Multiprocessing.Process 没有启动而没有任何错误

Question

下面是我的演示：

Thread xxx:
    import xxx
    import xxxx

    def test_process1(hostname,proxy_param):
        # just never run
        try:                             # breakpoint 0
            with open("/xxx","w+") as f: # breakpoint 1
                f.write("something")
        except Exception as e:
            pass # just never run  breakpoint 3
    def test():
        try:
            a = Process(target=test_process1, args=(hostname,proxy_param))
            a.start()
            a.join() # you are blocking here. test_process1 not working and never quit
        except Exception as e: 
            pass # breakpoint 4

function test_process1从未运行。 没有错误，没有断点。

测试function代码在一个大项目中，这里有一个demo。

Answer 1

希望。 这段代码有帮助。

工人列表将根据正在使用的进程数进行划分。

带有 ManagerList 的示例代码。

from subprocess import PIPE, Popen
from multiprocessing import Pool,Pipe
from multiprocessing import Process, Queue, Manager

def child_process(child_conn,output_list,messenger):
    input_recvd = messenger["input"]
    output_list.append(input_recvd)
    print(input_recvd)
    child_conn.close()

def parent_process(number_of_process=2):
    workers_inputs = [{"input":"hello"}, {"input":"world"}]
    with Manager() as manager:
        processes        = []
        output_list      = manager.list()  # <-- can be shared between processes.
        parent_conn, child_conn = Pipe()
        for single_id_dict in workers_inputs:
            pro_obj             = Process(target=child_process, args=(child_conn,output_list,single_id_dict))  # Passing the list
            pro_obj.start()
            processes.append(pro_obj)
        for p in processes:
            p.join()
        output_list = [single_feature for single_feature in output_list]
    return output_list

parent_process()

OUTPUT：

hello

world

['hello', 'world']

ManagerList 对于从各种并行进程中获取 output 很有用，它就像一个内置的队列机制，易于使用且不会出现死锁。