在Clojure中使用pmap并行化合并排序。程序在结束前会挂起〜1分钟，然后终止

Question

我正在用Clojure编写一个程序，该程序从文本文件10000.txt（具有10k，无符号整数）接受输入。然后，我将该列表传递到我的归类排序函数中（单个线程，2、4、8、16、32线程）。

当我运行该程序时，通过键入“ clojure test.clj”，它会输出每个函数的经过时间，但该程序不会终止。

它像正在等待输入或即将输出其他内容一样挂在那里。然后大约1分钟后，程序最终终止。幕后一定有事发生。输入后终止程序有什么想法/我需要做什么？

程序的输出（终止之前），这是挂起大约1分钟的地方

(use 'clojure.java.io)
(require '[clojure.string :as str])

;Read file and store into numbers, as a string
(def numbers (slurp "10000.txt"))

;Parse the string 'numbers', ignore the spaces 
;and save the result into x1 (a lazy-seq of integers)
(def x1 (map #(Integer/parseInt %) (str/split numbers #"\s+")))

;Function that performs the operation of merge sort algorithm
(defn merge-lists [left right]
  (loop [head [] L left R right]
    (if (empty? L) (concat head R)
        (if (empty? R) (concat head L)
            (if (> (first L) (first R))
              (recur (conj head (first R)) L (rest R))
              (recur (conj head (first L)) (rest L) R))))))

;The other merge-sort functions use pmap to run merge sort in parallel
;Using 1,2,4,8,16,32 threads
(defn naive-merge-sort [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (map naive-merge-sort
                  (split-at (/ (count list) 2) list)))))

(defn parallel-merge-sort-2 [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (pmap naive-merge-sort
                   (split-at (/ (count list) 2) list)))))

(defn parallel-merge-sort-4 [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (pmap parallel-merge-sort-2
                   (split-at (/ (count list) 2) list)))))

(defn parallel-merge-sort-8 [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (pmap parallel-merge-sort-4
                   (split-at (/ (count list) 2) list)))))

(defn parallel-merge-sort-16 [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (pmap parallel-merge-sort-8
                   (split-at (/ (count list) 2) list)))))

(defn parallel-merge-sort-32 [list]
  (if (< (count list) 2) list
      (apply merge-lists
             (pmap parallel-merge-sort-16
                   (split-at (/ (count list) 2) list)))))

;Run each of the merge-sort functions and output their time
(time (naive-merge-sort x1))
(time (parallel-merge-sort-2 x1))
(time (parallel-merge-sort-4 x1))
(time (parallel-merge-sort-8 x1))
(time (parallel-merge-sort-16 x1))
(time (parallel-merge-sort-32 x1))

这是我的10000.txt文件：https ://pastebin.com/5vKXUk1u

我的预期结果是程序在最终时间打印后终止，而不用花1分钟时间终止。

谢谢大家的时间和帮助！

Answer 1

您需要shutdown-agents在最后调用以停止Clojure的线程池。

另请参见clojure.org上的代理和异步操作：

请注意，使用代理会启动非守护程序后台线程池，这将防止JVM关闭。使用shutdown-agents终止这些线程并允许关机。