在单独的线程中将对象返回池

Question

There is a loop which polls for borrowing Objects from a GenericObjectPool. Pool itself is of size 1. Code below -

final CompletionService completionService = new ExecutorCompletionService(getExecutorServices());               
int counter = 0;

    for (Iterator iter = AList.iterator(); iter.hasNext();) {

                borrowed = this.getPool().borrowObject();

                if (borrowed == null) {
                    throw new Exception("not set");
                } else {        
                    completionService.submit(borrowed,borrowed);
                    counter ++;
                }   
    }   

Since pool is of size 1, after 1st borrow, it is exhausted and blocked. To return Objects back to pool, I think to run a separate Thread as below -

new Runnable() {

    public void run() {
        for (int i = 0; i < counter; i++) {

            borrowed = completionService.take().get();
            status = borrowed.getStatus();

            getPool().returnObject(borrowed);
                        counter --;

            if (status = 1) {
                getExecutorServices().shutdownNow();
                return;
            }
        }
    }

};

This is a blocking call to CompletionService for acting on completion of each Thread and releasing it for making it available for borrow.

But this design has shortcomings like counter of parent can not be read from Runnable.

Answer 1

The counter is not thread-safe. Use an AtomicInteger and make it available to both the runnable and the first code block.

Answer 2

我创建了一个CallableDecorator以返回值形式Runnable来监视Thread并对其进行了修复。