HTTP Service Request Queues Test

By monitoring request queues to every Exchange application pool, administrators can identify those application pools that have too many requests pending and those with a high request rejection rate. This is exactly what the HTTP Service Request Queues test does. This test auto-discovers the application pools and reports the length of request queues and rejection rate of requests in queue for each application pool. This way, the test sheds light on those application pools that suffer from processing pains.

Target of the test : A Microsoft Exchange 2013/2016 server

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for every application pool on Exchange

Configurable parameters for the test
  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. port – The port at which the host listens.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Requests arrival rate:

Indicates the rate at which requests are arriving in the request queue of this application pool.


A high rate could indicate a probable request overload on an application pool.

Requests in queue:

Indicates the current number of requests in the queue of this application pool.


If this value increases consistently, it could indicate that the application pool is not processing requests quickly. Compare the value of this measure across pools to identify the pool with a processing bottleneck. 

Requests rejected from queue:

Indicates the number of requests in this application pool’s queue that were rejected. 


A non-zero value is desired for this measure.

Cache hit rate:

Indicates the rate of cache hits from the queue of this application pool.



Request rejection rate:

Indicates the rate at which this application pool rejected requests in the queue.


Compare the value of this measure across pools to know which pool rejects queued requests frequently.

Maximum queue item age:

Indicates the age of the oldest request in the queue.