Sychronized 与Lock 对比
package XLock;
import java.util.concurrent.locks.ReentrantLock;
public class Lock {
public static void main(String[] args) {
Lock1 lock1 = new Lock1();
new Thread(lock1).start();
new Thread(lock1).start();
new Thread(lock1).start();
}
}
class Lock1 implements Runnable{
//票
int ticket=10;
private final ReentrantLock lock=new ReentrantLock();
//买票
@Override
public void run() {
while (true) {
try {
lock.lock();
if (ticket <= 0) {
return;
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(ticket--);
}
finally {
lock.unlock();
}
}
}
}
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Lock是显示锁(手动开启和关闭锁,别忘记关闭锁)
Synchronized是隐式锁,出了作用域自动释放
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Lock只用代码块锁,Synchronized有代码块锁和方法锁
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使用Lock锁,JVM将花费较少的事件来调整进程,性能更好,并且具有更好的扩展性(提供更多的子类)
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优先使用顺序
Lock 》同步代码块(已经进入了方法体,分配了相应资源)》同步方法(在方法体之外)