Azure LanguageAPI Rate Limit Alert

Question

Azure LanguageAPI Rate Limit Alert

Umer Rashid 150

Hello,

I set up an Azure Alert to monitor rate limit of Azure Language API.

On 26 March, the alert was triggered as the rate limit value reached 31.78k requests, as shown in the attached screenshot, and there was a delay of around 40 minutes in receiving the responses. However, we did not receive any HTTP 429 errors.

Can you please explain why there were no HTTP 429 error under this situation? Also I am wondering what are the recommended measures to handle such situations in future.

Thanks,

Umar

Screenshot 2025-04-03 at 14.11.23

santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-03T10:54:34.64+00:00

Hi @Umer Rashid,

It looks like your Azure alert triggered because the Language API hit 31.78k requests, but you didn’t get any HTTP 429 errors. This could be due to a few reasons. Azure often allows short bursts beyond the stated rate limit, meaning it can handle temporary spikes before enforcing strict limits. Your alert might also be based on a predefined threshold rather than the actual API limit, so it may have flagged the spike even though the API was still handling requests. Also, rate limits can vary depending on the Azure region and pricing tier you’re using.

Another factor to consider is how Azure internally processes requests. Some APIs implement adaptive rate limiting, where they only enforce strict limits when sustained high traffic is detected over a longer period. Additionally, delays in processing or network congestion could have contributed to the alert, even if the API itself didn’t reject any requests.

If you notice frequent delays or unexpected API behaviour, you can check for potential Azure service incidents on the Azure Service Health dashboard or analyze API response times using Azure Monitor.

I hope you understand! Thank you.
santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-04T14:54:30.0166667+00:00

Hi @Umer Rashid,

Following up to see if the given response was helpful. And, if you have any further query do let us know. Thank you.
santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-07T08:58:01.96+00:00

Hi @Umer Rashid,

We haven’t heard from you on the last response and was just checking back to see if the given response was helpful. And, if you have any further query do let us know.

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santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-03T10:54:34.64+00:00

Hi @Umer Rashid,

It looks like your Azure alert triggered because the Language API hit 31.78k requests, but you didn’t get any HTTP 429 errors. This could be due to a few reasons. Azure often allows short bursts beyond the stated rate limit, meaning it can handle temporary spikes before enforcing strict limits. Your alert might also be based on a predefined threshold rather than the actual API limit, so it may have flagged the spike even though the API was still handling requests. Also, rate limits can vary depending on the Azure region and pricing tier you’re using.

Another factor to consider is how Azure internally processes requests. Some APIs implement adaptive rate limiting, where they only enforce strict limits when sustained high traffic is detected over a longer period. Additionally, delays in processing or network congestion could have contributed to the alert, even if the API itself didn’t reject any requests.

If you notice frequent delays or unexpected API behaviour, you can check for potential Azure service incidents on the Azure Service Health dashboard or analyze API response times using Azure Monitor.

I hope you understand! Thank you.
santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-04T14:54:30.0166667+00:00

Hi @Umer Rashid,

Following up to see if the given response was helpful. And, if you have any further query do let us know. Thank you.
santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-07T08:58:01.96+00:00

Hi @Umer Rashid,

We haven’t heard from you on the last response and was just checking back to see if the given response was helpful. And, if you have any further query do let us know.

Answer 1

Umer Rashid 150

Hi @santoshkc Thanks for the prompt response.

Yes, that explanation has been very helpful.

Can you please also explain what are recommended measures to ensure scalability with Azure Language AI API, especially to handle such situations related to rate limiting?

santoshkc 14,415 Reputation points Microsoft External Staff

2025-04-08T12:37:23.8+00:00
Hi @Umer Rashid,

To ensure scalability and handle rate limiting effectively with Azure Language AI API, here are some recommended best practices:

Distribute Requests: If possible, spread your API calls more evenly over time instead of sending them in bursts. This can help avoid triggering rate limits.

Monitor Usage & Set Alerts: Continue using Azure Monitor and alerts, just make sure the alert thresholds align closely with your actual subscription limits.

Scale via Concurrent Resources: For heavy workloads, consider scaling horizontally by using multiple resources or regions. This can help balance the load.

Batch Processing: Where possible, batch your requests (e.g., analyze multiple documents in a single call) to reduce the number of API hits.

Additionally, refer best practices here.

I hope this helps! Thank you.

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Azure LanguageAPI Rate Limit Alert

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