[SOLVED] restarting mysql via /etc/init.d/mysqld restart

wills · 03-07-2012, 01:10 PM

This morning I had to restart the MySQL service because someone in our organization couldn't do it for some reasons. The person that asked me to restart had made my.cnf configuration changes. There was nothing really wrong with the server other than he couldn't restart it.

Shortly, after doing this, I got an email with the following from someone else:

Quote:

It is my understanding that mysqld restart is a cold and rude shutdown, the equivalent of a crash, on production, do this only if you have no other choice. Instead use mysqladmin shutdown to stop the service and mysqld start to start it.

Is there any merit to this statement?

thinknix · 03-07-2012, 02:55 PM

False. At least on Debian, the mysql init script handles a restart action by first trying to send a SIGTERM to the mysqld process to gracefully stop it (EDIT: Just checked a CentOS 5.4 box, it also sends an initial SIGTERM). Only if the process does not respond to the initial SIGTERM does it issue the SIGKILL, which would be forceful (and necessary at that point). The mysql documentation specifically mentions using SIGTERM to shutdown mysql on Unix-based OSes (from http://dev.mysql.com/doc/refman/5.0/...hutdown.html):

Quote:

1. The shutdown process is initiated.

This can occur initiated several ways. For example, a user with the SHUTDOWN privilege can execute a mysqladmin shutdown command. mysqladmin can be used on any platform supported by MySQL. Other operating system-specific shutdown initiation methods are possible as well: The server shuts down on Unix when it receives a SIGTERM signal.