Question

Is there a quick way to log that a thread is waiting for a lock when a thread arrives at a

lock(x)
{
  //do work on a collection

}

?

If thread 1 arrives at the lock, and there isn’t another thread in the block, there should be no log. Then if thread 2 arrives at the lock(x) and thread 1 is still in the block, there should be a log. The ideal solution would not require switching to a Mutex or Monitor add much complexity. If there’s a quick and easy way to do this using TPL, PLINQ, or RX that would be great.

Answer 1

You can de-sugar the lock statement and use Monitor.TryEnter to check if the lock can be acquired without waiting:

bool lockTaken = false;
var obj = x;
try
{
    Monitor.TryEnter(obj, ref lockTaken);
    if (!lockTaken)
    {
        Log();
        Monitor.Enter(obj, ref lockTaken);
    }
    //do work on a collection
}
finally
{
    if (lockTaken)
    {
        Monitor.Exit(obj);
    }
}