on ResourceAwareScheduler not working properly.
With default cluster settings, there will be only one __acker-executor and it will be on a separate worker. And it looks like the __acker-executor was not able to receive messages from spouts and bolts. And spouts and bolts continued to retry sending messages to acker. It then led to another problem:
I tried to run on storm right before https://github.com/apache/storm/pull/2502 and right after and confirmed that this bug should be related to it