CODEWITHSUNDEEP
asp.netperformanceiisasp.net-web-api
Afshar
Afshar

Reputation: 11543

IIS/ASP.NET intentionally responds simultaneous requests slower than single ones?

IIS (or maybe ASP.NET) takes longer time to respond requests when they are sent simultaneously with other requests. For example if a web page sends request A simultaneously along with 20 other requests, it takes 500 ms but when this request is sent lonely, it takes 400 ms.

Is there a name for this feature? It is in IIS or ASP.NET? Can I disable or change it? Is there any benefits using it?

Notes:

Update 1: All requests are going to read something from database. I have checked them in Chrome developers' console. Also created a simple C# application that makes multiple parallel requests to the server. When they are really parallel, they take a large time, but when makes wait between each call, the response time decreases dramatically.

Update 2: I have a simple method in my application that just sends an Ok:

[AllowAnonymous]
public IHttpActionResult CheckOnline()
{
    return Ok();
}

Same behavior exists here. In my custom C# tester, if I call this route multiple times simultaneously it tokes more than 1000 ms to complete but when wait 5 seconds between each call, response time drops below 20 ms. This method is not IO or CPU bound. Seems that IIS detects that these requests are from a single specific user/client so do not make too much attention to it.

Upvotes: 3

Views: 1724

Answers (1)

Vladimir
Vladimir

Reputation: 853

If you use ASP.NET Session in your application, requests are queued and processed one by one. So, the last request can stay holt in the queue while the previous requests are being processed.

Another possible reason is that all threads in the ASP.NET Thread Pool are busy. In this case, a new thread will be created to process a new request that takes additional time.

This is just a theory (or my thoughts). Any other cause is possible.

Upvotes: 1

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