关于blockingqueue和多线程消费者的一些困惑

Question

我正在编写这样的多线程代码（由于相关性，省略了很多细节）：

public class Producer {

    private static BlockingQueue<Transaction> transactionsQueue = new LinkedBlockingQueue<Transaction>();
    private static ArrayList<C> consumersList = new ArrayList<C>();

    public Producer(int a, int b) {
        for (int i = 0; i < a; i++)
            accountsList.add(new Account(i, DEFAULT_BALANCE));

        for (int i = 0; i < b; i++)
            consumersList.add(new Consumer());

        for (Consumer c : consumersList)
            c.start(); //question line of code
    }


    public class Consumer extends Thread{
        @Override
        public void run(){
            while (true) {
                try {
                    Transaction nextTransaction = transactionsQueue.take();

                    if(nextTransaction.equals(FINAL_TRANSACTION))
                        break;

                    Account acc = accountsList.get(nextTransaction.getTo());
                    acc.makeTransaction(nextTransaction);
                    System.out.println(acc);

                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public static void main(String []args){
        try{
            launch(args[0], NUM_OF_ACCOUNTS, Integer.parseInt(args[1]));
        }catch (Exception e){
            System.out.println("Incorrect args. Starting with default arguments");
            launch(SMALL_FILE, NUM_OF_ACCOUNTS, NUM_OF_THREADS);
        }
    }

    private static void launch(String filename, int numOfAccounts, int numOfConsumers) {
        Producer bank = new Producer(numOfAccounts, numOfConsumers);
        bank.createTransactionsQueue(filename); //start putting into transactionsQueue
        bank.close();
    }
}

我的问题是，当程序在 Producer 的构造函数中执行 for (Consumer c : consumersList) c.start(); 时，消费者线程的 run() 方法是否立即被调用？如果是这样，当 transactionsQueue 为空时会发生什么——因为我在 bank.createTransactionsQueue(filename); 处开始 put 进入 transactionsQueue，这是在调用构造函数（并创建消费者线程）之后.

Answer 1

消费者将阻塞（等待）transactionsQueue.take()，直到队列中有对象或直到线程被中断

Answer 2

does the consumer threads's run() method immediately gets called

它很快就会被调用。它不是下一行执行的，而是在新线程真正启动时执行的。

If so what happens when the transactionsQueue is empty

其他线程运行将被挂起，直到队列中有一个元素。对于放置的每个元素，将唤醒一个线程以将元素从队列中拉出。

关于blockingqueue和多线程消费者的一些困惑

Some confusion about blockingqueue and multithreaded consumer

java

multithreading

producer-consumer