近日于LeetCode看题遇1114年按序打印,获悉一解法使用了信号量,顺势研究,记心得于此。
此解视信号为锁,以保证同一时刻单线程的顺序执行。在此原题上,我作出如下更改。
包装测试;
进口java.util.concurrent.ExecutorService;
进口java.util.concurrent.Executors;
进口java.util.concurrent.Semaphore;
公开课SemaphoreDemo {
静态信号;
静态信号B;
静态信号C;
公共静态void main (String [] args)抛出InterruptedException {=new信号(1);
B=新的信号量(0);
C=新的信号量(0);
ExecutorService=Executors.newFixedThreadPool交货(10);
for (int i=0;我& lt; 7;我+ +){
ex.execute(新R1 ());
ex.execute(新R2 ());
ex.execute(新R3 ());
}
ex.shutdown ();
}
公共静态类R1实现Runnable {
@Override
公共空间run () {
尝试{//A.acquire ();
System.out.println (“1”+ Thread.currentThread () . getname ());//B.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
公共静态类R2实现Runnable {
@Override
公共空间run () {
尝试{//B.acquire ();
System.out.println (“2”+ Thread.currentThread () . getname ());//C.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
公共静态类R3实现Runnable {
@Override
公共空间run () {
尝试{//C.acquire ();
System.out.println (“3”+ Thread.currentThread () . getname ());//A.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
}
之前
10个线程的常量池中,分别调用R1, R2, R3的方法多次,控制台输出对应各方法名拼接执行该方法的线程名。多次执行结果各不相同:
1 pool-1-thread-1
2 pool-1-thread-2
1 pool-1-thread-4
3 pool-1-thread-6
2 pool-1-thread-5
3 pool-1-thread-3
1 pool-1-thread-7
2 pool-1-thread-8
3 pool-1-thread-9
3 pool-1-thread-1
2 pool-1-thread-8
1 pool-1-thread-4
3 pool-1-thread-1
1 pool-1-thread-2
2 pool-1-thread-9
1 pool-1-thread-10
3 pool-1-thread-1
2 pool-1-thread-5
1 pool-1-thread-6
3 pool-1-thread-4
2 pool-1-thread-8
之前
1 pool-1-thread-1
2 pool-1-thread-2
3 pool-1-thread-3
1 pool-1-thread-4
2 pool-1-thread-5
3 pool-1-thread-6
1 pool-1-thread-7
2 pool-1-thread-8
3 pool-1-thread-9
1 pool-1-thread-10
3 pool-1-thread-1
1 pool-1-thread-4
2 pool-1-thread-8
3 pool-1-thread-3
2 pool-1-thread-10
1 pool-1-thread-2
2 pool-1-thread-9
3 pool-1-thread-4
1 pool-1-thread-7
3 pool-1-thread-6
2 pool-1-thread-5
之前
方法能调用,多线程下却无法保证方法的顺序执行。使用信号量后,代码为:
包装测试;
进口java.util.concurrent.ExecutorService;
进口java.util.concurrent.Executors;
进口java.util.concurrent.Semaphore;
公开课SemaphoreDemo {
静态信号;
静态信号B;
静态信号C;
公共静态void main (String [] args)抛出InterruptedException {=new信号(1);
B=新的信号量(0);
C=新的信号量(0);
ExecutorService=Executors.newFixedThreadPool交货(10);
for (int i=0;我& lt; 7;我+ +){
ex.execute(新R1 ());
ex.execute(新R2 ());
ex.execute(新R3 ());
}
ex.shutdown ();
}
公共静态类R1实现Runnable {
@Override
公共空间run () {
尝试{
A.acquire ();
System.out.println (“1”+ Thread.currentThread () . getname ());
B.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
公共静态类R2实现Runnable {
@Override
公共空间run () {
尝试{
B.acquire ();
System.out.println (“2”+ Thread.currentThread () . getname ());
C.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
公共静态类R3实现Runnable {
@Override
公共空间run () {
尝试{
C.acquire ();
System.out.println (“3”+ Thread.currentThread () . getname ());
A.release ();
}捕捉(异常e) {
e.printStackTrace ();
}
}
}
}
