JavaMelody statistics is cleared after tomcat restart

[alexbudarov]

How to reproduce:

• Deploy application with JavaMelody to a linux tomcat service. E.g. Ubuntu 18.04, "tomcat8" package.
• Run for a while
• Restart tomcat
• Open /core-jm/ page again.

You will see that all graphs have been reset:

The reason is because JavaMelody by default stores its data in a temp directory. E.g. tomcat/temp/javamelody in tomcat-fast-deployment.
And linux tomcat service cleans temp directory on every server restart - which is reasonable thing. So javamelody stats are cleared during every tomcat service restart.

Suggestion: place javamelody stats to other place, e.g. work directory.