CR 6437701 is fixed for JDK7, but still occurs with JDK6:

On Windows when TMP variable is set to nonexistent directory, NullPointerException is thrown:

> set TMP=n:\nonexistent
> jps

Exception in thread "main" java.lang.NullPointerException
        at sun.jvmstat.perfdata.monitor.protocol.local.LocalVmManager.activeVms(LocalVmManager.java:127)
        at sun.jvmstat.perfdata.monitor.protocol.local.MonitoredHostProvider.activeVms(MonitoredHostProvider.java:133)
        at sun.tools.jps.Jps.main(Jps.java:45)