uncaught exception handlers

[Derek Bartram]

I've just done some googling on the subject (and confirmed via a lecturer from Uni).... 1) There is a performance hit running code inside a try...catch block but it's negligable 2) There is a BIG performance hit when an exception occurs So, 3) Use try...catch for only catching untestable errors and not controlling programming flow. http://www.javaworld.com/javaworld/javaqa/2001-07/04-qa-0727-try.html[^] http://aspadvice.com/blogs/name/archive/2008/01/18/Try-Catch-Performance-in-CSharp_3A00_-A-Simple-Test-Response.aspx[^]

[Derek Bartram]

Yes.... run the code with catch (Exception err) and output err.GetType() somehow (Console.WriteLine will do). You'll then know the type of the exception raised so you can go back and modify catch (Exception err) to the specific type.

[George_George]

Thanks Derek, Cool!! Your 1st link is Java... :-) I am interested in your 2nd link. But confused what means "catching untestable errors" and "not controlling programming flow"? Could you show some samples please? regards, George

[George_George]

Thanks Derek, I agree with your exception handling approach. Any answers or comments to my original question? :-) regards, George

[realJSOP]

For a console app, you could put try/catch around the guts of your main() function.

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001

[George_George]

Hi John, I think in this approach, we can only catch exception from main thread, right? (Suppose we create new threads from main methods, then we can not catch exception from other threads in main method?) regards, George

[PIEBALDconsult]

Derek Bartram wrote:

massive performance hit

Perhaps you haven't read this[^] yet.

[PIEBALDconsult]

Indeed, I always put a try/catch in the Main.

[Derek Bartram]

Thanks for the link, an interesting article. I probably didn't specify 'massive' which didn't help; I meant relative to performing an if test to prevent the exception.

[N a v a n e e t h]

George_George wrote:

Windows Forms application?

Yes. Also you can wrap the main() method in try catch blocks. So it can handle all exceptions.

All C# applications should call Application.Quit(); in the beginning to avoid any .NET problems.- Unclyclopedia How to use google | Ask smart questions

[George_George]

No, N a v a n e e t h. Not catch all exceptions, you can not catch exception from other threads? Right? regards, George

[George_George]

Thanks PIEBALDconsult, Good reference. :-) regards, George

[George_George]

Thanks Derek, What do you mean "didn't specify 'massive' which didn't help" and "relative to performing an if test to prevent the exception"? Could you show more description or some pseudo code about your approach please? regards, George

[N a v a n e e t h]

George_George wrote:

you can not catch exception from other threads? Right?

Yes. You are right. I missed that. Hook AppDomain.UnhandledException which handles all exception other than the ones I specified in my first message.

All C# applications should call Application.Quit(); in the beginning to avoid any .NET problems.- Unclyclopedia How to use google | Ask smart questions

[George_George]

You mean "Also exceptions occurring in unmanaged resources won't be handled too" will not be handled? regards, George

[MidwestLimey]

Derek Bartram wrote:

Does anyone know if a try...catch block affects the performance of the try block code? I know it has a performance hit on hitting the block, but I wonder if it has a continuing effect beyond that.

I once worked on a project where the Project Lead insisted on try catch blocks in every bloody method. I did some performance testing and could determine definitive costs with the setup and teardown of the block, but was unable to measure any discernable difference to the code internally. However the code was entirely managed, perhaps wrapping unmanaged code has other implications.

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I'm largely language agnostic

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After a while they all bug me :doh:

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[Spacix One]

If you wanted to go that far you can catch errors in your thread method also... Are you looking for on error resume next type functionally? If so might be better to use VB.NET as C# doesn't allow for that coding horror :) You need to remember the following: Using exceptions to control programming logic is is the same as having car insurance to repair the damange after rolling off a cliff instead of setting the parking break to prevent it from rolling away.

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-Spacix All your skynet questions[^] belong to solved

[N a v a n e e t h]

George_George wrote:

"Also exceptions occurring in unmanaged resources won't be handled too"

Yes. It won't be handled. Because it runs out of CLR.

All C# applications should call Application.Quit(); in the beginning to avoid any .NET problems.- Unclyclopedia How to use google | Ask smart questions

[George_George]

Thanks Spacix, 1.

Spacix One wrote:

If you wanted to go that far you can catch errors in your thread method also...

So, no means to catch exception from another thread, right? :-) 2.

Spacix One wrote:

on error resume next type functionally? If so might be better to use VB.NET as C# doesn't allow for that coding horror

Sorry, I have no experience in VB. Could you say something alternative to describe your ideas please? I do not quite understand, especially what do you mean "on error resume next type functionally". :-) regards, George

[George_George]

Thanks N a v a n e e t h, 1. Seems UnhandledException is the only approach to handle exception from other threads, and I have tried even ProcessExit does not work. Here is my code to test. Could you review whether my code and my points are correct? :-) 2. After the handler for UnhandledException is executed, process is always terminated?

using System;
using System.Threading;

namespace DelegateThread
{
class Test
{
private static void Method2 (object input)
{
Console.WriteLine("Method1 is throwing exception");
throw new ApplicationException("**** oops ****");
}

    private static void Method1()
    {
        Console.WriteLine("Method1 is throwing exception");
        throw new ApplicationException("\*\*\*\* oops \*\*\*\*");
    }

    private static void Handler1 (object sender, EventArgs e)
    {
        Console.WriteLine ("I am here");
    }

    private static void Handler3(object sender, EventArgs e)
    {
        Console.WriteLine("I am here");
    }

    delegate void Method1Delegate();

    static void Main(string\[\] args)
    {
        Console.WriteLine("We first use a thread");

        AppDomain.CurrentDomain.ProcessExit += new EventHandler (Test.Handler1);
        AppDomain.CurrentDomain.UnhandledException +=new UnhandledExceptionEventHandler(Test.Handler3);
        
        Thread aThread
            = new Thread(new ThreadStart(Method1));
        aThread.Start();
        


        Thread.Sleep(5000);

        Console.WriteLine("Survived exception");

        return;

    } // main
}

}

regards, George