Hi

I have two threads, one thread processes a queue and the other thread adds stuff into the queue.

1. I want to put the queue processing thread to sleep when its finished processing the queue
2. I want to have the 2nd thread tell it to wake up when it has added an item to the queue

However these functions call System.Threading.SynchronizationLockException: Object synchronization method was called from an unsynchronized block of code on the Monitor.PulseAll(waiting); call, because I havent syncronized the function with the waiting object. [which I dont want to do, i want to be able to process while adding items to the queue]. How can I achieve this?

Queue<object> items = new Queue<object>();
object waiting = new object();

1st Thread

public void ProcessQueue()
{
 while (true)
 {
   if (items.Count == 0)
     Monitor.Wait(waiting);

    object real = null;
    lock(items) {
    object item = items.Dequeue();
    real = item;
    }
    if(real == null)
        continue;
    .. bla bla bla
 } 
}

2nd Thread involves

public void AddItem(object o)
{
 ... bla bla bla
 lock(items)
 {
 items.Enqueue(o);
 }
 Monitor.PulseAll(waiting);
}