My server is keep doing graceful restart every now and then. How can I fix this. Here is my server log:
It looks like a cron event is being triggered every hour to restart Apache, which is why the events are almost exactly one hour apart. If you have a control panel, you should access the cron events for your server. It is possible the restart is inside a bash script, but you should be able to see which cron events are scheduled to run on an hourly basis.