Public bug reported: This is Apache2 bug 53555 (https://bz.apache.org/bugzilla/show_bug.cgi?id=53555). It was fixed in 2.4.25 but on Ubuntu Xenial, Apache2 runs with 2.4.18 and the fix was not backported yet.
This particular Apache2 setup runs with event mpm and is used as reverse proxy in front of a Tomcat (but that's irrelevant I guess). A daily log rotation happens on the Apache2 logs, causing an Apache2 reload (graceful restart). A check of apache-status each day confirms Apache bug 53555. February 4th: Current Time: Tuesday, 04-Feb-2020 17:19:28 CET Restart Time: Monday, 03-Feb-2020 09:20:48 CET Parent Server Config. Generation: 2 Parent Server MPM Generation: 1 Server uptime: 1 day 7 hours 58 minutes 39 seconds Server load: 0.00 0.00 0.00 Total accesses: 59027 - Total Traffic: 1.7 GB CPU Usage: u175.56 s424.83 cu0 cs0 - .522% CPU load .513 requests/sec - 15.7 kB/second - 30.6 kB/request 1 requests currently being processed, 49 idle workers PID Connections Threads Async connections total accepting busy idle writing keep-alive closing 31339 1 no 0 0 0 0 0 31340 1 no 0 0 0 0 0 21534 0 yes 0 25 0 0 0 21535 0 yes 1 24 0 0 0 Sum 2 1 49 0 0 0 GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG______________ __________________________________W_............................ ...................... A couple of days later, February 7th: Current Time: Friday, 07-Feb-2020 14:06:52 CET Restart Time: Monday, 03-Feb-2020 09:20:48 CET Parent Server Config. Generation: 5 Parent Server MPM Generation: 4 Server uptime: 4 days 4 hours 46 minutes 3 seconds Server load: 0.00 0.00 0.00 Total accesses: 152913 - Total Traffic: 20.9 GB CPU Usage: u520.6 s1424.31 cu0 cs0 - .536% CPU load .422 requests/sec - 60.5 kB/second - 143.5 kB/request 1 requests currently being processed, 24 idle workers PID Connections Threads Async connections total accepting busy idle writing keep-alive closing 31339 1 no 0 0 0 0 0 31340 1 no 0 0 0 0 0 11925 0 yes 1 24 0 0 0 21535 1 no 0 0 0 0 0 4156 1 no 0 0 0 0 0 29454 1 no 0 0 0 0 0 Sum 5 1 24 0 0 0 GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG______W_______ ___________GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGG On February 8th, the remaining open slots were fully used and HTTP didn't respond anymore. Error logs filling up with the following message: "[mpm_event:error] [pid 5587:tid 139748587677568] AH00485: scoreboard is full, not at MaxRequestWorkers" Solution a) Update package to a newer upstream version for xenial-updates Solution b) Backport the fix from Apache bug 53555 ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: apache2 2.4.18-2ubuntu3.1 ProcVersionSignature: Ubuntu 4.4.0-75.96-generic 4.4.59 Uname: Linux 4.4.0-75-generic x86_64 Apache2ConfdDirListing: False ApportVersion: 2.20.1-0ubuntu2.5 Architecture: amd64 Date: Fri Feb 14 07:43:55 2020 InstallationDate: Installed on 2017-01-26 (1113 days ago) InstallationMedia: Ubuntu-Server 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.3) ProcEnviron: LANGUAGE=en_US:en TERM=xterm PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: apache2 UpgradeStatus: No upgrade log present (probably fresh install) error.log: [Fri Feb 14 06:25:06.928096 2020] [ssl:warn] [pid 27506:tid 140172129879936] AH01909: mcp-somcwc01-p.nzzmg.local:443:0 server certificate does NOT include an ID which matches the server name [Fri Feb 14 06:25:06.930524 2020] [mpm_event:notice] [pid 27506:tid 140172129879936] AH00489: Apache/2.4.18 (Ubuntu) mod_jk/1.2.41 OpenSSL/1.0.2g configured -- resuming normal operations [Fri Feb 14 06:25:06.930532 2020] [core:notice] [pid 27506:tid 140172129879936] AH00094: Command line: '/usr/sbin/apache2' modified.conffile..etc.apache2.sites-available.000-default.conf: [modified] modified.conffile..etc.apache2.sites-available.default-ssl.conf: [modified] mtime.conffile..etc.apache2.sites-available.000-default.conf: 2017-02-14T07:38:24.570441 mtime.conffile..etc.apache2.sites-available.default-ssl.conf: 2018-04-09T15:47:05.141386 ** Affects: apache2 (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug xenial -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1863210 Title: apache2 event mpm: keeps hanging in gracefully finishing when reloading (logrotate) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/1863210/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs