import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
@Slf4j
public class CountDownLatchExample1 {
private final static int threadCount=200;
public static void main(String[] args) throws Exception{
ExecutorService executorService= Executors.newCachedThreadPool();
final CountDownLatch countDownLatch=new CountDownLatch(threadCount);
for(int i=0;i<threadCount;i++){
final int threadNum=i;
executorService.execute(()->{
try{
test(threadNum);
}catch (Exception e){
log.error("exception",e);
}finally {
countDownLatch.countDown();
}
});
}
//countDownLatch.await(); //保证前面的线程都执行完
countDownLatch.await(10, TimeUnit.MILLISECONDS); //在规定时间内执行
log.info("finish");
}
private static void test(int threadNum) throws Exception{
Thread.sleep(100);
log.info("{}",threadNum);
Thread.sleep(100);
}
}
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
@Slf4j
public class SemaphoreExample1 {
private final static int threadCount=20;
public static void main(String[] args) throws Exception{
ExecutorService executorService= Executors.newCachedThreadPool();
final Semaphore semaphore=new Semaphore(3);
for(int i=0;i<threadCount;i++){
final int threadNum=i;
executorService.execute(()->{
try{
if(semaphore.tryAcquire()){ //可以指定执行的时间
test(threadNum);
semaphore.release();
}
//semaphore.acquire(3);//获取多个许可
//semaphore.acquire();//获取一个许可
// test(threadNum);
// semaphore.release();//释放一个许可
//semaphore.release(3);//释放多个许可
}catch (Exception e){
log.error("exception",e);
}
});
}
log.info("finish");
}
private static void test(int threadNum) throws Exception{
log.info("{}",threadNum);
Thread.sleep(100);
}
}
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.*;
@Slf4j
public class CyclicBarrierExamle1 {
//private static CyclicBarrier barrier=new CyclicBarrier(5);
private static CyclicBarrier barrier=new CyclicBarrier(5,()->{
log.info("callback is running");
});
public static void main(String[] args) throws Exception{
ExecutorService executor= Executors.newCachedThreadPool();
for(int i=0;i<10;i++){
final int threadNum=i;
Thread.sleep(1000);
executor.execute(()->{
try {
race(threadNum);
}catch (Exception e){
log.error("exception",e);
}
});
}
executor.shutdown();
}
private static void race(int threadNum) throws Exception{
Thread.sleep(100);
log.info("{} is ready",threadNum);
//barrier.await();
try {
barrier.await(2000, TimeUnit.MILLISECONDS);
}catch (BrokenBarrierException |TimeoutException e){
log.warn("BrokenBarrierException",e);
}
log.info("{}continue",threadNum);
}
}
在读取中写入的方法：ReentrantReadWriteLock
线程安全的写法。
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
@Slf4j
public class LockExample1 {
//请求总数
public static int clientTotal=5000;
//同时并发执行的线程数
public static int threadTotal=200;
public static int count=0;
private final static Lock lock=new ReentrantLock();
public static void main(String[] args) throws Exception{
ExecutorService executorService= Executors.newCachedThreadPool();
final Semaphore semaphore=new Semaphore(threadTotal);
final CountDownLatch countDownLatch=new CountDownLatch(clientTotal);
for(int i=0;i<clientTotal;i++){
final int count=i;
executorService.execute(()->{
try {
semaphore.acquire();
add(count);
semaphore.release();
}catch (Exception e){
log.error("exception",e);
}
countDownLatch.countDown();
});
}
countDownLatch.await();
executorService.shutdown();
log.info("size{}",count);
}
private static void add(int i){
lock.lock();
try {
count++;
}finally {
lock.unlock();
}
}
}
import lombok.extern.slf4j.Slf4j;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
@Slf4j
public class LockExample2 {
private final Map<String, Data> map=new TreeMap<>();
private final ReentrantReadWriteLock lock=new ReentrantReadWriteLock();
private final Lock readLock=lock.readLock();
private final Lock writeLock=lock.writeLock();
public Data get(String key){
readLock.lock();
try {
return map.get(key);
}finally {
readLock.unlock();
}
}
public Set<String> getAllKeys(){
readLock.lock();
try {
return map.keySet();
}finally {
readLock.unlock();
}
}
public Data put(String key, Data value){
writeLock.lock();
try {
return map.put(key, value);
}finally {
readLock.unlock();
}
}
class Data{
}
}
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import java.util.concurrent.locks.StampedLock;
@Slf4j
public class LockExample5 {
//请求总数
public static int clientTotal=5000;
//同时并发执行的线程数
public static int threadTotal=200;
public static int count=0;
private final static StampedLock lock=new StampedLock();
public static void main(String[] args) throws Exception{
ExecutorService executorService= Executors.newCachedThreadPool();
final Semaphore semaphore=new Semaphore(threadTotal);
final CountDownLatch countDownLatch=new CountDownLatch(clientTotal);
for(int i=0;i<clientTotal;i++){
final int count=i;
executorService.execute(()->{
try {
semaphore.acquire();
add(count);
semaphore.release();
}catch (Exception e){
log.error("exception",e);
}
countDownLatch.countDown();
});
}
countDownLatch.await();
executorService.shutdown();
log.info("size{}",count);
}
private static void add(int i){
long stamp= lock.writeLock();
try {
count++;
}finally {
lock.unlock(stamp);
}
}
}
import java.util.concurrent.locks.StampedLock;
public class LockExample4 {
class Point{
private double x,y;
private final StampedLock sl=new StampedLock();
void move(double deltaX,double deltaY){
long stamp=sl.writeLock();
try{
x+=deltaX;
y+=deltaY;
}finally {
sl.unlockWrite(stamp);
}
}
//乐观锁案例
double distanceFromOrigin(){
long stamp=sl.tryOptimisticRead();//获得一个乐观读锁
double currentX=x,currentY=y;//将两个字段读入本地局部变量
if(!sl.validate(stamp)){ //检查发出乐观锁后同时是否有其他锁发生
stamp=sl.readLock();//没有，再次获取一个读悲观锁
try{
currentX=x; //将两个字段读入本地局部变量
currentY=y; //将两个字段读入本地局部变量
}finally {
sl.unlockRead(stamp);
}
}
return Math.sqrt(currentX*currentX+currentY*currentY);
}
//悲观锁读写案例
void moveIfAtOrigin(double newX,double newY){
long stamp=sl.readLock();
try {
while (x==0.0&&y==0.0){ //循环，检查当前状态是否符合
long ws=sl.tryConvertToWriteLock(stamp);//将读锁转化为写锁
if(ws!=0L){ //确认转为写锁是否成功
stamp=ws; //如果成功，替换票据
x=newX; //进行状态改变
y=newY; //进行状态改变
break;
}else {
sl.unlockRead(stamp);//如果不能成功转化为写锁
stamp=sl.writeLock();//显示直接进行写锁，然后通过循环再试
}
}
}finally {
sl.unlock(stamp);//释放读锁和写锁
}
}
}
}
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
@Slf4j
public class LockExample6 {
public static void main(String[] args) {
ReentrantLock reentrantLock=new ReentrantLock();
Condition condition=reentrantLock.newCondition();
new Thread(()->{
try {
reentrantLock.lock();
log.info("wait signal");
condition.await();
}catch (InterruptedException e){
e.printStackTrace();
}
log.info("get signal");
reentrantLock.unlock();
}).start();
new Thread(()->{
reentrantLock.lock();
log.info("get lock");
try {
Thread.sleep(300);
}catch (InterruptedException e){
e.printStackTrace();
}
condition.signalAll();
log.info("send signal~");
reentrantLock.unlock();
}).start();
}
}