如何在并行下载文件时正确使用"Pool"？

Question

我想使用从 youtube 并行下载视频，但我的代码以异常“PicklingError”结尾。你能帮忙写代码吗，请问代码应该如何。

另一个固定变体：

import sys
#from pathos.multiprocessing import ProcessingPool as Pool
from multiprocessing import Pool
from pytube import YouTube
from youtubeMultiDownloader import UiMainWindow
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QFileDialog


class YouTubeInstance:
    def __init__(self, path):
        self.youtube = YouTube
        self.path = path
        #self.ui_obj = ui_obj

    def download_file(self, url):
        self.youtube(url).streams.get_highest_resolution().download(self.path)
        #self.ui.ui.youtube_outputs.setText(f'Video \'{self.youtube.title}\' has been downloaded successfully!')


class YouTubeMultiDownloader(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.pool = Pool
        self.ui = UiMainWindow()
        self.ui.setup_ui(self)
        self.path_to_dir = None
        self.urls = None

    def _get_urls_from_form(self):
        self.urls = self.ui.youtube_urls.toPlainText().split('\n')
        return len(self.urls)

    def choose_directory(self):
        self.path_to_dir = str(QFileDialog.getExistingDirectory(self, "Select Directory"))

    def run_multi_downloads(self):
        youtube = YouTubeInstance(self.path_to_dir)
        self.pool(self._get_urls_from_form()).map(youtube.download_file, self.urls)


if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    application = YouTubeMultiDownloader()
    application.show()
    sys.exit(app.exec_())

更新：

我的ui :)

错误 1 已修复：

错误 2 已修复：

实际错误 3：

Answer 1

你的立场错了。查看 multiprocessing 模块文档。正如它所说，调用 Pool 方法是针对运行同时（并行）相同函数的多个实例。所以调用 Pool 方法你想要多少数字，同时你的方法没有任何参数，不带任何参数调用它：

with Pool(5) as p:
    print(p.map(YouTubeMultiDownloader))

创建5个并行实例。您可以更改代码以改进您的错误。

如何在并行下载文件时正确使用"Pool"？

How to right use "Pool" in parallel downloading files?

python-3.x

multiprocessing

python-multiprocessing

multiprocess