Low java run-time memory

hello, just wanna ask why is it every time i browse the server for open fire, the java runtime memory gets low in space? how can i prevent it from being low? is the users of spark will get affected to?

thanks

Which version of openfire are you using?

How much memory you have for Java?

How many users connected to your server?

My server is 3.6.4 with an uptime of 37 days:

using 57.80 Mb out of 512 Mb (11.3% used)