UnboundedChannel.cs

if (blockedReader != null)
{
    // Complete the reader.  It's possible the reader was canceled, in which
    // case we loop around to try everything again.
    if (blockedReader.TrySetResult(item))
    {
        return true;
    }
}
else
{
    // Wake up all of the waiters.  Since we've released the lock, it's possible
    // we could cause some spurious wake-ups here, if we tell a waiter there's
    // something available but all data has already been removed.  It's a benign
    // race condition, though, as consumers already need to account for such things.
    ChannelUtilities.WakeUpWaiters(ref waitingReadersTail, result: true);
    return true;
}