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Rob
Rob

Reputation: 7216

Thread start in Form1() crashing program on Windows Server 2008

Hey guys, I'm getting a really strange error. I have a program that needs to run a thread on startup, and for some reason when I do myThread.Start() in Form1() it will crash with "program is not working" (But only on Windows Server, not on my local machine!). However, if I put the same code under button1_Start() it works no problem. What gives?

Any ideas? Thank you.

EDIT A little extra information: In my thread I have a line of code that uses invoke

Invoke(new Action(() => richTextBox1.AppendText(string.Format("Updating {0}..\n", DateTime.Now))));

And for some reason the crashing goes away after I make the thread sleep for 2 seconds before it starts executing. Am I using the right method to execute code on the app startup?

Upvotes: 1

Views: 594

Answers (2)

Marino Šimić
Marino Šimić

Reputation: 7340

In our company we had the same symptom on an application that spawned a bitmap async loading that used COM - only on W2008.

The problem turned out to be:

  • we used a COM object from that thread (which was STA)
  • only on W2008 initialization of the object could not complete in time
  • thread started working before the COM was ready and getting error

I don't know why only on W2008, but our hack was to move the start of the thread from the constructor to the actual point where the thread work was needed.

Upvotes: 0

Lasse V. Karlsen
Lasse V. Karlsen

Reputation: 391634

Note, this is a guess, you haven't given nearly enough information in your question to give you any definitive answers.

I doubt it has anything to do with Windows Server 2008, but probably more with the fact that the server has more CPU cores and/or a faster processor than your development machine.

If you, in the thread tries to either access the form through a variable, or you try to invoke back to the thread that owns the form, you will crash on a fast computer.

Why?

In the first case, the variable has not yet been set. The following code:

var fm = new Form1();

here, fm will not be set before the constructor has returned. If your thread has already tried to access the form through fm, that variable is null.

In the second case, the constructor is not responsible for showing the form, that happens afterwards. Many controls postpone actually allocating a handle until they are asked to draw themselves, and thus if the thread tries to do stuff to a control before that, it will crash.

You should instead start your thread from Form_Load.

Upvotes: 2

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