In the jdk.internal.jvmstat module, the LocalVmManager(String user) constructor is supposed for be used to look for VMs owned by the user. See

https://github.com/openjdk/jdk/blob/b1b83500a9c3a74bf39894e49eefd031d208b9b9/src/jdk.internal.jvmstat/share/classes/sun/jvmstat/perfdata/monitor/protocol/local/LocalVmManager.java#L77

However, no code calls this constructor. Also, even if LocalVmManager.userName is set, the current implementation doesn't look for VMs owned by this user.

This constructor should be removed, as well as all code that depends on LocalVmManager.userName.

There's related unused code in the PerfDataFile class in the same package.