Question

我尝试通过拆分它来检查元素是否在字符串中：

`public class ParallelSearchComment扩展了RecursiveTask { private static final long serialVersionUID = 1L;

int lo; 
int hi; 
String com;
String query;
int T;

ParallelSearchComment(String c, int l, int h, String q, int Treshold){
    com=c;
    lo=l;
    hi=h;
    query=q;
    T=Treshold;
}

private int findMiddle(String text){ // Only split at whitespace chars (or some words would be missed) 

    int middle = lo + ((hi - lo)/2);
    int i= middle;                                                            
    for (i = middle; i != hi && com.charAt(middle) != ' ' && i-middle <= query.length()+1; i++){

    }  
    middle = i;
    return middle;
}

@Override
protected Boolean compute() {
    int middle = findMiddle(com);
    if (hi - lo < T || hi-middle <= query.length()) {//hi-middle <= query.length()
        return com.substring(lo, hi).contains(query);
    } else {

        ParallelSearchComment left = new ParallelSearchComment(com, lo, middle, query, T);
        ParallelSearchComment right = new ParallelSearchComment(com, middle, hi, query, T);

        left.fork();
        boolean resRight = right.compute();
        boolean resLeft = left.join();

        return resRight || resLeft;
    }

}

static boolean ParallelSearchComment(String c, String query, int T,int p) {
    final ForkJoinPool fjPool = new ForkJoinPool(p);
    ParallelSearchComment t = new ParallelSearchComment(c, 0, c.length(), query, T);
    return fjPool.invoke(t);
}

`

Answer 1

问题是，每次调用ForkJoinPool时，您都要创建一个新的ParallelSearchComment实例。相反，您应该创建一个ForkJoinPool并在整个应用程序中使用。

Answer 2

由于您的代码段未显示如何调用static boolean ParallelSearchComment，因此我假设它已用于初始化您的搜索。另外，我假设您仅从main触发了一次搜索。

这样，您传入的并行度值或p很可能高于当前JVM堆可以处理的值。看看当你把它减少到5或10时会发生什么。

为什么我的代码创建了很多线程（java.lang.OutOfMemoryError：无法创建新的本机线程）

2 个答案: