java多线程之测试并发（1）-监控Lock

Love The Way You Lie 2022-05-28 01:08 47阅读 0赞

一、Lock是java并发同步代码块的工具之一。我们可以通过监控Lock知道哪个线程获取到了锁，哪个线程释放了锁，那些线程正在等待锁。

二、监控Lock

package com.np.ota.test.synctest.lock;
    
    import java.util.Collection;
    import java.util.concurrent.locks.ReentrantLock;
    
    /**
     * 自定义Lock
     * @author luke
     */
    public class MyLock extends ReentrantLock{
    
    	private static final long serialVersionUID = 1L;
    	
    	public MyLock(){
    		super(true);
    	}
    	
    	public String getOwnerName(){
    		if(this.getOwner() == null){
    			return "none";
    		}
    		return this.getOwner().getName();
    	}
    
    	//Returns a collection containing threads that may be waiting to acquire this lock
    	//Because the actual set of threads may change dynamically while constructing this result
    	//获取等待该锁的所有线程集合，但结果不是绝对准确的
    	public Collection<Thread> getThreads(){
    		return this.getQueuedThreads();
    	}
    	
    }

package com.np.ota.test.synctest.lock;
    
    import java.util.concurrent.TimeUnit;
    import java.util.concurrent.locks.Lock;
    
    public class Task implements Runnable{
    	
    	private Lock lock;
    	
    	public Task(Lock lock) {
    		this.lock = lock;
    	}
    
    	@Override
    	public void run() {
    		for(int i = 0; i < 5; i++){
    			lock.lock();
    			System.out.println(Thread.currentThread().getName()+" get the lock");//获得锁的线程
    			try {
    				TimeUnit.MILLISECONDS.sleep(500);
    			} catch (InterruptedException e) {
    				e.printStackTrace();
    			}finally{
    				System.out.println(Thread.currentThread().getName()+" free the lock");//线程释放锁
    				lock.unlock();
    			}
    		}
    	}
    
    }

package com.np.ota.test.synctest.lock;
    
    import java.util.Collection;
    import java.util.concurrent.TimeUnit;
    
    /**
     * 监控Lock
     * @author luke
     */
    public class Main {
    
    	public static void main(String[] args){
    
    		//创建自定义锁，方便监控
    		MyLock lock = new MyLock();
    		
    		//创建5个线程，并执行
    		Thread[] threads = new Thread[5];
    		for(int i = 0; i < 5; i++){
    			Task task = new Task(lock);
    			threads[i] = new Thread(task);
    			threads[i].start();
    		}
    		
    		//监控Lock
    		for(int i = 0; i < 15; i++){
    			System.out.println("***************************");
    			System.out.println("Lock Owner : "+lock.getOwnerName());//锁的拥有者
    			System.out.println("Lock queued Threads: "+lock.hasQueuedThreads());//是否有线程正在等待获取该锁
    			if(lock.hasQueuedThreads()){
    				System.out.println("waitting Lock queue length: "+lock.getQueueLength());//该瞬间等待该锁的线程数
    				Collection<Thread> lockthreads = lock.getThreads();//遍历该瞬间等待该锁的线程
    				for(Thread lockthread : lockthreads){
    					System.out.println("waitting lock thread:"+lockthread.getName());
    				}
    			}
    			System.out.println("lock fairness:"+lock.isFair());
    			System.out.println("lock locked:"+lock.isLocked());
    			System.out.println("***************************");
    			try {
    				TimeUnit.SECONDS.sleep(1);
    			} catch (InterruptedException e) {
    				e.printStackTrace();
    			}
    		}
    		
    	}
    
    }

结果：

Thread-0 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-0  
Lock queued Threads: true  
waitting Lock queue length: 1  
waitting lock thread:Thread-3  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-0 free the lock  
Thread-3 get the lock  
Thread-3 free the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-3  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-1 get the lock  
Thread-1 free the lock  
Thread-2 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-2 free the lock  
Lock Owner : Thread-2  
Thread-4 get the lock  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
waitting lock thread:Thread-0  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-4 free the lock  
Thread-0 get the lock  
Thread-0 free the lock  
Thread-3 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-3  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-3 free the lock  
Thread-1 get the lock  
Thread-1 free the lock  
Thread-2 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-2  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-2 free the lock  
Thread-4 get the lock  
Thread-4 free the lock  
Thread-0 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-0  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-0 free the lock  
Thread-3 get the lock  
Thread-3 free the lock  
Thread-1 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-1  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-3  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-1 free the lock  
Thread-2 get the lock  
Thread-2 free the lock  
Thread-4 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-4  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
waitting lock thread:Thread-0  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-4 free the lock  
Thread-0 get the lock  
Thread-0 free the lock  
Thread-3 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-3  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-3 free the lock  
Thread-1 get the lock  
Thread-1 free the lock  
Thread-2 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-2  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
waitting lock thread:Thread-0  
waitting lock thread:Thread-4  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-2 free the lock  
Thread-4 get the lock  
Thread-4 free the lock  
Thread-0 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-0  
Lock queued Threads: true  
waitting Lock queue length: 4  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
waitting lock thread:Thread-1  
waitting lock thread:Thread-3  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-0 free the lock  
Thread-3 get the lock  
Thread-3 free the lock  
Thread-1 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-1  
Lock queued Threads: true  
waitting Lock queue length: 2  
waitting lock thread:Thread-4  
waitting lock thread:Thread-2  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-1 free the lock  
Thread-2 get the lock  
Thread-2 free the lock  
Thread-4 get the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : Thread-4  
Lock queued Threads: false  
lock fairness:true  
lock locked:true  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Thread-4 free the lock  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : none  
Lock queued Threads: false  
lock fairness:true  
lock locked:false  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*  
Lock Owner : none  
Lock queued Threads: false  
lock fairness:true  
lock locked:false  
\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*