limiter_node is not decremented correctly.

[pranasge]

Simple test that hangs before reaching count:

{
	const int count = 50000;

	tbb::flow::graph graph{};
	std::atomic<int> processed;
	tbb::flow::input_node<int> input{ graph, [&](tbb::flow_control & fc) -> int {
		static int i = {}; 
		if (i++ > count) fc.stop();
		return i;
	} };
	tbb::flow::limiter_node<int, int> blockingNode{ graph, 1 };
	tbb::flow::multifunction_node<int, std::tuple<int>> processing{ graph, tbb::flow::serial, [&](const auto & value, typename decltype(processing)::output_ports_type & out) {
			if (value != count)
				std::get<0>(out).try_put(1);
			processed.store(value);
		} };

	tbb::flow::make_edge(input, blockingNode);
	tbb::flow::make_edge(blockingNode, processing);
	tbb::flow::make_edge(processing, blockingNode.decrementer());

	input.activate();

	while (true)
	{
		graph.wait_for_all();
		if (processed.load() == count)
			break;
	}
}

This test was run with: 2020_U3 and v2021.3.0 tbb versions.

[Iliamish]

Thank you for the code, we were able to reproduce the described behavior on our side! Indeed, the implementation of the limiter_node is incorrect in this regard. We will work on the issue resolution.