This document discusses improving server-side web performance in ASP.NET applications. It recommends using asynchronous programming to prevent blocking of request threads in IIS, which can cause poor performance and 503 errors. Specific techniques mentioned include using Async="true" in ASP.NET Web Forms pages, asynchronous controllers in MVC, and Comet/reverse AJAX for real-time updates without polling. A chat application demo is provided to illustrate an asynchronous Comet implementation in ASP.NET that provides better live updating than traditional AJAX techniques.

1. server-side web trackbrought to you by

2. Getting out of Sync with IISand Riding a COMET Richard Banks richard-banks.org @rbanks54TalkingShopDownUnder.com

3. Goal: Improve your Server Side Performance

4. WebForms,MVC &Comet

5. Client side Things we already know(hopefully!)

6. Fewer requests == more performance!

7. View State Is EVIL!!! 

8. CDN’s, css sprites, minification, YSLOW, etc, etc

9. Server side?

10. Minimal DB calls,Cache usage, AJAX, and so forth

11. But what if you’ve done all that already?!

12. What if you have “Hanging” Requests?

13. Poor performance with very little load?

14. Probably BLOCKingREQUEST THREADS

15. Some IIS Internals

16. IIS 6.0: 12request threads per CPUAlso IIS 7.0 in Classic pipeline mode

17. 20worker & 20 IO threads per CPU

18. No free threads?The request gets queuedPerfMon Counter:ASP.NET\Requests in Application Queue

19. Limit is 5000 requests. Over that? 503 errorsPerfMon Counter:ASP.NET\Requests Current

20. IIS 7.0 (Intg): 12 concurrent requests per CPUApplies to .NET 2.0

21. In .NET 4.0: 5000 per CPU!

22. MS says do same in ASP.NET 2.0. Add registry key or edit aspnet.configMaxConcurrentRequestsPerCPUHKLM\SOFTWARE\Microsoft\ASP.NET\2.0.50727

23. Note: App Pool Queue Length is 1000

24. Before messing with configs… Get Async!

25. Time For some Demofun!

26. ASP.NET Web Forms

27. Async=“true”in page directive.

28. REGISTERASYNCTASK and PageASYNCTASKhttp://msdn.microsoft.com/en-us/library/system.web.ui.pageasynctask.aspx

29. ASP.NET MVCAsyncControlers

30. Howz about USING that new ASYNC Keyword?!

31. Now for the new Hawtness!

32. COMET!Aka “Reverse AJAX”

33. Practical uses:Stock tickerSports scoresAuction biddingBus Service GPS updatesWarehouse movements & logisticsGoogle+Anything broadcasting events/msgs

34. Canonical Demo:Web Chat

35. Implement Via UpdatePanel?Ajax Request on Enter:No live update

36. Need to send full chat history each time

37. Uses Update Panel!AJAX && JSON(aka wOOtage!)Use a jssetTimeout() callOnly ask for messages after msgIdRegular polling to get messages

38. Long Polling or StREAMING(no, not web sockets)

39. Bayeux Protocolhttp://cometd.org/Dojo & Jquery Bindings

40. Lots of other Comet servers. I want TO USE IISIIS threading means no streaming support, only long polling.

41. CHAT Demo: AspComet(on Appharbor)http://chat.richard-banks.org

42. For better Comet go Threadless: Manos de Mono or Node.jsJust Remember Mordac will likely need bribing to deploy it

43. Faye is a Bayeaux server for Node.JShttp://faye.jcoglan.com/

44. ResourcesContention, poor performance, and deadlocks: http://support.microsoft.com/kb/821268ASP.NET Thread Usage on IIS 6.0 and IIS 7.0: http://blogs.msdn.com/b/tmarq/archive/2007/07/21/asp-net-thread-usage-on-iis-7-0-and-6-0.aspxImproving ASP.NET Performance: http://msdn.microsoft.com/en-us/library/ff647787.aspxPageAsyncTask: http://msdn.microsoft.com/en-us/library/system.web.ui.pageasynctask.aspxMVC Async Controllers: http://msdn.microsoft.com/en-us/library/ee728598.aspxShould DB Calls be Async? http://blogs.msdn.com/b/rickandy/archive/2009/11/14/should-my-database-calls-be-asynchronous.aspxAspComet: http://github.com/nmosafi/aspcometBayeux and Cometd: http://svn.cometd.com/trunk/bayeux/bayeux.htmlManos De Mono: http://github.com/jacksonh/manosNode.JS: http://nodejs.org/FAYE: http://faye.jcoglan.com/

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