Question

Is there a neat way to do this using the Interlocked class? Or should I just use lock { }?

My specific use case is that I have multiple threads that compute a long value, and compare it to a shared “Maximum” value, replacing the shared value only if the local value is larger.

Answer 1

Try the Interlocked.CompareExchange method. I haven’t tried, but something like this seems logical to me:

long localMax = Interlocked.Read(ref max);
while (value > localMax) {
  Interlocked.CompareExchange(ref max, value, localMax);
  localMax = Interlocked.Read(ref max);
}

As usual, stress test your code to try to catch concurrency issues.