I created A Snapshot for FreeMemory with the web-console with Time Period 1000, start the snapshot in the web-console wih Start Snapshot and wait for a few minutes. Pressing the button Show Dataset show me the values.
When Pressing the button Show Dataset in the web-console Jboss breaks immediatly and killed every running JBoss tasks. In the console where I started Jboss stand the following:

X11 connection rejected because of wrong authentication.

In the Logfile from Jboss for STDOUT stand the following:

X connection to localhost:12.0 broken (explicit kill or server shutdown).

In server/all/log/server.log I cannot find anything belong to this error.