[英]Java multi-threading - Find max-element in list with a Fork-Join approach
I'm brushing up on my multi-threading skills in Java and implemented this simple divide&conquer approach to find the max-element in a list, using RecursiveTask from java.util.concurrent.ForkJoinTask 我正在研究Java中的多线程技巧,并使用java.util.concurrent.ForkJoinTask中的RecursiveTask实现这种简单的分而治之的方法来查找列表中的max-element。
public static void main(String[] args){
new Multithreading().compute();
}
public void compute(){
Integer[] ints = {3,2,5,7,1};
List<Integer> list = Arrays.asList(ints);
ForkJoinPool pool = new ForkJoinPool();
Integer result = pool.invoke(new DividerTask(list));
System.out.println(result);
}
class DividerTask extends RecursiveTask<Integer>{
List<Integer> list;
public DividerTask(List list){
this.list = list;
}
@Override
protected Integer compute(){
if(list.size() > 2){
int mid = list.size()/2;
List<Integer> list1 = list.subList(0,mid);
List<Integer> list2 = list.subList(mid,list.size());
DividerTask dt1 = new DividerTask(list1);
dt1.fork();
DividerTask dt2 = new DividerTask(list2);
dt2.fork();
Integer res1 = dt1.join();
Integer res2 = dt2.join();
return (res1 > res2 ? res1 : res2);
}
if(list.size() == 2){
Integer res1 = list.get(0);
Integer res2 = list.get(1);
return (res1 > res2 ? res1 : res2);
}
return list.get(0);
}
}
How would you approach this? 你会怎么做? What other multi-threaded solutions would you consider?
您会考虑哪些其他多线程解决方案?
Follow the example in RecursiveTask: 按照RecursiveTask中的示例进行操作:
dt1.fork()
return dt2.compute() + dt1.join()
The double join() you are doing results in both computes waiting. 你正在做的双连接()会导致两个计算器等待。 Use the dt2.compute() to force the current thread to keep moving.
使用dt2.compute()强制当前线程继续移动。
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