Java 9 中 Thread.onSpinWait() 方法的重要性?
Thread.onSpinWait() 方法已在 Java 9 中引入。它是 Thread 類的靜態方法,可以在忙等待迴圈中按需呼叫。在某些系統架構上,它允許 JVM 發出處理器指令以改善此類自旋等待迴圈的反應時間,同時降低核心執行緒的耗電量。它可以使 Java 程式的整體功耗受益,並允許其他核心執行緒在相同的功耗範圍內以更快的速度執行。
語法
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!"); } } }
輸出
Done! Done!
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