example 2_concurrent_even_number_counting don't functionally in working thread

[hongxinGuo]

Hi,
I run this example in a working thread. the function count_even returned without waiting "co_await result". How cound I changed the code to fix it?

for (auto& result : chunk_count) {
	total_count += co_await result;
}
co_return total_count;

I have found the problem. The working thread caller should't be created by thread_pool_executor or background_executor, thread_executor is OK. But why?