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.NET Forum / ASP.NET / General / August 2007Sessions timing out quickly despite very high timeout set in web.config
Hello, We have a large asp.net writtin in VB.Net 2003, and for some reason the sessions have started timing out very quickly, like 5-10 minutes in some cases. In web.config we have the SessionState timeout set at 720 minutes, but this doesn't seem to help. What we're seeing is users working in the system just fine, then they'll get the following error when the application tries to reference the session: -[Begin Snippet]------------------------------------- Server Error in '/' Application. Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [NullReferenceException: Object reference not set to an instance of an object.] Sigma.DetailsReport.RetrieveData() in C:\Inetpub\wwwroot\App\Loan\Details.aspx.vb:107 Sigma.DetailsReport.Page_Load(Object sender, EventArgs e) in C:\Inetpub\wwwroot\App\Loan\Details.aspx.vb:71 System.Web.UI.Control.OnLoad(EventArgs e) +67 System.Web.UI.Control.LoadRecursive() +35 System.Web.UI.Page.ProcessRequestMain() +750 Version Information: Microsoft .NET Framework Version:1.1.4322.2300; ASP.NET Version:1.1.4322.2300 -[End Snippet]------------------------------------- When reviewing the code from the trace, it always is something that references something in the Session, and my assumption is the session has expired causing a null to be returned. I'm fairly new to the world of VB, but being a seasoned web coder of other languages I'm not sure exactly what to try next. I'm working on adding code to detect the timeout and return something other then a .Net error, but this still won't help the fact that our sessions are timing out in a matter of minutes when they shouldn't be. Thanks in advance for any advise or suggestions on this -- Alex It might be the Session is expired, or it could just be that the object attempting to be referenced is null ("Nothing in VB.NET"). I see 2 things you might do to help improve things: 1) Set Option Explicit and Option Strict to "on". This at least attempts to put you on a level playing field with us C# folks. 2) Wire up your app with unhandled exception handling and logging in your Application_Error handler in global.asax. -- Peter Recursion: see Recursion site: http://www.eggheadcafe.com unBlog: http://petesbloggerama.blogspot.com BlogMetaFinder: http://www.blogmetafinder.com > Hello, > [quoted text clipped - 50 lines] > > Alex check the event log (on the iis box) for recycle events. these will happen if your site uses too much memory (large sessions, memory leaks, etc) or has hanging threads. if your app is not written to gracefully handle a lost session, then you should not use inproc sessions. -- bruce (sqlwork.com) > Hello, > [quoted text clipped - 50 lines] > > Alex Hi Bruce, Actually I hadn't thought about checking the server event log... I did so and noticed several errors like this: Event Type: Information Event Source: W3SVC Event Category: None Event ID: 1117 Date: 8/24/2007 Time: 12:43:20 PM User: N/A Computer: WEBSERVER01 Description: A worker process with process id of '3120' serving application pool 'USPool' has requested a recycle because it reached its private bytes memory limit. Then about a minute later: Event Type: Warning Event Source: W3SVC Event Category: None Event ID: 1013 Date: 8/24/2007 Time: 12:44:51 PM User: N/A Computer: WEBSERVER01 Description: A process serving application pool 'USPool' exceeded time limits during shut down. The process id was '3120'. ... I take it this would cause sessions to be dropped? If so, that's definitely puzzle solved as we've had several times where everyone is dropped at the same time. This application was written by a programmer who's no longer here, and being somewhat new to the world of ASP.Net I'm trying to fix the problems as they come up. I'm educating myself on the way ASP.Net does sessions, and I am finding it's a tricky beast to work with.. Any suggestions on alternatives to using inproc? Thanks again, and take care -- Alex > check the event log (on the iis box) for recycle events. these will happen > if your site uses too much memory (large sessions, memory leaks, etc) or [quoted text clipped - 60 lines] >> >> Alex Yea, that is the cause, Process recycled everything flushed, all sessions gone, Application initializes fresh new. Not sure what exactly a problem but looks like memory leak of some kind George. > Hi Bruce, > [quoted text clipped - 104 lines] >>> >>> Alex Thanks... This is definitely what's causing the problem. We just got calls from users getting kicked out, and after checking the event logs yet another recycle. Now the research to find what's going on. Thanks again for the info, once we figure out why the pool is recycling, our problems should be solved. Take care -- Alex > Yea, that is the cause, > Process recycled everything flushed, all sessions gone, Application [quoted text clipped - 111 lines] >>>> >>>> Alex Besidess running Scott Guthrie's code to pinpoint the reason for the recycling of the apps, you should look into using a different method of maintaining state for your apps. Maintaining session state with either SQL Server or State Server will preserve session values across application recycles. Juan T. Llibre, asp.net MVP asp.net faq : http://asp.net.do/faq/ foros de asp.net, en español : http://asp.net.do/foros/ ====================================== > Thanks... This is definitely what's causing the problem. We just got calls from users getting kicked out, and after > checking the event logs yet another recycle. Now the research to find what's going on. [quoted text clipped - 98 lines] >>>>> >>>>> Alex You might want to look into what is causing your applications to recycle. An easy way to do this is to implement Scott Guthrie's tips for logging ASP.NET application shutdown events : http://weblogs.asp.net/scottgu/archive/2005/12/14/433194.aspx By using this diagnostics tool, you can figure out why and when ASP.NET restarts application domains. Juan T. Llibre, asp.net MVP asp.net faq : http://asp.net.do/faq/ foros de asp.net, en español : http://asp.net.do/foros/ ====================================== > Hello, > [quoted text clipped - 39 lines] > > Alex Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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