@Slf4j public class SingletonPerformanceTest { static long timeout = 20; // 超时时间，单位为秒 static int testIterations = 10_000_000; // 测试次数 static int threadCount = 1000; // 并发线程数 static Map<String, HashMap<String, Long>> result = new HashMap<>();
PC Register（程序计数器） 程序计数器是程序控制流的指示器，循环，跳转，异常处理，线程的恢复等工作都需要依赖程序计数器去完成。程序计数器是线程私有的，它的生命周期是和线程保持一致的，我们知道，N 个核数的 CPU 在同一时刻，最多有 N个线程同时运行，在我们真实的使用过程中可能会创建很多线程，JVM 的多线程其实是通过线程轮流切换，分配处理器执行时间来实现的。既然涉及的线程切换，所以每条线程必须有一个独立的程序计数器。
public class Test01_01 extends Thread{ @Override public void run() { for (int i = 0; i < 5; i++) { logger.info("thread sout:"+i); } } }
运行方式如下
language-java
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Thread t = new Test01_01(); t.start();
其二
实现Runnable接口，重写run方法，这种方式避免了无法继承别的类的缺陷。
language-java
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public class Test02_01 implements Runnable{ @Override public void run() { Thread cut = Thread.currentThread(); for (int i = 0; i < 5; i++) { System.out.println("thread ["+cut.getName()+"]"+i); } } }
运行方式如下
language-java
1 2
Runnable target = new Test02_01(); new Thread(target).start();
或者使用lambda表达式
language-java
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new Thread(()->{ Thread cut = Thread.currentThread(); for (int i = 0; i < 5; i++) { System.out.println("thread ["+cut.getName()+"]"+i); } }).start();
其三
实现Callable接口，重写call方法，这种方式可以取得线程的返回值。
language-java
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private static class Test04_01 implements Callable<Long>{ @Override public Long call() throws Exception { Thread cut = Thread.currentThread(); System.out.println("当前线程:"+cut.getName()); long res = 0; for (int i = 0; i < 100; i++) { for (int j = 0; j < 100; j++) { res += j; } } return res; } };
运行方式如下
language-java
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Callable<Long> call = new Test04_01(); FutureTask<Long> task = new FutureTask<>(call); new Thread(task).start(); Long l = task.get(); System.out.println(l);
ThreadPoolExecutor threadPool = new ThreadPoolExecutor(3, 5, 8, TimeUnit.SECONDS, new ArrayBlockingQueue<>(4), Executors.defaultThreadFactory(), new ThreadPoolExecutor.CallerRunsPolicy());
public class PostLock01 { private static class MyRunnable01 implements Runnable{ private int number; @Override public void run() { for (int i = 0; i < 1000; i++) { synchronized (this){ ++number; } } } }; private static class MyRunnable02 implements Runnable{ // private int number; private AtomicInteger number = new AtomicInteger(); @Override public void run() { for (int i = 0; i < 1000; i++) { number.incrementAndGet(); } } };
public class Server { public static void main(String[] args) throws Exception { //1. create server socket DatagramSocket socket = new DatagramSocket(8889); //2. create packet byte[] bytes = new byte[1024 * 64]; DatagramPacket packet = new DatagramPacket(bytes, bytes.length); while (true) { //3.receive socket.receive(packet);
public class Client { public static void main(String[] args) throws Exception { //1.create socket and send link request to server Socket socket = new Socket(InetAddress.getLocalHost().getHostAddress(), 8889); //2.get socket output for write message to server OutputStream os = socket.getOutputStream(); //3.package low os to high os DataOutputStream dos = new DataOutputStream(os);
Scanner sc = new Scanner(System.in); while (true) { System.out.println("请说"); String s = sc.nextLine(); if (s.equals("exit")){ break; } //4.write message dos.writeUTF(s); dos.flush();//立刻发送 System.out.println("已发送~"); }
import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class Test{ public static void main(String[] args) { Logger logger = LoggerFactory.getLogger(""); logger.info("This a info message"); logger.warn("This a warning message"); } }
IPV4共32bit，4字节，形如192.168.000.001
前两个为构造器，后三个为方法
