What is the difference between apache2 reload, restart, graceful?

Question

I am using apache2 for a project and I am wondering what is exactly the difference between these commands:

service apache2 restart service apache2 reload service apache2 graceful 

Answer 1

There main difference between the four different ways of stopping/restarting are what does the main process do about its threads, and about itself.

Note that Apache recommends using apachectl -k as the command, and for systemd, the command is replaced by httpd -k

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apachectl -k stop or httpd -k stop

This tells the process to kill all of its threads and then exit

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apachectl -k graceful or httpd -k graceful

Apache will advise its threads to exit when idle, and then apache reloads the configuration (it doesn't exit itself), this means statistics are not reset.

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apachectl -k restart or httpd -k restart

This is similar to stop, in that the process kills off its threads, but then the process reloads the configuration file, rather than killing itself.

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apachectl -k graceful-stop or httpd -k graceful-stop

This acts like -k graceful but instead of reloading the configuration, it will stop responding to new requests and only live as long as old threads are around. Combining this with a new instance of httpd can be very powerful in having concurrent apaches running while updating configuration files.

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Source: https://httpd.apache.org/docs/2.4/stopping.html

Recommendation: Use -k graceful unless there is something wrong with the main process itself, in which case a combination of -k stop and -k start or -k graceful-stop and -k start are the options of choice.

Answer 2

1. Difference between “restart” and “reload”

   • Restart= stop + start
   • Reload = remain running + re-read configuration files.

2. Normal restart and graceful restart, you can reference article:

   https://teckadmin.wordpress.com/2013/10/23/difference-between-graceful-restart-and-normal-restart/