We've recently seen
IMPALA-5809 reoccurring. One possibility is that our test-infrastructure recently got slower and we are now hitting the default 5 second timeout in wait_for_num_processes. There could also be a more fundamental issue leading to hangs. To rule this out, we should increase the default timeout to something larger to allow the tests to complete. If that doesn't help, we should consider adding debugging code to get more information when hitting this.