René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"multiprocessing.Pool map hangs","articleBody":"# Bug report\n\n### Bug description:\n\nQ:\nRun the following code, sometimes subprogres that is created by [class A's Pool or class B's Pool] is going to sleeping status, and there is not any error log output.\nBut code（#3 or #4）run success, code(#1 or #2) is not run,The reason is pool.close() and pool.join() is not writed in source code?\n\n```python\ntest.py\n\nfrom multiprocessing import Pool\nimport os\nfrom test_common import *\n\nclass Test:\n    def __init__(self):\n        self.A = A()\n        self.B = B()\n\n    def run(self):\n        data_list = list(range(10001, 11984))\n\n        a_list = self.A.run(data_list)\n        print(\"self.A.run end\") #1\n\n        new_list = self.B.run(data_list, a_list)\n        print(\"self.B.run end\") #2\n\n\ndef main():\n    run_module = Test()\n    run_module.run()\n\nif __name__ == '__main__':\n    main()\n\n---------------------------------------------\ntest_common.py\n\nimport os\nimport multiprocessing\nfrom multiprocessing import Pool\nimport io\nimport datetime\nimport time\n\nclass A:\n    def __init__(self):\n        pass\n\n    def run(self, data_list):\n        a_list = []\n        for item in data_list:\n            file_path = \"{}/{}.aaa\".format(\"/tmp/aaa\", item)\n            a_list.append(file_path)\n\n        pool_size = 1\n        pool = Pool(pool_size)\n        pool.map(methodA, a_list)\n        print(\"A#run end\") #3\n        return a_list\n\n\ndef methodA(file_path):\n    if os.path.isfile(file_path):\n        return\n    # other code\n\nclass B:\n    def __init__(self):\n        pass\n\n    def run(self, data_list, a_list):        \n        b_list = []\n        for item in data_list:\n            b_path = \"{}/{}.bbb\".format(\"/tmp/bbb\", item)\n            b_list.append(b_path)\n\n        pool_size = 1\n        pool = Pool(pool_size)\n        pool.map(methodB, b_list)\n \n        print(\"B#run end\") #4\n        return b_list\n\ndef methodB(b_path):\n    if os.path.isfile(b_path):\n        return\n    # other code\n```\n\n\n### CPython versions tested on:\n\n3.10\n\n### Operating systems tested on:\n\nLinux","author":{"url":"https://github.com/wdxal","@type":"Person","name":"wdxal"},"datePublished":"2024-08-12T06:12:29.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/122930/cpython/issues/122930"}