我有一个
Java代码重新排序和竞争条件的问题.
假设我有以下代码,同时执行2个或更多的线程workForThread()：
public class Job {
private Lock lock = new ReentrantLock();
private int sharedObject = 1;
public void workForThread() {
lock.lock();
try {
sharedObject++;
} finally {
lock.unlock();
}
}
}
JVM是否可能以错误的顺序执行？例如,以下是否可以重新排序？
sharedObject++; lock.lock(); lock.unlock();
还是保证锁不会重新排序？
解决方法
我们来看看Java文档关于Lock界面的内容：
All Lock implementations must enforce the same memory synchronization
semantics as provided by the built-in monitor lock,as described in
section 17.4 of The Java™ Language Specification:A successful lock operation has the same memory synchronization
effects as a successful Lock action.A successful unlock operation has
the same memory synchronization effects as a successful Unlock action.
所以你的问题的答案是肯定的.锁定给你同样的重新排序保证,一个常规的同步块/方法会.
