What is the Http queue length metric on Azure Web App?

Question

What is the Http queue length metric on Azure Web App ?

My Web App is constantly over 150.

I'm concerned since the default Alert that can be enabled on the App Service has a default threshold of 100.

Could the usage of SignalR affect this metric ?

EDIT:

Here is typical day load:

Answer 1

EDIT 11/12/2016

Based on some follow up information HTTP Queue Length will at some point soon here match up with expectations.

I got confirmation that after the fix, the HTTP Queue Length metric for Server Farm will be depicting the actual HttpQueueLength ( it is incorrectly showing the current Requests value at this time) for the Server Farm (App Service Plan). This fix will be rolled out in the coming weeks across all regions .

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In talking with Azure Support HTTP Queue Length is actually a confusing name and maps to ''W3SVC_W3WP', 'Active Requests', '_Total'.

Here's the full response

Hello Shane, You are correct, we had noticed an issue with http queue metric , where we found out that in Auto-Scaling/Alert a Web App based on this metric was misleading as this metric was calculating the total active requests and not the queued requests and we had a discussion with our Product team about this metric and it appears that there is a little bit of ambiguity in the name of the metric HTTP Queue. In reality, the counter does we show on the portal corresponds to "W3SVC_W3WP", "Active Requests", "_Total". In other words, this counter does not represent a queue but rather requests that are running at any current time. We have also verified this by looking into our Product source code. We understand how the name of the counter could lead to confusion and we have submitted a request to our Product team to rename it. The Product team is concerned that renaming might break existing alerts customers might have but they are considering adding another metric named “Active Requests” which looks at the same value and later removing “HTTP Queue Length”. Keeping this in mind, our suggestion was to use any other metric (for example: CPU/Memory) to configure Auto-Scale/Alert rules instead of using Http Request Queue.

I had a discussion with our Product team just a few days back again and we are currently in the works on having this updated to represent that the counter value is for “Requests” and not the true Http Queue Length.

Though this distinction will soon be irrelevant as they also had this to say

Hi Shane, I was just testing this out on my end and I see that the portal has been updated at the Site level to show this metric as “Requests” . I think we are still waiting for this change to be pushed out to the Server Farm settings.

If I select Alert . In the “Resource” drop down select “sites” to select your site, then the metrics will list “Requests” , which will be the current requests.

So just something to be aware of that in its current state this metric does not indicate that you have requests backing up that the system can't handle.