说明
在使用LinkedBlockingQueue的offer方法时,出现了中断异常,现分析一下出现这个中断异常的原因。
会产生中断异常的Demo
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
public class TestLinkedBlockingQueue {
public static void main(String[] args) {
LinkedBlockingQueue lbq = new LinkedBlockingQueue(3);
for(int i = 0; i < 10; i++){
try {
System.out.println(lbq);
//这里用offer方法往阻塞队列里面添加对象,此方法表示若队列满了,则等待1秒,1秒后若队列还是满的,则丢弃数据。
lbq.offer(i, 1000, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Thread.currentThread().interrupt();//如果注释掉这行代码,则此程序不会抛出异常
}
}
}
LinkedBlockingQueue的offer源码方法
public boolean offer(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) throw new NullPointerException();
long nanos = unit.toNanos(timeout);
int c = -1;
final ReentrantLock putLock = this.putLock;
final AtomicInteger count = this.count;
putLock.lockInterruptibly();
try {
while (count.get() == capacity) {
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
}
enqueue(new Node<E>(e));
c = count.getAndIncrement();
if (c + 1 < capacity)
notFull.signal();
} finally {
putLock.unlock();
}
if (c == 0)
signalNotEmpty();
return true;
}
//lockInterruptibly方法
public void lockInterruptibly() throws InterruptedException {
sync.acquireInterruptibly(1);
}
//acquireInterruptibly方法
public final void acquireInterruptibly(int arg)
throws InterruptedException {
if (Thread.interrupted())
throw new InterruptedException();
if (!tryAcquire(arg))
doAcquireInterruptibly(arg);
}
所以,当线程被标记有中断标志时,offer添加时将获取不到锁,直接抛出中断异常。