I recently noticed that every time logrotate rotated the logs on one of my servers, the apache process on that machine seemed to just stop logging to the log files.
The problem seems to have been caused because I'd accidentally deleted the line
from the logrotate conf file
/etc/logrotate.d/httpd. This meant that logrotate was compressing the log file while apache was sometimes still writing to it, with the result that apache failed to switch to writing to a new clean logfile.
The man page says: