I have an application which uses LocalJobRunner to process MR Jobs. From the heap dump of my application I can see multiple object with Name $Proxy90; happens to be created by org.apache.hadoop.metrics2.impl.MetricsSystemImpl.register(Callback).
Every-time a LocalJobRunner is launched it creates JobTrackerInstrumentation and QueueMetrics.
While creating this MetricsSystem ; it registers and adds a Callback to ArrayList which keeps on growing as the DefaultMetricsSystem is Singleton. Is it a known bug? Is there any workaround to empty this list?