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ff18504d73
One limitation of the current thread index mechanism is that if the values are assigned multiple times to the same thread and the index loops, it can match again the old value, which will not prevent a competing thread from finishing its CAS and assigning traffic to a thread that's not the optimal one. The probability is low but the solution is simple enough and consists in implementing an update counter in the high bits of the index to force a mismatch in this case (assuming we don't try to cover for extremely unlikely cases where the update counter loops while the index remains equal). So let's do that. In order to improve the situation a little bit, we now set the index to a ulong so that in 32 bits we have 8 bits of counter and in 64 bits we have 40 bits.