SingleProducerConstrained and MaxDegreeOfParallelism

Question

In the C# TPL Dataflow library, SingleProducerConstrained is an optimisation option for ActionBlocks you can use when only a single thread is feeding the action block:

Answer 1

Yes, I think it's considered a single producer.

This is because all the built-int blocks maintain ordering, so item 2 can be offered (using the OfferMessage() method) to the target block only after item 1 has been accepted. And this constraint means that there can be only one thread offering messages to the target at a time, which follows the definition of "single producer".