Implementing lock-free updates using Interlocked.CompareExchange:

public static void UpdateMax(ref int target, int newValue)
{
    int current = target;
    while (newValue > current)
    {
        int previous = Interlocked.CompareExchange(ref target, newValue, current);
        if (previous == current) break; // Successful atomic update!
        current = previous;
    }
}

Executes with a single atomic hardware CMPXCHG instruction on x86, avoiding OS kernel thread suspension and context switches!

Interlocked.CompareExchange loops (CAS loops) are the foundation of lock-free data structures in .NET.

Much faster than lock(obj) when contention is short and infrequent.