Idle worker process page out a second scalability

This preview shows page 168 - 169 out of 242 pages.

The Configuration Editor configures Dynamic Site Activation. Idle Worker Process Page-out A second scalability issue that can be experienced on IIS servers hosting large numbers of sites has to do with cold requests. A cold request is a request that comes for a worker process that has not yet been started. The cold request has to wait for IIS to initialize, for the appropriate framework (for example, .NET or PHP) to initialize, for the associated site to initialize, and so on. As a result, the response time to cold requests with previous versions of IIS sometimes left something to be desired. This issue was partly addressed with IIS 8 in Windows Server 2012 where static sites responded much more quickly (typically a few hundred milliseconds) to cold requests than for IIS 7 in Windows Server 2008 R2. However, there was only a small performance improvement in IIS 8 for dynamic sites with managed code, with such sites typically taking several seconds to start in response to cold requests, largely because of the time needed to load the application framework needed by the site. From the perspective of the hoster’s customers, however, taking several seconds to launch their LOB web application can be viewed negatively as unacceptable and poor performance. To improve the start time for dynamic sites in response to cold requests, a module called Application Initialization, was included in IIS 8 in Windows Server 2012 that allowed the administrator to preload the application framework needed for a dynamic site so that the site could respond to a cold request in a few hundred milliseconds instead of several seconds. However, this module is not useful for hosters because such preloaded application
Image of page 168

Subscribe to view the full document.

Idle Worker Process Page-out CHAPTER 8 157 frameworks consume additional memory for each site configured to use them. Since the IIS servers of a hoster are typically hosting thousands of sites and are usually memory-bound (assume at least 100 MB needed per dynamic site), such preloading application frameworks for all sites hosted on a server just wasn’t feasible. IIS can partly address this problem by killing idle worker processes after a default of 20 minutes of inactivity, and WAS can halve this time interval if it determines that memory pressure has reached 80 percent on the server. IIS 8.5 in Windows Server 2012 R2 now takes a different perspective on how to address the problem of cold request delays for dynamic sites. A new feature called Idle Worker Process Page-out, saves memory by allowing an idle worker process to be paged to disk so that the worker process is removed from memory. The page-out feature can be made to perform even better by utilizing a solid state disk (SSD) for the paging file of an IIS server. The result is that memory pressure can now be greatly reduced for servers hosting thousands of dynamic sites and the response time to cold requests for these sites can be significantly improved.
Image of page 169
You've reached the end of this preview.
  • Spring '16

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern