The sw-engine process causes high CPU usage on a Plesk server

Symptoms

• The sw-engine process causes high CPU usage:

  # ps aux | grep sw-engine
  root 1242 0.0 0.3 348136 28732 ? Ss Jan14 0:14 /usr/bin/sw-engine -c /usr/local/psa/admin/conf/php.ini /usr/local/psa/admin/bin/modules/watchdog/wdcollect -c /usr/local/psa/etc/modules/watchdog/wdcollect.inc.php
  root 2315 0.0 0.1 353260 9908 ? Ss Jan14 0:00 sw-engine-fpm: master process (/etc/sw-engine/sw-engine-fpm.conf)
  root 3136 0.0 0.3 363840 32028 ? S Jan14 1:00 /usr/bin/sw-engine -c /usr/local/psa/admin/conf/php.ini /usr/lib64/plesk-9.0/psa-health-monitor-notification.php

• Plesk may fail to load with a 502 error.

Cause

Some sw-engine child processes are stuck and cannot be stopped normally.

Resolution

1. Connect to the Plesk server via SSH.

2. Stop the sw-engine service:

   # service sw-engine stop
   Stopping sw-engine-fpm: [ OK ]

3. Find stuck sw-engine processes and their PID:

   # ps aux | grep sw-engine
   psaadm 1597 0.0 2.1 274896 44100 ? Ss 12:39 0:00 /usr/bin/sw-engine -c /usr/local/psa/admin/conf/php.ini /usr/local/psa/admin/plib/WebSocket/bin/ws-server.php
   psaadm 1842 0.0 2.3 278952 49564 ? S 12:42 0:00 /usr/bin/sw-engine -c /usr/local/psa/admin/conf/php.ini /usr/local/psa/bin/extension --exec revisium-antivirus ra_executor.php

4. Kill these stuck processes using their PID. In the example above, they are 1597 and 1842:

   # kill -9 1597 1842

5. Start the sw-engine service:

   # service sw-engine start
   Starting sw-engine-fpm: [ OK ]