标签：content 执行 ola ati top over rect ons 可重入锁
1、可重入锁：
也称为递归锁，当外层函数获得该锁之后，内层递归函数仍有获取该锁的代码，结果不受影响；
java中的synchronized ReentrantLock都是可重的
举例：
public class Test implements Runnable{ public synchronized void get(){ System.out.println(Thread.currentThread().getId()); set(); } public synchronized void set(){ System.out.println(Thread.currentThread().getId()); } @Override public void run() { get(); } public static void main(String[] args) { Test ss=new Test(); new Thread(ss).start(); new Thread(ss).start(); new Thread(ss).start(); } } public class Test implements Runnable { ReentrantLock lock = new ReentrantLock(); public void get() { lock.lock(); System.out.println(Thread.currentThread().getId()); set(); lock.unlock(); } public void set() { lock.lock(); System.out.println(Thread.currentThread().getId()); lock.unlock(); } @Override public void run() { get(); } public static void main(String[] args) { Test ss = new Test(); new Thread(ss).start(); new Thread(ss).start(); new Thread(ss).start(); } }
2、自旋锁
一个线程直接循环执行一个任务，不触发临界条件，另一个线程控制临界条件，另一个线程执行时可以使前一个线程停止执行。
例子：
public class SpinLock {
private AtomicReference<Thread> sign =new AtomicReference<>();
public void lock(){
Thread current = Thread.currentThread();
while(!sign .compareAndSet(null, current)){
}
}
public void unlock (){
Thread current = Thread.currentThread();
sign .compareAndSet(current, null);
}
}
public class Test implements Runnable{ |
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public synchronized void get(){ |
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System.out.println(Thread.currentThread().getId()); |
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set(); |
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} |
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public synchronized void set(){ |
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System.out.println(Thread.currentThread().getId()); |
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} |
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@Override |
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public void run() { |
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get(); |
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} |
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public static void main(String[] args) { |
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Test ss=new Test(); |
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new Thread(ss).start(); |
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new Thread(ss).start(); |
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new Thread(ss).start(); |
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} |
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} |
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public class Test implements Runnable { |
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ReentrantLock lock = new ReentrantLock(); |
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public void get() { |
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lock.lock(); |
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System.out.println(Thread.currentThread().getId()); |
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set(); |
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lock.unlock(); |
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} |
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public void set() { |
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lock.lock(); |
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System.out.println(Thread.currentThread().getId()); |
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lock.unlock(); |
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} |
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@Override |
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public void run() { |
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get(); |
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} |
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public static void main(String[] args) { |
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Test ss = new Test(); |
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new Thread(ss).start(); |
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new Thread(ss).start(); |
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new Thread(ss).start(); |
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} |
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} |
标签：content 执行 ola ati top over rect ons 可重入锁
原文地址：https://www.cnblogs.com/hy87/p/8859021.html
