How does limit concurrency works in azure APIM

Question

This is what i am trying to set in policy
<backend>
<limit-concurrency key="@(context.Request.IpAddress)" max-count="10" max-queue-length="100">
<forward-request />
</limit-concurrency>
</backend>

I want to know below questions

1. What happens when request exceeds the max count ? will the 11th request be retry ?
2. To queue the request and shoot them after concurrency period i amd setting max-queue-length and i am getting below error

Answer 1

@Suresh Thakur, Kirti ,

Thanks for reaching out to Q&A.

The limit-concurrency policy prevents enclosed policies from executing by more than the specified number of requests at any time. Upon exceeding that number, new requests will fail immediately with 429 Too Many Requests status code. So the 11th request will fail with status code 429.

In order to resolve the max-queue-length error, please try to set a timeout attribute in between max-count and max-queue-length.

<limit-concurrency key="expression" max-count="number" timeout="in seconds" max-queue-length="number">
<!— nested policy statements -->
</limit-concurrency>

I hope this helps!

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