信号量被多次中断的问题

我有一个信号量,它限制用户一次下载n个文件。每个文件都在单独的线程中下载。

编辑 :修改了示例,以便正确发布

import java.util.concurrent.Semaphore;
public void downloadFile() {
    Thread downloadThread = new Thread() {
        boolean bSemaphoreAcquired = false;
        public void run() {
            try {
                semaphore.acquire();
                bSemaphoreAcquired = true;
                // do the download
            } catch (InterruptedException e) {
            } finally {
                if (bSemaphoreAcquired) semaphore.release();
            }
        }
    };
    // add download thread to the list of download threads
    downloadThread.start();
}

现在,一旦获得了信号量的所有许可,任何新的下载都将等待先前的下载完成。

当用户选择取消正在等待获取调用的下载时,我调用interrupt()方法来终止该下载线程。 我面临的问题是,一旦这个信号量被中断,它将不会第二次抛出InterruptedException异常!!创建的任何新线程都将永远等待Acquire方法!

Sequence of events (Semaphore that permits 2 threads)
- thread 1 downloading
- thread 2 downloading
- thread 3 waiting on acquire()
- thread 3 is cancelled (interrupt() is called). InterruptedException is thrown and the thread exits
- thread 4 is created and is now waiting on acquire()
- thread 4 is cancelled (interrupt() is called). InterruptedException IS NOT THROWN ANYMORE!!!

这是线程4的堆栈跟踪

Semaphore$FairSync(AbstractQueuedSynchronizer).fullGetFirstQueuedThread() line: 1276    
Semaphore$FairSync(AbstractQueuedSynchronizer).getFirstQueuedThread() line: 1232    
Semaphore$FairSync.tryAcquireShared(int) line: 201  
Semaphore$FairSync(AbstractQueuedSynchronizer).acquireSharedInterruptibly(int) line: 1142   
Semaphore.acquire() line: 267
FileDownloadManager$1.run() line: 150   

为什么线程4没有收到异常?