Fixing slow initial load for IIS

Question

IIS has an annoying feature for low traffic websites where it recycles unused worker processes  causing the first user to the site after some time to get an extremely long delay  30  seconds    I ve been looking for a solution to the problem and I ve found these potential solutions   A  Use the Application Initialization plugin  B  Use Auto-Start with  NET 4  C  Disable the idle-timeout  under IIS Reset   D  Precompile the site  I m wondering which of these is preferred  and more importantly  why are there so many solutions to the same problem   My guess is they aren t  and I m just not understanding something correctly    Edit  Performing C seems to be enough to keep my site warmed up  but I ve discovered that the real root of my site s slowness has to do with Entity Framework  which I can t seem to figure out why it s going cold  See this question  which unfortunately hasn t been answered yet has been answered   I eventually just had to make a warm up script to hit my site occasionally to make sure it stayed speedy

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I was getting a consistent 15 second delay on the first request after 4 minutes of inactivity  My problem was that my app was using Windows Integrated Authentication to SQL Server and the service profile was in a different domain than the server  This caused a cross-domain authentication from IIS to SQL upon app initialization - and this was the real source of my delay  I changed to using a SQL login instead of windows authentication  The delay was immediately gone  I still have all the app initialization settings in place to help improve performance but they may have not been needed at all in my case

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Options A  B and D seem to be in the same category since they only influence the initial start time  they do warmup of the website like compilation and loading of libraries in memory   Using C  setting the idle timeout  should be enough so that subsequent requests to the server are served fast  restarting the app pool takes quite some time - in the order of seconds    As far as I know  the timeout exists to save memory that other websites running in parallel on that machine might need  The price being that one time slow load time   Besides the fact that the app pool gets shutdown in case of user inactivity  the app pool will also recycle by default every 1740 minutes  29 hours    From technet      Internet Information Services  IIS  application pools can be   periodically recycled to avoid unstable states that can lead to   application crashes  hangs  or memory leaks    As long as app pool recycling is left on  it should be enough  But if you really want top notch performance for most components  you should also use something like the Application Initialization Module you mentioned

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See this article for tips on how to help performance issues   This includes both performance issues related to starting up  under the  quot cold start quot  section   Most of this will matter no matter what type of server you are using  locally or in production  https   blogs msdn microsoft com b mcsuksoldev 2011 01 19 common-performance-issues-on-asp-net-web-sites   If the application deserializes anything from XML  and that includes web services     make sure SGEN is run against all binaries involved in deseriaization and place the resulting DLLs in the Global Assembly Cache  GAC   This precompiles all the serialization objects used by the assemblies SGEN was run against and caches them in the resulting DLL  This can give huge time savings on the first deserialization  loading  of config files from disk and initial calls to web services  http   msdn microsoft com en-us library bk3w6240 VS 80  aspx   If any IIS servers do not have outgoing access to the internet  turn off Certificate Revocation List  CRL  checking for Authenticode binaries by adding generatePublisherEvidence    false    into machine config  Otherwise every worker processes can hang for over 20 seconds during start-up while it times out trying to connect to the internet to obtain a CRL list  http   blogs msdn com amolravande archive 2008 07 20 startup-performance-disable-the-generatepublisherevidence-property aspx   http   msdn microsoft com en-us library bb629393 aspx   Consider using NGEN on all assemblies  However without careful use this doesn   t give much of a performance gain  This is because the base load addresses of all the binaries that are loaded by each process must be carefully set at build time to not overlap  If the binaries have to be rebased when they are loaded because of address clashes  almost all the performance gains of using NGEN will be lost  http   msdn microsoft com en-us magazine cc163610 aspx

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Web Hosting Challenge  You have to remember that none of the machine configuration options are available if you are hosted on a shared server as many of us  smaller companies and individuals  are    ASP NET MVC Overhead  My site takes at least 30 seconds when it hasn t been hit in over 20 minutes  and the web app has been stopped    It is terrible    Another Way to Test Performance  There s another way to test if it is your ASP NET MVC start up or something else   Drop a normal HTML page on your site where you can hit it directly  If the problem is related to ASP NET MVC start up then the HTML page will render almost immediately even when the web app hasn t been started  That s how I first recognized that the problem was in the ASP NET MVC startup  I loaded an HTML page at any time and it would load blazing fast   Then  after hitting that HTML page I d hit one of my ASP NET MVC URLs and I d get the Chrome message  Waiting for raddev us        Another Test With Helpful Script  After that I wrote a LINQPad  check out http   linqpad net for more  script that would hit my web site every 8 minutes  less than the time for the app to unload -- which should be 20 minutes  and I let it run for hours     While the script was running I hit my web site and every time my site came up blazingly fast   This gives me a good idea that most likely the slowness I was experiencing was because of ASP NET MVC startup times   Get LinqPad and you can run the following script -- just change the URL to your own and let it run and you can test this easily  Good luck   NOTE  In LinqPad you ll need to press F4 and add a reference to System Net to add the library which will retrieve your page    ALSO   make sure you change the String URL variable to point at a URL that will load a route from your ASP NET MVC site so the engine will run   System Timers Timer webKeepAlive   new System Timers Timer    Int64 counter   0  void Main         webKeepAlive Interval   5000      webKeepAlive Elapsed    WebKeepAlive Elapsed      webKeepAlive Start       private void WebKeepAlive Elapsed object sender  System Timers ElapsedEventArgs e        webKeepAlive Stop        try                  ONLY the first time it retrieves the content it will print the string         String finalHtml   GetWebContent            if  counter  lt  1                        Console WriteLine finalHtml                     counter              finally               webKeepAlive Interval   480000     every 8 minutes         webKeepAlive Start             public String GetWebContent         try           String URL    http   YOURURL COM       WebRequest request   WebRequest Create URL       WebResponse response   request GetResponse        Stream data   response GetResponseStream        string html   String Empty      using  StreamReader sr   new StreamReader data                 html   sr ReadToEnd              Console WriteLine  String Format   0    success  DateTime Now        return html            catch  Exception ex                Console WriteLine  String Format   0  -- GetWebContent      1   DateTime Now ex Message            return  fail

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I d use B because that in conjunction with worker process recycling means there d only be a delay while it s recycling  This avoids the delay normally associated with initialization in response to the first request after idle  You also get to keep the benefits of recycling

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A good option to ping the site on a schedule is to use Microsoft Flow  which is free for up to 750  runs  per month  It is very easy to create a Flow that hits your site every hour to keep it warm  You can even work around their limit of 750 by creating a single flow with delays separating multiple hits of your site   https   flow microsoft com

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Writing a ping service script to hit your idle website is rather a best way to go because you will have a complete control  Other options that you have mentioned would be available if you have leased a dedicated hosting box    In a shared hosting space  warmup scripts are the best first level defense  self help is the best help   Here is an article which shares an idea on how to do it from your own web application

[asp.net] Fixing slow initial load for IIS

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