Next just contact springboot soon, in the company's project after deployment is the Java - jar XXX. Perform jar jar package, but see online a lot of posts in Java - after the jar to bring - Xms, -xmx, Xss these limits the JVM memory parameters, next is wondering why restrict the JVM memory, the JVM is not have any garbage collection mechanism, the program should use how much memory is how much memory, why must significantly restrict the use of memory size, if not add these parameters will have what problem