The supervisor log you posted covers multiple different workers... This looks expected to me. If an unhandled exception occurs in a worker, it will die. Then either nimbus or the supervisor will cease to see its heartbeats, the supervisor will attempt to kill it, then nimbus will ask a supervisor to start a new worker.
The most relevant logs are in the worker log. I'm betting the problem is connected to "thrift connection timeout". Sorry I couldn't be of more help.
