My application spawns loads of different small worker threads via `ThreadPool.QueueUserWorkItem` which I keep track of via multiple `ManualResetEvent` instances. I use the `WaitHandle.WaitAll` method to block my application from closing until these threads have completed.

I have never had any issues before, however, as my application is coming under more load i.e. more threads being created, I am now beginning to get this exception:

`WaitHandles must be less than or equal to 64 - missing documentation`

What is the best alternative solution to this?

&lt;b&gt; Code Snippet &lt;/b&gt;

    List&lt;AutoResetEvent&gt; events = new List&lt;AutoResetEvent&gt;();

    // multiple instances of...
    var evt = new AutoResetEvent(false);
    events.Add(evt);
    ThreadPool.QueueUserWorkItem(delegate
    {
        // do work
        evt.Set();
    });

    ...
    WaitHandle.WaitAll(events.ToArray());

&lt;b&gt; Workaround &lt;/b&gt;

    int threadCount = 0;
    ManualResetEvent finished = new ManualResetEvent(false);

    ...
    Interlocked.Increment(ref threadCount);
    ThreadPool.QueueUserWorkItem(delegate
    {
        try
        {
             // do work
        }
        finally
        {
            if (Interlocked.Decrement(ref threadCount) == 0)
            {
                 finished.Set();
            }
        }
    });

    ...
    finished.WaitOne();

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Workaround for the WaitHandle.WaitAll 64 handle limit?