StringBuilder.ToString() throw an 'Index out of range' Exception

Question

I would really appreciate someone help me resolving the following issue:

I am getting now and then the following exception:

Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: chunkLength

on stringBuilder.ToString().

What is strange is if I put stringBuilder.ToString() in the watch, it works perfectly.

Is it possible that your StringBuilder is also being used by another thread? — Thomas Levesque, Sep 28 '12 at 18:24
Could you provide the snippit that causes the exception including how string builder is built up? — deepee1, Sep 28 '12 at 18:25
The stringBuilder.AppendLine is called on an events. It is then displayed on the screen on a different thread. — Gerhard Powell, Sep 28 '12 at 18:29
@GerhardPowell, that's probably the cause of your problem. StringBuilder is not thread-safe, it shouldn't be used concurrently from different threads. If you need to display it from a different thread, pass the result of ToString to the other thread, not the StringBuilder itself. — Thomas Levesque, Sep 28 '12 at 18:35

score 50 · Accepted Answer · answered Sep 28 '12 at 18:36

50

Look like it is a multi thread issue. I locked the thread to prevent multi access to the stringBuilder at the same time.

public void AddString(string s)
{
  lock(this.LockObject)
  {
     StringBuilder.AppendLine(s);
  }
}

answered Sep 28 '12 at 18:36

Gerhard Powell

1 Answers1