Python 多处理，不能 pickle thread.lock (pymongo)

Question

我有一个 class 方法如下：

def get_add_new_links(self, max_num_links):
    self.get_links_m2(max_num_links)
    processes = mp.cpu_count()
    pool = mp.Pool(processes=processes)
    func = partial(worker, self)
    with open(os.path.join(self.report_path, "links.txt"), "r") as f:
        reports = pool.map(func, f.readlines())
    pool.close()
    pool.join()

其中 get_links_m2 是另一种创建文件“links.txt”的方法。工人是：

def worker(obje, link):
    doc, rep = obje.get_info_m2(link)
    obje.add_new_active(doc, sure_not_exists=True)
    return rep

方法 get_info_m2 访问 link 并提取一些信息。 add_new_active 方法将信息添加到 MongoDB.

我的代码可能有什么问题？当我运行它我得到这个错误（和回溯）：

File "controller.py", line 234, in get_add_new_links

reports = pool.map(func, f.readlines())   File "/home/vladimir/anaconda3/lib/python3.5/multiprocessing/pool.py", line

260, in map

return self._map_async(func, iterable, mapstar, chunksize).get()   File "/home/vladimir/anaconda3/lib/python3.5/multiprocessing/pool.py",

line 608, in get

raise self._value   File "/home/vladimir/anaconda3/lib/python3.5/multiprocessing/pool.py", line

385, in _handle_tasks

put(task)   File "/home/vladimir/anaconda3/lib/python3.5/multiprocessing/connection.py",

line 206, in send

self._send_bytes(ForkingPickler.dumps(obj))   File "/home/vladimir/anaconda3/lib/python3.5/multiprocessing/reduction.py",

line 50, in dumps

cls(buf, protocol).dump(obj) TypeError: can't pickle _thread.lock objects

Answer 1

如the docs所述：

永远不要这样做：

client = pymongo.MongoClient()

# Each child process attempts to copy a global MongoClient
# created in the parent process. Never do this.
def func():
  db = client.mydb
  # Do something with db.

proc = multiprocessing.Process(target=func)
proc.start()

相反，必须在 worker 函数中初始化客户端。

Python 多处理，不能 pickle thread.lock (pymongo)

Python multiprocessing, can't pickle thread.lock (pymongo)

python

multithreading

python-multiprocessing