import org.junit.jupiter.api.Test;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* @Author: ZhangHao
* @Description: ReentrantLock测试相关
* @Date: 2020/10/15 21:21
* @Version: 1.0
*/
public class ReentrantLockTest {
/**
* 线程可见性:数据修改立刻被其他线程可见
* 数据操作原子性:不可分割的数据操作
*/
/**
* 没有线程可见性,数据操作原子性
*/
private int i1 = 0;
@Test
void test1(){
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
i1++;
}).start();
}
while (Thread.activeCount() > 2) Thread.yield();
System.out.println(i1);
}
/**
* 有线程可见性,没有数据操作原子性
*/
private volatile int i2 = 0;
@Test
void test2(){
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
i2++;
}).start();
}
while (Thread.activeCount() > 2) Thread.yield();
System.out.println(i2);
}
/**
* Finalizer和main线程存活
*/
private static volatile int i3 = 0;
public static void main(String[] args) {
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
i3++;
}).start();
}
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
e.printStackTrace();
}
Thread.getAllStackTraces().entrySet();
System.out.println(Thread.activeCount());
/*while (Thread.activeCount() > 2) Thread.yield();*/
while (Thread.activeCount() > 2) Thread.onSpinWait();
System.out.println(i3);
}
/**
* AtomicInteger的getAndIncrement()底层是Unsafe的CAS:compareAndSetInt(Object o, long offset, int expected, int x)
* 有线程可见性,有数据操作原子性
*/
private AtomicInteger i4 = new AtomicInteger();
@Test
void test4(){
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
i4.getAndIncrement();
}).start();
}
while (Thread.activeCount() > 2) Thread.yield();
System.out.println(i4);
}
/**
* 同步锁
* 有线程可见性,有数据操作原子性
*/
private int i5 = 0;
@Test
void test5(){
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
/*synchronized (ReentrantLockTest.class){
i4++;
}*/
synchronized (this){
i5++;
}
}).start();
}
while (Thread.activeCount() > 2) Thread.yield();
System.out.println(i5);
}
/**
* 可重入锁
* 有线程可见性,有数据操作原子性
*/
private int i6 = 0;
private Lock lock = new ReentrantLock();
@Test
void test6(){
for(int j = 0;j < 1000;j++){
new Thread(() -> {
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
lock.lock();
i6++;
lock.unlock();
}).start();
}
while (Thread.activeCount() > 2) Thread.yield();
System.out.println(i6);
}
}
线程可见性、数据操作原子性、volatile、原子量、同步锁、可重入锁示例
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转载自blog.csdn.net/haoranhaoshi/article/details/109112211
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