Only a single instance of IEventProcessor gets created? about azure-event-hubs-java HOT 5 CLOSED

thanks for raising this and pinging me. I'm muy interested this thread!

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An instance of EventProcessorHost creates an instance of IEventProcessor for every partition that it holds the lease for. A given instance of IEventProcessor is created when the EPH instance gets the lease for a partition and is permanently tied to that partition, being shut down and destroyed if and when the EPH instance loses the lease, or the EPH instance as a whole is shut down.

The loop at PartitionManager.java:423 iterates through all the leases and calls Pump.addPump() for each partition that this EPH instance owns. If there already is a pump for that partition, Pump checks its health and restarts if necessary (Pump.java:42); if there isn't one, it creates a new pump (Pump.java:54). Pump.createNewPump() creates a new instance of EventHubPartitionPump and starts it at Pump.java:60-61. The method startPump() is actually implemented on the parent class PartitionPump, and the processor factory is called to create a new IEventProcessor at PartitionPump.java:52.

from azure-event-hubs-java.

Thanks James.

This does not corroborate with my observations. As I said, constructor of my IEventProcessor gets called once while I have a single host working off 8 partitions. I guess the next step is to have a repro?

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A moment of clarification: what I describe is the behavior of the default IEventProcessorFactory. If you implement your own and call EventProcessorHost.RegisterEventProcessorFactory with it, then any pattern is possible. A user-implemented factory is free to only ever create one IEventProcessor instance and just dispense that instance whenever it is called to create an event processor. We have heard from customers who are doing exactly that.

I assuming that you are NOT doing a custom factory -- if you were, you'd know why your constructor was being called only once! For the default factory, the behavior is supposed to be as I describe, and if you can repro it failing, we would love to see that and fix it.

Thanks!

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Thanks James.

You are absolutely correct. I created a bare-bone example and I can see, as you said, we get an instance per partition.

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