Hello all, I just realized that in the windowing implementation, we use an additional thread as a timer for processing time triggered windows:
https://github.com/apache/storm/blob/master/storm-client/src/jvm/org/apache/storm/windowing/TimeTriggerPolicy.java#L71 We also do the same thing in: https://github.com/apache/storm/blob/master/storm-client/src/jvm/org/apache/storm/windowing/WaterMarkEventGenerator.java#L71 to periodically generate watermarks. Perhaps, instead of additional threads we can just use tick tuples for such triggering of events? Or we can allow registration of timers and callback functions in topologies so that additional timer threads would be not be needed? I know that the tick tuple frequency is in seconds and windowing supports millisecond granularity but the tick tuple frequency can easily be changed to support millisecond frequency. On the other hand, a more eloquent solution would be having an API that allows users to register arbitrary timer events in their topologies. Something like this: conf.registerTimer(long frequency, Object callback) Anyone have any thoughts on this? Best, Jerry
