C#

if (<code>Event </code>!= null){
      <code>Event</code>(<code>this</code>, <code>e</code>);    
   }

lock(this){
if (<code>Event </code>!= null){
      <code>Event</code>(this, e);    
   }
}

lock(<code>Event</code>){
if (<code>Event </code>!= null){
      <code>Event</code>(this, e);    
   }
}

lock(this) {
  if (Event != null) {      
    Event(this, e);
  }
}

public class ThreadTest
{
  private ArrayList _events = new ArrayList();

  public event EventHandler MyEvent
  {
    add { lock (this) { _events.Add(value); } }
    remove { lock (this) { _events.Remove(value); } }
  }

  public void Start()
  {
    // Same code as before
  }

  private void ThreadMethod()
  {
    while (true)
    {
      ArrayList clone;
      lock (this)
      {
        clone = (ArrayList)_events.Clone();
      }
      foreach (EventHandler e in clone)
      {
        e.DynamicInvoke(...);
      }
    }
  }
}

public void Call(A caller)
{
  object callerr = caller;
}