this should be easy to test with some timeout reads, but I’d assume that what it would actually do is wait until from gives it a nil (meaning channel is closed and buffer drained) and then only close the to when all puts resulting via processing from have completed (and once again, the consumer of to wouldn’t see the close until the buffer is drained)

this is the implementation function pipeline-async invokes https://github.com/clojure/core.async/blob/master/src/main/clojure/clojure/core/async.clj#L478 but I can’t tell for sure from reading the code if the issue you describe holds

thanks ya I did a few tests and there didn't seem to be any race conditions, but that doesn't mean it can't happen. I too tried quickly reading through that code and wasn't 100% sure if it could still happen. I guess I'll have to take the time to read it more thoroughly

there are ways to make race conditions more likely - randomized delay times, running thousands of iterations and verifying if any of them raced