- The MR AppMaster should only use port ranges defined in the yarn.app.mapreduce.am.job.client.port-range property. On initial startup of the MRAppMaster, it does use the port range defined in the property. However, it also opens up a listener on a random ephemeral port. This is not the Jetty listener. It is another listener opened by the MRAppMaster via another thread and is recognized by the RM. Other nodes will try to communicate to it via that random port. With firewall settings on, the MR job will fail because the random port is not opened. This problem has caused others to have all OS ephemeral ports opened to have MR jobs run.
This is related to