I'm logging Python print statements to /var/log/apache2/error.log, but in the past few days I've discovered when I tail the log NOTHING. Web requests ARE being handled normally.
sudo apachectl restart restores logging to functioning.
At the end of the previous log (error.log.1, which contains proper logging) there is this notice:
[Wed May 24 18:27:04.070726 2017] [mpm_event:notice] [pid 1903:tid 139769062209408] AH00494: SIGHUP received. Attempting to restart
I understand this notice is probably related to log rotation. I presently have 52 older logs, but I have plenty of disk space (I'v used 63.7% of 7.74GB).
The odd thing is this started happening when I first used apachectl graceful-stop. And each time it has happened, the log is rotated, but at that point nothing new goes into the log, until I manually RESTART apache.