Question

我是python中的线程新手（实际上是python的新手）。我编写了一些排序函数来测试python，并认为并行运行所有三种排序算法进行实时比较是个好主意。但是，当我按顺序运行排序函数时，程序所需的时间比线程所有三种算法的时间要少。为什么会这样？线程是不是意味着不能像这些一样快速加速？

import random
import time
import copy
import BubbleSort
import SelectionSort
import InsertionSort
import threading

# MAX contains the amount of numbers to sort
from MAX import MAX

def generateRandomList(List):
    """
    Generates a Random Usorted List
    """

    for i in range(MAX + 1):
        List.append(random.randrange(0, MAX + 1))

def displayList(List):
    """
    Displays a List until the first hundred values
    """

    for i in range(100):
        print List[i]

def isSorted(List):
    """
    Check if a List is sorted
    """

    for i in range(MAX):
        if List[i] > List[i + 1]:
            return False
    return True

def callSort(SortFunction, SortName):
    """
    Calls the function and records its execution time
    """

    StartTime = time.time()
    CopyList = copy.deepcopy(List)
    SortFunction(CopyList)
    Sorted = isSorted(CopyList)
    print ("%s Sort: %s seconds" % (SortName, time.time() - StartTime))
    print "IsSorted: ", Sorted
    print

class ThreadedSort(threading.Thread):
    """
    Class for running Sorting algorithms in a threaded fashion
    """

    def __init__(self, SortFunction, SortName):
        threading.Thread.__init__(self)
        self.SortFunction = SortFunction
        self.SortName = SortName

    def run(self):
        callSort(self.SortFunction, self.SortName)

# Get the list
List = []
generateRandomList(List)

# Store sorting algorithms for easier access
SortFunctions = {
                    "Bubble" : BubbleSort.bubbleSort,
                    "Selection" : SelectionSort.selectionSort,
                    "Insertion" : InsertionSort.insertionSort
                }

# Store threads in a list
SortingList = []

""" Begin Sorting """

# Threaded Sorting
for SortType in SortFunctions:
    Sorting = threading.Thread(target = callSort, args = (SortFunctions[SortType], SortType))
    SortingList.append(Sorting)
    Sorting.start()

print "Threaded sorting has Begun..."
print
for Item in SortingList:
    print Item
print

"""
# Sequential 
print "Sequential sorting has Begun..."
print
for SortType in SortFunctions:
    callSort(SortFunctions[SortType], SortType)
"""

""" End - Sorting """

这是我的代码。请帮助：）

为什么线程排序函数比在python中顺序运行它们要慢？

0 个答案: