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Hello,
We have a HTTP Trigger Azure Functions and started stumbling across 429 Too many request errors, once we upgraded our Azure Functions to the v4.
We were running some performance tests on this function, and after a specific throughput, we started receiving this error. Luckily, in an old resource group, we still had a function that was running on the v2 and did the same test on this function as well. We've compared the results experienced with the data from v2 functions and while we got 429 statuses in that version as well, they were occurring way past this throughput value of 6,000/sec and also in a smaller percentage throughout the test execution.
Based on our tests we received the following results:
| v4 | v2 |
|---|---|
| 1 million calls | 1 million calls |
| 10857 throughput / s | 5242.5 throughput / s |
| 53.62 % Error Rate ( 429 - error code ) | 0 % Error Rate |
The tests were executed using the same configuration of threads, ramp-up, and loops. The high throughput in the v4 test run is caused by the error rate.
The code is the same, nothing major has changed inside our function, it does the same things, and the response time is the same ( milliseconds ).
Both were running on a Consumption service plan.
The Application Insights doesn't log anything regarding this error, in the logs for the App Service Plan we can't see anything wrong, basically this error is not traced anywhere.
We are expecting high traffic on our website in the upcoming period and we need to get ready to handle the worst-case scenario.
Do you know if anything has changed in terms of rate limit or were there any hard limits imposed on the Azure functions since v4 has been released?
If so, is there any way I can increase that limit?
If any more details are required in order to troubleshoot the problem, please let me know and I can provide them.
Thanks a lot!
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Sebastian Cocîrlă Thanks for posting your question in Microsoft Q&A. Azure Functions limits are documented here and if the limits such as outbound connections, request size etc. are exceeded you might get the errors. We have doc: Throttling that talks about throttling and the control over configuration via host.json.
Have you tried Azure Diagnostics to troubleshoot this issue? If not, suggest you follow doc https://learn.microsoft.com/en-us/azure/azure-functions/functions-diagnostics and review the errors/exceptions. If it doesn't help, please open a support ticket with azure support team and they have the best tools and resources to investigate the backend logs to find the cause. If you don't have support plan, let me know.
Azure Functions have some limits, including for HTTP triggered functions. It's possible that you're hitting these limits.
You can check from the following link
Hi Sedant,
Thank you for your reply.
Indeed I have read about the limitations of these functions, but I could find anything specific about this. Especially, about the requests limits...