在Scala循环中为多线程创建ForkJoinTask时出现的奇怪行为

Question

该作业是转换src数组中的值并将新值写入dst数组。

当我在while循环

val height: Int = 4; 
val numTasks: Int = 2; 

var tasks = scala.collection.mutable.ListBuffer.empty[ForkJoinTask[Unit]] 

val jump: Int = src.height/numTasks 
var from: Int = 0; 

while (from < height) { 
    val end: Int = height.min(from + jump); 
    val t: ForkJoinTask[Unit] = task { 
    run(src, dst, from, end) // (2,2), (2,1), what is happening? 
    } 
    from = end 
} 

for (t <- tasks.toList) { 
    t.join() 
} 

创建的ForkJoinTasks然后奇怪的是，在运行函数采用（来自，结束）的参数的值作为（2,2）。但是，如果我手动将它分成两个任务，那么它正常工作，如（0,1）和（1,2）。

val t1 = task { 
    run(src, dst, 0, height/2); // (0, 1) 
} 
val t2 = task { 
    run(src, dst, height/2, height); // (1, 2) 
} 

t1.join() 
t2.join() 

我很难弄清楚发生了什么事情。这是我第一个Scala程序，所以我可能会错过一些非常微不足道的东西。任何意见将不胜感激。

谢谢。

Answer 1

删除引用为src或DST代码似乎确定为回报范围

import shapeless.PolyDefns.~> 
import shapeless.{ HList, HNil } 
import io.netty.util.internal.chmv8.ForkJoinTask 

object main extends App { 

    val height: Int = 4; 
    val numTasks: Int = 2; 

    var tasks = scala.collection.mutable.ListBuffer.empty[ForkJoinTask[Unit]] 

    val jump: Int = height/numTasks 
    var from: Int = 0; 

    while (from < height) { 
    val end: Int = height.min(from + jump); 
    val t: ForkJoinTask[Unit] = { 
     run(from, end) // (2,2), (2,1), what is happening? 
    } 
    from = end 
    } 

    for (t <- tasks.toList) { 
    t.join() 
    } 


    def run (from: Int, end:Int) ={ 
    println(s"$from $end") 
    null 
    } 

}