我有三星Galaxy S3，它使用了自家的Exynos 4四核处理​​器。 所以，我要优化我的应用程序，它可以使用处理器的所有4个内核。

I have Samsung Galaxy S3, which used its own Exynos 4 Quad processor. So I want to optimize my app, that it can use all 4 cores of processor.

所以我做了一些测试：

在一个线程中运行任务。处理时间 - 8秒

Run task in one thread. Processing time - 8 seconds.

在四线程运行的任务。处理时间 - 还是8秒

Run task in four threads. Processing time - still 8 sec.

 new Thread() {
    public void run() {
                    // do 1/4 of task
    }
}.start();

new Thread() {
    public void run() {
                    // do 1/4 of task
    }
}.start();

new Thread() {
    public void run() {
                    // do 1/4 of task
    }
}.start();

new Thread() {
    public void run() {
                    // do 1/4 of task
    }
}.start();

在ExecutorService的运行任务。和处理时间 - 还是8秒

Run task in ExecutorService. And processing time - still 8 sec.

ExecutorService threadPool = null;
threadPool = Executors.newFixedThreadPool(4);

threadPool.execute(new Runnable() {
    @Override
    public void run() {
         // do 1/4 of task
                      }});
threadPool.execute(new Runnable() {
    @Override
    public void run() {
         // do 1/4 of task
                      }});
threadPool.execute(new Runnable() {
    @Override
    public void run() {
         // do 1/4 of task
                      }});
threadPool.execute(new Runnable() {
    @Override
    public void run() {
         // do 1/4 of task
                      }});

看起来像同步完成所有的工作。为什么它不是并联？

Looks like all work done synchronously. Why its not paralleling ?

推荐答案

您可以尝试用C或Java我的测试中，

You can try my tests, in C or Java:

http://bigflake.com/cpu-spinner.c.txt < BR>    http://bigflake.com/MultiCore.java.txt

http://bigflake.com/cpu-spinner.c.txt http://bigflake.com/MultiCore.java.txt

当MultiCore.java运行在一台Nexus 4，我明白了：

When MultiCore.java is run on a Nexus 4, I see:

Thread 1 finished in 1516ms (1267234688)
Thread 3 finished in 1494ms (1519485328)
Thread 0 finished in 1530ms (51099776)
Thread 2 finished in 1543ms (-1106614992)
All threads finished in 1550ms

更新： 它是有用的观看测试与systrace。作为回答了类似的一部分question我建立了一个网页，显示systrace输出此测试。你可以看到线程调度，并观看了另外两个内核旋转起来。

Update: It's useful to watch the test with systrace. As part of answering a similar question I set up a page that shows the systrace output for this test. You can see how the threads are scheduled, and watch the other two cores spin up.