sun.jvmstat.perfdata.monitor.AliasFileParser calls an internal debug logging method that always discards the input string since logging is disabled. Unfortunately the input strings are still constructed which causes a lot of allocation due to string concatenation.

The logging method is:
    private void logln(String s) {
        if (DEBUG) {
            System.err.println(s);
        }
    }

It is permantently disabled since:
    private static final boolean DEBUG = false;

An example of a call to the logging method:
            logln("matched type: " + ttype + ", token = " + currentToken.sval);

This could quite easily be fixed by either removing the logging completely or by guarding the logln calls in "if (DEBUG)" blocks.