async void Handle(EventArgs e)
{
    await _semaphore.WaitAsync();

    var thread = new Thread(() =>
    {
        Process(e);
        _semaphore.Release();
        _channel.BasicAck(....);
    });
    thread.Start();
}

var workerBlock = new ActionBlock<EventArgs>(
    // Process event
    e => Process(e),
    // Specify a maximum degree of parallelism.
    new ExecutionDataflowBlockOptions
    {
        MaxDegreeOfParallelism = InitialCount
    });
var bufferBlock = new BufferBlock();
// link the blocks for automatically propagading the messages
bufferBlock.LinkTo(workerBlock);

// asynchronously send the message
await bufferBlock.SendAsync(...);
// synchronously send the message
bufferBlock.Post(...);

bufferBlock.LinkTo(cpuWorkerBlock, e => e is CpuEventArgs);
bufferBlock.LinkTo(networkWorkerBlock, e => e is NetworkEventArgs);
bufferBlock.LinkTo(diskWorkerBlock, e => e is DiskEventArgs);

bufferBlock.LinkTo(DataflowBlock.NullTarget<EventArgs>);