Stream parallel() / sequential() question. (original) (raw)

Peter Levart peter.levart at gmail.com
Thu Apr 4 13:20:30 PDT 2013

On 04/04/2013 04:05 PM, Brian Goetz wrote:

This was simplified recently.

There is one sequential/parallel bit for the whole pipeline. The stream starts off with it set one way or the other. These calls overwrite it. The bit is only acted on when you actually start the computation (invoke the terminal operation.)

Hi Brian,

So why are sequential()/parallel() methods needed then after all? We have the Collection.stream() and Collection.parallelStream() where the shape is pre-determined at the begining by the user. Is there an API that constructs a Stream where the shape is chosen automatically?

Regards, Peter

On 4/4/2013 9:21 AM, Boaz Nahum wrote:

When I invoked parallel() or sequential() how backward it goes ?

Let me explain, I wrote a simple Consumer that report how many different threads used to run it: source. parallel().peek(new ThreadReporter("Segement 1 parallel")). sequential().peek(new ThreadReporter("Segement 2 sequential")). parallel().peek(new ThreadReporter("Segement 3 parallel")). sequential().peek(new ThreadReporter("Segement 4 sequential")).forEach((t) -> {});

private static class ThreadReporter implements Consumer { @Override public void accept(Integer integer) { threads.put(Thread.currentThread(), true); } public void report() { System.out.println("Name +'" + name + "': " + threads.size() + " Thread(s)"); } }

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