Hi ALL,
An executor is a thread that is spawned by a worker process. It may run one or more tasks for the same component (spout or bolt). A task performs the actual data processing ― each spout or bolt that you implement in your code executes as many tasks across the cluster. The number of tasks for a component is always the same throughout the lifetime of a topology, but the number of executors (threads) for a component can change over time. This means that the following condition holds true: #threads ≤ #tasks. By default, the number of tasks is set to be the same as the number of executors, i.e. Storm will run one task per thread. http://storm.apache.org/documentation/Understanding-the-parallelism-of-a-Storm-topology.html According the above, the executor run one or more spout or bolt. Could you tell me the life cycle of executor and spout? Could you tell me a use case about executor has more than one task. When the executor need more than one task? Thanks a lot. Regards, Peter
