Java多线程导致数据库死锁（Java 7）

Posted 2023-03-15

【中文标题】Java多线程导致数据库死锁（Java 7）

【英文标题】：Java multi-threading cause database deadlock (Java 7)

【发布时间】：2018-11-09 23:02:34

【问题描述】：

我想设计一个多线程模块，我设置了两个类，设计如下：

ThreadConcurrentWoker.class：

public class ThreadConcurrentWoker<E, R> extends ThreadConcurrent<E, R> 

public ThreadConcurrentWoker(List<E> traget, CallableModel<E, R> callable) 
    super.targetList = traget; // a list want to doing in thread.
    super.callable = callable; // Custom callable object
    super.results = new Vector<R>(); // get result in to this list


// this is doing Thread method
@Override
public List<R> concurrentExcute() throws Exception 

    ExecutorService executor = Executors.newFixedThreadPool(super.targetList.size());
    CompletionService<R> completionService = new ExecutorCompletionService<R>(executor);
    for (final E elememt : super.targetList) 
        completionService.submit(new Callable<R>() 
            @Override
            public R call() throws Exception 
                callable.setElement(elememt);
                return callable.call();
            
        );
    

    int finishs = 0;
    boolean errors = false;

    while (finishs < super.targetList.size() && !errors) 
        Future<R> resultFuture = completionService.take();
        try 
            super.results.add(resultFuture.get());
         catch (ExecutionException e) 
            errors = true;
         finally 
            finishs++;
        
    
    return super.results;

CallableModel.class：

public abstract class CallableModel<E, V> implements Callable<V> 
    private E element;

    public E getElement() 
        return element;
    

    public void setElement(E element) 
        this.element = element;
    

我想这样使用：

ThreadConcurrentWoker<FlowPendingCheckedBean, ResultBean> tCUtil = 
new ThreadConcurrentWoker<>(test, new CallableModel<FlowPendingCheckedBean, ResultBean>() 

    @Override
    public ResultBean call() throws Exception 
        // do something in here and return result.
    

);
try 
    resultBeans = tCUtil.concurrentExcute();
 catch (Exception e1) 
    log.error(e1.getMessage());

但是当我执行这个类时，它会在不同的线程中得到相同的数据。 导致数据库会出现死锁。 我该如何改进它？

【参考方案1】：

我试过这个问题。写下笔记：

由于多线程使用相同的CallableModel元素，所以当第一个线程调用方法时，第二个线程进入setEelement改变元素，这一次，第一个线程将获得第二个线程的元素。