[Python][Web Apps] web app and fastcgi restarts RRS feed

  • Question

  • I have a client with Python app and very high performance requirements. They are testing Azure Web Apps for their app. They will probably use Python on Web Apps (S3) with autoscaling + SQL Azure. They (and me with them) are testing their test app with up to 200 requests per second. We have find out how to optimize it to handle such a traffic with autoscaling and SQL Azure - this part is OK.
    But there is a very big problem with Python on Web Apps. The FCGI server is restarting application for time to time. Of course we have Always-ON turned ON and configured application pool recycling:

    We are load testing this app with 100 concurrent connections (virtual users) with +1/s traffic growth. We have tested 4 different configurations:

    1) F1 Server, AlwaysOn disabled (cannot turn on on F1), kudu - without application pool optimization
    2) S3 Server, AlwaysOn - disabled, kudu - without application pool optimization
    3) S3 Server, AlwaysOn - enabled, kudu - without application pool optimization
    4) S3 Server, AlwaysOn - enabled, kudu - with application pool optimization

    We have tested how many restarts our test application will have during the test:

    1) 5 restarts
    2) 21 restarts
    3) 16 restarts
    4) 11 restarts

    As You can see, Always-ON + application pool optimization is working but... it is still restarting. What is going on? Why it is restarting? Is it IIS-related problem? On Linux machines there is no problem like this.

    Wednesday, January 13, 2016 10:14 AM


  • I have resolved this issue. WIll write some blog later about that. There is completly NO documentation about how to handle Python apps properly on Web Apps...
    • Marked as answer by smereczynski Thursday, January 21, 2016 8:24 PM
    Thursday, January 14, 2016 11:14 PM

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