Java程序员修炼之道（一）-并发中产生的死锁

Java程序员修炼之道的代码 https://download.csdn.net/download/penker_zhao/13452596
重温埃文斯的Java程序员修炼之道，在第三章中运行示例，发现运行了几次不能死锁，所以改了下代码，让其产生死锁，具体死锁原因，请自行浏览书本获取：

package com.java7developer.chapter4;

public class DeadlockMicroBlogNode implements SimpleMicroBlogNode {

  private static Update getUpdate(String s) {
    Update.Builder b = new Update.Builder();
    b.updateText(s).author(new Author("Ben"));

    return b.build();
  }

  private final String ident;

  public DeadlockMicroBlogNode(String ident_) {
    ident = ident_;
  }

  public String getIdent() {
    return ident;
  }

  @Override
  public synchronized void propagateUpdate(Update upd_,
      SimpleMicroBlogNode backup_) {
    System.out.println(ident + ": recvd: " + upd_.getUpdateText()
        + " ; backup: " + backup_.getIdent());
    try {
      Thread.sleep(3000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    backup_.confirmUpdate(this, upd_);
  }

  @Override
  public synchronized void confirmUpdate(SimpleMicroBlogNode other_,
      Update update_) {
    System.out.println(ident + ": recvd confirm: " + update_.getUpdateText()
        + " from " + other_.getIdent());
  }

  public static void main(String[] a) {
    final DeadlockMicroBlogNode local = new DeadlockMicroBlogNode(
        "localhost:8888");
    final DeadlockMicroBlogNode other = new DeadlockMicroBlogNode(
        "localhost:8988");
    final Update first = getUpdate("1");
    final Update second = getUpdate("2");

    new Thread(new Runnable() {
      public void run() {
        local.propagateUpdate(first, other);
      }
    }).start();

    new Thread(new Runnable() {
      public void run() {
        other.propagateUpdate(second, local);
      }
    }).start();
  }

}

修改UpdateSorterMain.java文件，让其可以成功运行，

public static void main(String[] args) {
  
  

这段代码有几点巧妙，5行代码就有四个知识点，可以仔细品读下：

Collections.shuffle(lu);
Update[] updates = lu.toArray(new Update[0]); // Avoid allocation by passing
                                              // zero-sized array
MicroBlogUpdateSorter sorter = new MicroBlogUpdateSorter(updates);
ForkJoinPool pool = new ForkJoinPool(4);
pool.invoke(sorter);