死锁

• 线程饥饿死锁

public class ThreadDeadLock {
    ExecutorService exec = Executors.newSingleThreadExecutor();
    
    /**
     * 该任务会提交另外一个任务到线程池，并且等待任务的执行结果
     * @author bh
     */
    public class RenderPageTask implements Callable<String>{
        @Override
        public String call() throws Exception {
            System.out.println("RenderPageTask 依赖LoadFileTask任务返回的结果...");
            Future<String> header,footer;
            header = exec.submit(new LoadFileTask("header.html"));
            footer = exec.submit(new LoadFileTask("footer.html"));
            String page = renderBody();
            return header.get()+page+footer.get();
        }
        
        public String renderBody(){
            return "render body is ok.";
        }
    }
    
    public static void main(String[] args) {
        ThreadDeadLock lock = new ThreadDeadLock();
        Future<String> result = lock.exec.submit(lock.new RenderPageTask());
        try {
            System.out.println("last result:"+result.get());
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }finally{
            lock.exec.shutdown();
        }
    }
}



 
class LoadFileTask implements Callable<String> {
    private String fileName;
    public LoadFileTask(String fileName){
        this.fileName = fileName;
    }
    
    @Override
    public String call() throws Exception {
        System.out.println("LoadFileTask execute call...");
        return fileName;
    }
}

• 锁顺序死锁

  
  
  

• 动态锁顺序死锁

  
  
  
  

  通过锁顺序来避免死锁

  
  
  

避免死锁