java编程艺术源代码

package chapter02; import org.omg.CORBA.PRIVATE_MEMBER; import java.util.ArrayList; import java.util.List; import java.util.concurrent.atomic.AtomicInteger; /** * @author etouch * @create 2018-08-01 12:13 * @desc 基于CAS的线程安全的计数器和非线程安全的计数器 **/ public class Counter { private AtomicInteger atomicI = new AtomicInteger(0); private int i = 0; public static void main(String[] args) { final Counter cas = new Counter(); List<Thread> ts = new ArrayList<Thread>(600); long start = System.currentTimeMillis(); for (int j = 0 ; j < 100 ; j++){ Thread t = new Thread(new Runnable() { @Override public void run() { for(int i = 0 ; i < 10000; i ++){ cas.count(); cas.safeCount(); } } }); ts.add(t); } for (Thread t:ts){ t.start(); } for (Thread t:ts){ try { t.join(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println(cas.i); System.out.println(cas.atomicI.get()); System.out.println(System.currentTimeMillis()-start); } /** * 使用CAS实现线程安全计数器 */ private void safeCount() { for (;;) { int i = atomicI.get(); boolean suc = atomicI.compareAndSet(i, ++i); if (suc) { break; } } } /** * 非线程安全计数器 */ private void count() { i++; } }