We are seeing higher than normal latencies of around 4 seconds per request when sending events to Azure Event Hub. .

Question

We send around 500k - 600k events through Azure Event Hub per day. Over the past week, we have seen our latencies for sending events to Event Hub increase to ~4 seconds per call. I thought that perhaps we were hitting some Throughput Units. But our Event Hub namespace has Auto Scale on and is not yet at its Autoscale max. We have very few server errors and no event throttling according to Azure Metrics.

Answer 1

@Steve Bering

Greetings & Welcome to Microsoft Q&A forum! Thanks for posting your query!

The increased latency you are experiencing when sending events to Azure Event Hub could be attributed to several factors, even if you have Auto Scale enabled and are not hitting the maximum throughput units. Here are a few considerations:

Load Distribution: If the load isn't evenly distributed across all partitions, it can lead to one partition hitting its local throughput limit, which may cause increased latencies. You might want to review your partition distribution strategy.

Throughput Units: While Auto Scale is designed to adjust the throughput units based on demand, it may not always react immediately to sudden spikes in traffic. Ensure that your current throughput units are sufficient for your usage patterns.

Network Latency: External factors such as network latency or issues with the client application can also contribute to increased request times. It might be worth checking the network performance and the configuration of your sending application.

Event Hub Metrics: Even though you mentioned that there are few server errors and no event throttling, it's still beneficial to monitor the metrics closely to identify any unusual patterns or spikes in usage that could correlate with the increased latencies.

For more details, please refer the following documentations that might help you:

https://learn.microsoft.com/en-us/azure/event-hubs/event-hubs-messaging-exceptions

https://learn.microsoft.com/en-us/azure/event-hubs/event-hubs-scalability#scaling-with-event-hubs

I hope this information helps. Please do let us know if you have any further queries.

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Thank you.