Public bug reported: OS: Ubuntu 14.04 LTS
Kernel: 3.13.0-79-generic x86_64 Apache: 2.4.7-1ubuntu4.5 In the default Apache 2.4 config on Ubuntu 14.04 LTS is the following set in /etc/apache2/apache2.conf: Mutex file:${APACHE_LOCK_DIR} default (/debian/config-dir/apache2.conf in http://archive.ubuntu.com/ubuntu/pool/main/a/apache2/apache2_2.4.7-1ubuntu4.5.debian.tar.gz) which leads to the following output of "apache2ctl -t -D DUMP_RUN_CFG": Mutex default: dir="/var/lock/apache2" mechanism=fcntl This leads constantly to a lot of these warning/emergency messages on a server with 200 busy worker threads, 100 Requests/s, 300 KB/s: [Tue Mar 08 16:08:18.596653 2016] [ssl:warn] [pid 8339:tid 140182179256064] (35)Resource deadlock avoided: AH02026: Failed to acquire SSL session cache lock [Wed Mar 09 07:09:31.099331 2016] [mpm_worker:emerg] [pid 26526:tid 139668485949184] (35)Resource deadlock avoided: AH00273: apr_proc_mutex_lock failed. Attempting to shutdown process gracefully. Solution (as suggested by Yann Ylavic from Apache): Commenting (removing) the Mutex directive, which leads to the following output of "apache2ctl -t -D DUMP_RUN_CFG": Mutex default: dir="/var/run/apache2/" mechanism=default Then, there are no error messages anymore. For the discussion, see the corresponding Apache httpd-users mailing list thread: http://httpd.markmail.org/message/c7w5aujfmy2kfazi (thread subject 'Lots of messages "[ssl:warn] Resource deadlock avoided: AH02026: Failed to acquire SSL session cache lock"' from 2016-03-08) Here some more information: # apache2ctl -V Server version: Apache/2.4.7 (Ubuntu) Server built: Jul 24 2015 17:25:11 Server's Module Magic Number: 20120211:27 Server loaded: APR 1.5.1-dev, APR-UTIL 1.5.3 Compiled using: APR 1.5.1-dev, APR-UTIL 1.5.3 Architecture: 64-bit Server MPM: worker threaded: yes (fixed thread count) forked: yes (variable process count) Server compiled with.... -D APR_HAS_SENDFILE -D APR_HAS_MMAP -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled) -D APR_USE_SYSVSEM_SERIALIZE -D APR_USE_PTHREAD_SERIALIZE -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT -D APR_HAS_OTHER_CHILD -D AP_HAVE_RELIABLE_PIPED_LOGS -D DYNAMIC_MODULE_LIMIT=256 -D HTTPD_ROOT="/etc/apache2" -D SUEXEC_BIN="/usr/lib/apache2/suexec" -D DEFAULT_PIDLOG="/var/run/apache2.pid" -D DEFAULT_SCOREBOARD="logs/apache_runtime_status" -D DEFAULT_ERRORLOG="logs/error_log" -D AP_TYPES_CONFIG_FILE="mime.types" -D SERVER_CONFIG_FILE="apache2.conf" ** Affects: apache2 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1565744 Title: "Mutex file:${APACHE_LOCK_DIR} default" should be disabled by default on Linux because it leads to errors To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apache2/+bug/1565744/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs