Java多线程导致数据库死锁（Java 7）答案

【问题标题】：Java multi-threading cause database deadlock (Java 7)Java多线程导致数据库死锁（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？

【问题讨论】：

标签： java multithreading thread-safety threadpool

【解决方案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。

【讨论】：