Java 9中Thread.onSpinWait()方法的重要性？
Java9中引入了Thread.onSpinWait()方法。它是Thread类的静态方法，可以选择在繁忙的等待循环中调用。它允许JVM在某些系统体系结构上发布处理器指令，以改善此类自旋等待循环中的响应时间，并减少核心线程的功耗。它可以提高Java程序的总体功耗，并允许其他核心线程在相同的功耗范围内以更快的速度执行。
语法
public static void onSpinWait()
示例
public class ThreadOnSpinWaitTest {
public static void main(final String args[]) throws InterruptedException {
final NormalTask task1 = new NormalTask();
final SpinWaitTask task2 = new SpinWaitTask();
final Thread thread1 = new Thread(task1);
thread1.start();
final Thread thread2 = new Thread(task2);
thread2.start();
new Thread(() -> {
try {
Thread.sleep(1000);
} catch(final InterruptedException e) {
e.printStackTrace();
} finally {
task1.start();
task2.sta*rt();
}
}).start();
thread1.join();
thread2.join();
}
private abstract static class Task implements Runnable {
volatile boolean canStart;
void start() {
this.canStart = true;
}
}
private static class NormalTask extends Task {
@Override public void run() {
while(!this.canStart) {
}
System.out.println("Done!");
}
}
private static class SpinWaitTask extends Task {
@Override public void run() {
while(!this.canStart) {
Thread.onSpinWait();
}
System.out.println("Done!");
}
}
}输出结果
Done! Done!