Question

我有像这样的ExecutorService

ExecutorService executor =  new ThreadPoolExecutor(threads, threads,
            0L, TimeUnit.MILLISECONDS,
            new ArrayBlockingQueue<>(1000, true));

我正在使用.execute（Runnable）

向其发送作品

我的runnable有

        @Override
        public void run() {
            this.processor.performAction(this);
        }

处理器有

public void performAction(RunnableAction action) {
        Lock lock = lockManager.getLock(action.getId());
        lock.lock();
        try {
            action.execute();
        } finally {
            lock.unlock();
        }
    }

其中lockManager是

public class LockManager {

    Map<String, Lock> lockById = new HashMap<>(1000);

    public synchronized Lock getLock(String id) {
        Lock lock = lockById.get(id);
        if (lock == null) {
            lock = new ReentrantLock(true);
        }
        return lock;
    }

并且我的actions / runnable有一个execQty字段，触发对某些命令的更新，调用它们的order.execute（execQty）

public void execute(int execQty) {
        if (execQty < this.lastExecQty) {
            System.err.println("<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
            System.err.println("id: " + this.id + " wrong order" + this.lastExecQty + " > " + execQty);
        }
        this.execQty += execQty;
        this.lastExecQty = execQty;
    }
}

我已经命令我的runnables发送到调度程序，每个qty字段都比前一个更大，所以在将每个runnable发送到ExecutorService之前打印我总是得到我需要的，有序的数字：

execute: id: 49  qty: 819
execute: id: 49  qty: 820
execute: id: 49  qty: 821
execute: id: 49  qty: 822
execute: id: 49  qty: 823

但即使我的ExecutorService由公平队列支持，并且我在每个实体更新之前使用每个实体锁，它仍然看起来实体没有按顺序更新

execute: id: 88  qty: 6
execute: id: 88  qty: 7
execute: id: 88  qty: 8
execute: id: 88  qty: 9
execute: id: 88  qty: 10
execute: id: 88  qty: 11
execute: id: 88  qty: 12
execute: id: 88  qty: 13
execute: id: 88  qty: 14
execute: id: 88  qty: 15
execute: id: 88  qty: 16
execute: id: 88  qty: 17
execute: id: 88  qty: 18
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
id: 88 wrong order 17 (previous) > 7 (current)
execute: id: 88  qty: 19
execute: id: 88  qty: 20

仅使用一个线程

运行ExecutorService时，它可以正常工作

Answer 1

你的LockManager看起来不对。您永远不会将这些锁放入地图中，因此您始终在同步新对象。

建议更改：

public synchronized Lock getLock(String id) {
    Lock lock = lockById.get(id);
    if (lock == null) {
        lock = new ReentrantLock(true);
        // put lock into the map so that next one will reuse it
        lockById.put(id, lock);
    }
    return lock;
}

ExecutorService公平

1 个答案: