Issue #5306 has been updated by Charlie Savage. Unfortunately it is not. That was the first problem - and resulted in segmentation faults. We manually backported the fix for #5299 to our local copy of ruby 193. Once we did that, it fixed the segmentation faults, but resulted in this problem. So this is a new problem with that particular commit. ---------------------------------------- Bug #5306: Application Hangs Due to Recent rb_thread_select Changes http://redmine.ruby-lang.org/issues/5306 Author: Charlie Savage Status: Open Priority: High Assignee: Category: core Target version: 1.9.3 ruby -v: ruby 1.9.3dev (2011-09-09 revision 33236) [x86_64-linux] This commit: 4e9438bc9153f7a1f4ea0af85c8dbe359e1a55d8 Changed the implementation of rb_thread_select. It causes eventmachine to hang on CentOS 5.5. Not sure what the issue is, but its easily reproduced by by running the test eventmachine/tests/test_epoll.rb. We noticed this because it also causes the tweetstream gem to hang. The same setup works on Fedora 14 and an up-to-date arch linux. Specific version information included below. We temporarily fixed this by reverting the commit. Since Centos is a common production environment (and the one we are using), this seems to us a blocker for 1.9.3. We are happy to provide any additional information or test fixes. Thanks - Charlie -------------- We are running this version of CentOS: Linux app1.zerista.com 2.6.18-238.19.1.el5.centos.plus #1 SMP Mon Jul 18 10:05:09 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux And this version of Fedora: Linux ammonite.internal.zerista.com 2.6.35.14-95.fc14.x86_64 #1 SMP Tue Aug 16 21:01:58 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux And this version of eventmachine: eventmachine (1.0.0.beta.3) And this version of tweetstream: tweetstream (1.0.4) -- http://redmine.ruby-lang.org