Service CCS cpanel-ccs is generating high CPU processes

Symptoms

Note: In cPanel & WHM version 120, we deprecated and removed the Calendar and Contacts Server (CCS) plugin. We also added support for CalDAV (calendars) and CardDAV (contacts) to the cpdavd service.

In the WHM process manager, cPanel-ccs is generating a high CPU.

CONFIG_TEXT: PID = 3541 = cPanel-ccs = 80.47% CPU USAGE =
/opt/cpanel-ccs/.develop/virtualenv/bin/python 
/opt/cpanel-ccs/.develop/virtualenv/bin/twistd

Additionally, it can be observed that the pid files for the CalDAV service are either empty or invalid. This information is shown in the CCS error log.

Logfile path: /opt/cpanel-ccs/data/Logs/error.log

CONFIG_TEXT: 2021-03-13T14:15:30+0800 [caldav-0] Reading configuration from file:
/opt/cpanel-ccs/conf/caldavd-dev.plist 
2021-03-13T14:15:30+0800 [caldav-0] Pidfile 
/opt/cpanel-ccs/data/Logs/state/caldav-instance-0.pid contains 
non-numeric value \

The log file could also indicate that another twistd server is running.

CONFIG_TEXT: 2026-05-21T17:08:56+0200 [caldav-24] Reading configuration from file: /opt/cpanel-ccs/conf/caldavd-dev.plist
2026-05-21T17:08:56+0200 [caldav-24] Another twistd server is running, PID 1660 
2026-05-21T17:08:56+0200 [caldav-24] This could either be a previously started instance of your application or a 
2026-05-21T17:08:56+0200 [caldav-24] different application entirely. To start a new one, either run it in some other 
2026-05-21T17:08:56+0200 [caldav-24] directory, or use the --pidfile and --logfile parameters to avoid clashes.

Cause

If the server has recently restarted or recovered from an issue and left behind empty or stale pid files, it could prevent the startup from being successful.

The files would be empty or not contain numeric values. No output would be received when running the commands below, indicating the files are empty. It's possible the files contain non-numeric values.

# cat /opt/cpanel-ccs/data/Logs/state/caldav-instance-0.pid

When empty Instance pid files are present, this high usage is increased and does not go away automatically.

Resolution

1. Clear all instance pid files.

   # /bin/rm -v /opt/cpanel-ccs/data/Logs/state/caldav-instance*

2. Restart the service.

   # /scripts/restartsrv_cpanel_ccs