我正在尝试创建各种单例模式并使用数百万个线程检查中断。我希望这能引导我最终实现比尔·皮尤(Bill Pugh)。但我什至无法打破经典。
单例:之前尝试过一百万个线程，所有线程都具有相同的哈希码。所以我让它 hibernate 10 秒，这样两个线程都肯定会进入空检查条件，但一切都令人沮丧。
package demo2;
public class Singleton {
private static Singleton soleInstance = null;
private Singleton() throws InterruptedException {
}
public static Singleton getInstance() throws InterruptedException {
if (soleInstance == null) {
Thread.sleep(10000);
soleInstance = new Singleton();
}
return soleInstance;
}
}
测试类:
package demo2;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.stream.Collectors;
class Test {
public int makeSingleton() throws InterruptedException {
Singleton s = Singleton.getInstance();
return s.hashCode();
}
public static void main(String[] args) throws InterruptedException, ExecutionException {
Test t = new Test();
ExecutorService executor = Executors.newFixedThreadPool(2);
List<Integer> list = new ArrayList<>();
for (int i = 0; i < 2; i++) {
Future<Integer> future = executor.submit(new Callable<Integer>() {
public Integer call() throws InterruptedException {
return t.makeSingleton();
}
});
list.add(future.get());
}
executor.shutdown();
List<Integer> list2 = list.stream().distinct().collect(Collectors.toList());
System.out.println(list2);
}
}
我该如何破解它？
最佳答案
下面提到的代码可以工作。
更改您的代码。可能您仅在方法内部调用 get，并且它正在等待获取结果并且循环计数不会增加。
ExecutorService executor = Executors.newFixedThreadPool(2);
List<Future<Integer>> list = new ArrayList<Future<Integer>>();
for (int i = 0; i < 5; i++) {
Future<Integer> future = executor.submit(new Callable<Integer>() {
public Integer call() throws InterruptedException {
return Singleton.getInstance().hashCode();
}
});
list.add(future);
}
executor.shutdown();
Set<Integer> output = new HashSet<Integer>();
for(Future<Integer> future : list){
output.add(future.get());
}
System.out.println(output);
关于java - 无法打破经典的延迟初始化单例，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42743444/