CODEWITHSUNDEEP
asp.net-core
Maven Cheong
Maven Cheong

Reputation: 103

ASP.NET Core, how it handle concurrent request when async involved?

Any idea how ASP.net core handle concurrent request when a async involved. As you can see from the log below, the request finished time seem like in sequence rather than in parallel or concurrently? I might understand the async wrong, hope someone can explain why below request finished timing is in sequence rather identical timing? I was expecting at least each of the request should finish in almost identical time?

Connection id "0HL9BC18TNP25" started.
Connection id "0HL9BC18TNP26" started.
Connection id "0HL9BC18TNP27" started.
Connection id "0HL9BC18TNP28" started.
Connection id "0HL9BC18TNP29" started.
Connection id "0HL9BC18TNP2A" started.
Connection id "0HL9BC18TNP2B" started.
Connection id "0HL9BC18TNP2C" started.
Connection id "0HL9BC18TNP2D" started.
Connection id "0HL9BC18TNP2E" started.
Connection id "0HL9BC18TNP2C" completed keep alive response.
Request finished in 45.2835ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP2C" received FIN.
Connection id "0HL9BC18TNP2C" disconnecting.
Connection id "0HL9BC18TNP2C" sending FIN.
Connection id "0HL9BC18TNP2C" sent FIN with status "0".
Connection id "0HL9BC18TNP2C" stopped.
Connection id "0HL9BC18TNP2D" completed keep alive response.
Request finished in 175.3974ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP2D" received FIN.
Connection id "0HL9BC18TNP2D" disconnecting.
Connection id "0HL9BC18TNP2D" sending FIN.
Connection id "0HL9BC18TNP2D" sent FIN with status "0".
Connection id "0HL9BC18TNP2D" stopped.
Connection id "0HL9BC18TNP27" received FIN.
Connection id "0HL9BC18TNP27" completed keep alive response.
Request finished in 171.6836ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP27" disconnecting.
Connection id "0HL9BC18TNP27" sending FIN.
Connection id "0HL9BC18TNP27" sent FIN with status "0".
Connection id "0HL9BC18TNP27" stopped.
Connection id "0HL9BC18TNP26" completed keep alive response.
Connection id "0HL9BC18TNP26" received FIN.
Request finished in 179.5263ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP26" disconnecting.
Connection id "0HL9BC18TNP29" completed keep alive response.
Request finished in 189.1427ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP2B" completed keep alive response.
Request finished in 179.8384ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP26" sending FIN.
Connection id "0HL9BC18TNP2E" completed keep alive response.
Connection id "0HL9BC18TNP2E" received FIN.
Request finished in 187.7259ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP2B" received FIN.
Connection id "0HL9BC18TNP29" received FIN.
Connection id "0HL9BC18TNP2B" disconnecting.
Connection id "0HL9BC18TNP2E" disconnecting.
Connection id "0HL9BC18TNP29" disconnecting.
Connection id "0HL9BC18TNP26" sent FIN with status "0".
Connection id "0HL9BC18TNP26" stopped.
Connection id "0HL9BC18TNP2B" sending FIN.
Connection id "0HL9BC18TNP2E" sending FIN.
Connection id "0HL9BC18TNP29" sending FIN.
Connection id "0HL9BC18TNP2E" sent FIN with status "0".
Connection id "0HL9BC18TNP2E" stopped.
Connection id "0HL9BC18TNP2B" sent FIN with status "0".
Connection id "0HL9BC18TNP2B" stopped.
Connection id "0HL9BC18TNP29" sent FIN with status "0".
Connection id "0HL9BC18TNP29" stopped.
Connection id "0HL9BC18TNP28" completed keep alive response.
Request finished in 190.027ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP28" received FIN.
Connection id "0HL9BC18TNP28" disconnecting.
Connection id "0HL9BC18TNP28" sending FIN.
Connection id "0HL9BC18TNP28" sent FIN with status "0".
Connection id "0HL9BC18TNP28" stopped.
Connection id "0HL9BC18TNP2A" received FIN.
Connection id "0HL9BC18TNP2A" completed keep alive response.
Request finished in 209.3495ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP2A" disconnecting.
Connection id "0HL9BC18TNP2A" sending FIN.
Connection id "0HL9BC18TNP2A" sent FIN with status "0".
Connection id "0HL9BC18TNP2A" stopped.
Connection id "0HL9BC18TNP25" completed keep alive response.
Request finished in 223.5798ms 200 application/json; charset=utf-8
Connection id "0HL9BC18TNP25" received FIN.
Connection id "0HL9BC18TNP25" disconnecting.
Connection id "0HL9BC18TNP25" sending FIN.
Connection id "0HL9BC18TNP25" sent FIN with status "0".
Connection id "0HL9BC18TNP25" stopped.

Upvotes: 0

Views: 2436

Answers (1)

Chris Pratt
Chris Pratt

Reputation: 239440

Async != parallel. Async does one thing and one thing only, it allows the thread to be returned to the pool when it is idle, so if can do other work instead of sitting idle. Period. That is all. When you await an asynchronous task, you code does not magically move on and keep processing. It "waits" (hence await) for the work to be completed.

If you do want to run a bunch of asynchronous tasks at the same time, you can use Task.WhenAll:

var tasks = new Task[]
{
    DoFirstAsync(),
    DoSecondAsync(),
    DoThirdAsync()
};
await Task.WhenAll(tasks);

This essentially just creates a Task that waits on all the other Tasks to complete, so you can await this instead.

Upvotes: 1

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