High Water Mark
High Water Mark throttle is similar to the Rate throttle, but this throttle also decrements the count after the passed on requests are completed and the response is ready to return to the requester.
The High Water Mark throttle increments the throttle count on the request and decreases the throttle count once the response for that request is sent. Define a throttle max count for a high water mark throttle. Using the High Water Mark throttle, you can process a specific number of requests in parallel by a target service.
Example
High water mark throttle can be defined when the requests are sent in parallel by different users to a target operation. The target operation is slow in responding to such requests sent to it in parallel.
For example, if you want to send five requests to a target operation A by five users concurrently, define the throttle configuration for a target operation on the Config UI as follows. The following throttle configuration allows only five parallel requests to be served by a target operation A at a time, with this throttle configuration.
Max Limit: 5 Type: High Water Mark Throttle