Outgoing messages are more than incoming messages in Event Hub when using EventProcessorHost

Asked Mar 25 '20 at 16:50

Active Mar 25 '20 at 17:05

Viewed 2,559 times

I am using Azure Event hub. Outgoing messages from Event hub are processed by application using EventProcessorHost. Event hub has one consumer group i.e. $Default. I am seeing outgoing messages are more than incoming messages. Not sure why outgoing is more than incoming in Event hub.

edited Mar 25 '20 at 17:05

asked Mar 25 '20 at 16:50

Amit Agrawal

maybe your processors are reprocessing messages either when restarting or when scaling out before certain messages have been properly checkpointed. Your app should be resilient to this. Event Hub is "at least once delivery" – silent Mar 25 '20 at 17:20
there is no retry logic written in our app. Not sure EventProcessorHost does retry or not. – Amit Agrawal Mar 25 '20 at 17:21
I did not say retry. I said restart. EH-processorhost uses blob storage for checkpointing. Depending on how often you checkpoint, it can happen that you read the same message more than once. this is to be expected in high volume scenarios – silent Mar 25 '20 at 17:23
Our code is not using CheckpointAsync() so EH-processorhost does automatically checkpointing . Please confirm. – Amit Agrawal Mar 25 '20 at 17:27
nope. it does not do that, except for when closing the connection. if you do not checkpoint yourself in between, you have a no-no! – silent Mar 25 '20 at 17:30
then why outgoing is more than incoming ? – Amit Agrawal Mar 25 '20 at 17:33
because you are reading some messages more than once. – silent Mar 25 '20 at 17:38
now question comes, In which situation it is happening ?? – Amit Agrawal Mar 25 '20 at 17:43
How many processor hosts are you running with? – Serkant Karaca Mar 25 '20 at 22:02
6 processors are running. – Amit Agrawal Mar 26 '20 at 05:16

Outgoing messages are more than incoming messages in Event Hub when using EventProcessorHost

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