this problem; if anyone out there has some suggestions or further information requirements, I'm listening! Many thanks, -- Marcus -----Original Message----- From: Marcus Collins [mailto:mcollins@sunesi.com] Sent: 10 April 2000 14:48 To: 'zope@zope.org' Subject: [Zope] Zope hanging (poss. threads-related) Apologies for the imposing subject line... Briefly, since increasing the NUMBER_OF_THREADS that Zope uses from the default (4) to 20, Zope has been hanging randomly. A request will be sent off to Zope (whether through apache with mod_pcgi, or directly through ZServer), but the request is never served up, and Z2.log shows no record of it. No additional CPU is taken by the python process. Environment: Zope 2.1.3 (source release) python 1.5.2 GCC 2.7.2.3 FreeBSD 3.3-RELEASE The problem was reproducible on pages with framesets, where some of the frame documents are loaded, and one is omitted. It occurs when viewing the management interface, for example (manage_main is displayed, but manage_workspace is not). It seems that only one thread hangs, since other requests continue to be served. Not only frameset pages were affected, though only on frameset pages did the hanging consistently occur. This behaviour was exhibited under minimal load (one or two users), and ceased when I reverted to 4 threads and restarted Zope. Our development machine, running 2.1.4 source, had no such problems when running Zope with 20 threads. I don't recall any drastic changes or checkins between 2.1.3 and 2.1.4, though... (that was basically the /REQUEST traversal security fix) I'll be installing Zope 2.1.6, and try to approximate the the same conditions, but since this is a live machine, it's going to be tricky to find a window of time to perform the switch-over... Anyone out there with some ideas as to the root cause of these hangings, or with similar tales to tell? TIA, -- Marcus