Warning when restarting a service: UID 0 clobbered stale lock file

Question

While restarting a service, I see a warning mentioning a clobbered stale lock file similar to the following:

[2021-01-09 12:00:00 -0500] warn [rebuildhttpdconf] [12345] TIME 1610252525 UID 0 clobbered stale lock file “/etc/apache2/conf/httpd.conf.lock” (NAME “queueprocd - process - apache_restart - safeaprestart - locking config”, UID 0) written by PID 012345 at 1610252525 at 

[backtrace follows]

What does this indicate, and should I be concerned?

Answer

These warnings can occur when a service such as Apache is restarting. In the example above, a rebuild of the Apache configuration encountered a lock file for a process that no longer existed. The lock file was removed, or "clobbered", so Apache could start successfully after the rebuild.

Determining why the stale lock file was left behind initially can be a difficult task. Provided that there are no issues with the service after the warning, there should be nothing to be concerned about.