** Description changed: [Impact] - * An explanation of the effects of the bug on users and - - * justification for backporting the fix to the stable release. - - * In addition, it is helpful, but not required, to include an - explanation of how the upload fixes this bug. + Ruby processes can sometimes get stuck in a loop consuming 100% CPU, as + described upstream and in the debian bug report. It has most commonly + been seen in the puppet agent. [Test Case] + It's not easy to reproduce. It has been suggested that this script eventually reproduces the problem: - * detailed instructions how to reproduce the bug + while nice -n19 /opt/puppetlabs/puppet/bin/ruby sched_yield_loop.rb; do + :; done - * these should allow someone who is not familiar with the affected - package to reproduce the bug and verify that the updated package fixes - the problem. + Where sched_yield_loop.rb comes from "https://bugs.debian.org/cgi- + bin/bugreport.cgi?att=1;bug=876377;filename=sched_yield_loop.rb;msg=22" + + I personally haven't seen it happen with the script, but maybe it could + take days. [Regression Potential] - - * discussion of how regressions are most likely to manifest as a result - of this change. - - * It is assumed that any SRU candidate patch is well-tested before - upload and has a low overall risk of regression, but it's important - to make the effort to think about what ''could'' happen in the - event of a regression. - - * This both shows the SRU team that the risks have been considered, - and provides guidance to testers in regression-testing the SRU. + Races with threads can be hard to reproduce, and so can regressions. + Patch has been applied upstream and to debian for more than a year now. [Other Info] - - * Anything else you think is useful to include - * Anticipate questions from users, SRU, +1 maintenance, security teams and the Technical Board - * and address these questions in advance + Not at this time. [Original Description] Ubuntu 16.04 ruby 2.3.1-2~16.04.12 kernel 4.4.0-148-generic We've noticed an issue across multiple servers where puppet agent will seem to get stuck and consume 100% CPU for days or weeks on end until manually killed. root@ps-prod-jenkins-qa-ui02:~# ps auxwwww|grep -i puppe[t] root 1412 0.0 0.2 143716 38680 ? Ssl Jun11 0:39 /usr/bin/ruby /usr/bin/puppet agent root 34884 74.4 0.3 286848 53724 ? Rs Jun23 1141:44 puppet agent: applying configuration root 111481 94.1 0.3 288572 54996 ? Rs Jun18 8642:32 puppet agent: applying configuration root 128479 54.8 0.3 286744 53596 ? Rs 10:30 250:17 puppet agent: applying configuration Strace shows it in a sched_yield() loop: root@ps-prod-jenkins-qa-ui02:~# strace -p 34884 -c strace: Process 34884 attached ^Cstrace: Process 34884 detached % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 100.00 0.002130 0 123189 sched_yield ------ ----------- ----------- --------- --------- ---------------- 100.00 0.002130 123189 total Some googling shows this is a common issue which was supposedly fixed/backported to ruby 2.3: https://tickets.puppetlabs.com/browse/PA-1743 https://bugs.ruby-lang.org/issues/13794 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=876377 The following open Ubuntu bugs look to be having the same issue and suggest that this fix made it into Debian but never made it into Ubuntu: https://bugs.launchpad.net/ubuntu/+source/pcs/+bug/1783161 https://bugs.launchpad.net/ubuntu/+source/pcs/+bug/1772998
-- You received this bug notification because you are a member of Ubuntu Server, which is subscribed to ruby2.3 in Ubuntu. https://bugs.launchpad.net/bugs/1834072 Title: Puppet agent using 100% CPU, in sched_yield() loop. Looks like an issue with ruby2.3 which has been fixed but not yet made it into Ubuntu. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ruby2.3/+bug/1834072/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
