Is there any pattern to this? For ex., do the few tasks that hang all run on the same host or specific set of hosts among all nodes in the cluster? A more detailed root cause can be sought by performing a jstack on a task that appears hung live. This is done by first finding which host the hung task is running on (within the task timeout period, after noticing it hanging), discovering its container ID and finding the associated java process on the machine followed by the jstack command run on the PID. ... View more