C# – ASP.NET exception “Thread was being aborted” causes method to exit

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In the code below, sometimes someFunctionCall() generates an exception:

Thread was being aborted.

How come the code in code Block B never runs? Does ASP.NET start a new thread for each method call? I was suprised to see that when this exception happens the code in Block B never runs, the method returns, and my application keeps running. Can someone please explain this?

public void method()
{
     // CODE BLOCK A
     //...    

     try 
     {
         someFunctionCall(); // this call is generating thread abort exception
     }
     catch(Exception ex)
     {
         // log exception message
     }

    // CODE BLOCK B
    // ...    
}

Best Solution

This is a ThreadAbortException; it's a special exception that is automatically rethrown at the end of every catch block, unless you call Thread.ResetAbort().

ASP .Net methods like Response.End or Response.Redirect (unless you pass false) throw this exception to end processing of the current page; your someFunctionCall() is probably calling one of those methods.

ASP .Net itself handles this exception and calls ResetAbort to continue processing.

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C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

C# – “Thread was being aborted” exception whilst displaying dialog

Do not use Thread.Abort. This method is reserved for when the .NET runtime needs to forcibly kill threads in order to unload your program.

You can only "safely" use this if you're about to unload an AppDomain and want to get rid of threads running in it first.

To get rid of a thread, write it in cooperative mode. This means that the thread should periodically check some kind of flag, and if the flag is set, exit normally out of the thread method. To "kill" the thread, simply set the flag and wait for the thread to exit.

You can use an Event-object or a simple boolean variable for this flag.

But do not use Thread.Abort.

Best Solution

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C# – “Thread was being aborted” exception whilst displaying dialog

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