Application errors fixed with an IIS reset/Memory hanging

Posted on 2005-04-27
Last Modified: 2008-02-01
Our project recently upgraded our .NET Web Application to a new server. The old server was Windows 2000 using IIS 5.0, dual processor, using an Oracle 8i database on a separate server and .NET 1.1. The new server is Windows 2003 using IIS 6.0, quad processor, using an Oracle 9i database on a separate server and .NET 1.1. Both connect to Oracle using the ODP.NET v driver. All software is updated regularly to include the latest service packs and/or patches. This web server is also running several other small web applications. Since we have migrated to the new environment we have experienced multiple issues and performance problems and we are trying to pull apart each piece of technology being used to identify the culprit(s).

When we moved to IIS 6.0, we kept all of the default settings, including memory. Our software consists of over 550 pages, many which make extensive use of the database using extremely complex queries and logic. Our pages consist of about 1/3 selection pages, 1/3 reports and 1/3 update screens. The reports can return large datasets, sometimes up to 4000 records.

We are periodically experiencing TNS errors on some of our application pages. First, we logged a help call with Oracle and after several dump files and conversations they determined the problem was not from within the database but was occuring in the calling application. Next, we logged a help call with Microsoft. It seems the way we were connecting to the database was not using Best Practices, although wasn't incorrect. Either way, we are currently in the process of recoding all of our pages to use Microsoft's best practices.

What we are experiencing now is that a particular page will throw a TNS error. Once the page throws the error, the page becomes unuseable until we either a) recode the page or b) reset IIS. What we see though is that we only see this TNS error on one particular page over and over again. Once we recode that page, a new page which had been operating fine before now gets a TNS error.

Additionally, there are several other web applications being run on this web server that are unaffected by the transition.

Why would the software behave differently in our new environment and why would the error seem to randomly appear on a particular page? Also, is there a less invasive method to clearing memory other than resetting IIS?
Question by:MiddletownRI
    LVL 6

    Accepted Solution

    Hey Middletown....

    Man that sucks...I feel for you. First off your last question, doing a Stop then Start on the website may be a less invasive way to restart the site or web app in question without having to bring all of IIS down.

    Secondly, the basic answer to your first question is that IIS5 and IIS6 process code differently... this site may help you as it addresses "isolation mode"...just go here and read about Isolation Mode (about half way down) As far as why it would be a seemingly random appearing error, well, it could be a number of things, such as subtle differences in the way the page is being called and processed by the 1.1 framework.

    I hope that "IIS5 Isolation mode" applies to what you're doing.

    I almost hesitate to mention this, but there is a beta version of .NET 2.0 available...if you have a NON PRODUCTION SERVER that you want to test it on to see if it improves your app, then by all means go ahead...but personally, I would NOT use it on a production server (it could be difficult to revert back to 1.1).

    Best of luck to you!


    Author Comment


    Thanks for your empathy! It does indeed suck.

    We will test doing a Stop/Start on the website as opposed to an IIS reset to see if it will clear the memory. Thanks for the suggestion.

    As far as Isolation Modes, this is something we have already researched and tested, but it didn't appear to make a difference.

    We are very anxious for .Net 2002 and VS.Net 2005, but we won't be able to use these products until they are officially released. We can't use any software still in BETA, unfortunately.

    Thanks again for your response,

    Author Comment

    Even though you didn't answer the biggest question related to the TNS errors, I felt it appropriate for you to receive the points since you made an honest and sincere effort to help with at least some of our problems.
    Thanks again for your efforts,

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