MySQL still holding memory after I shut it down?

Question

I used this command to shutdown MySQL, however it seems the amount of free memory on my box has not changed?

That seems to odd.

/usr/local/webserver/mysql/bin/mysqladmin -u ${mysql_username} -p${mysql_password} -S /data0/mysql/mysql.sock shutdown

Does anyone know why the free memory might not change very much after unloading MySQL?

Answer 1

Linux systems always try to use a much ram as available for various functions like caching of executables our even just page reads from disk. That's what you bought your fast RAM for after all.

You can find out more about your system by doing a

cat /proc/meminfo

More info in this helpful blog post If you find out a lot is used in cache then you don't have to worry about the system. Like Kormoc says the difference is no doubt the fact that certain pages on disk are still cached and will stay cached for a while until the system needs memory or some other settings deem it unnecessary to cache for read-access anymore.

Answer 2

Memory management is a complex beast. If you are on a linux or similar platform, you might be seeing differences because of the page cache. This is a good writeup of what the page cache is.