IBM API的Python多处理错误(Q经验) [英] Python Multiprocessing Error with IBM API (Q Experience)

问题描述

我正在尝试使用IBM Q Experience API，并且我安装了该库并编写了快速测试代码.起初，它找不到模块.然后，我添加了整个sys内容.诚然，我只是从stackoverflow帖子中复制了该内容，所以可能是问题所在.无论如何，我遇到了运行时错误"，该错误导致了python multiprocessing lib. IBM Q的社区不大，因此经过一段时间的研究后我什么也找不到.我完全不熟悉多处理，线程等，因此我想仅仅看到代码和错误会比我能做的任何解释都要好.预先感谢.

I'm trying to use the IBM Q Experience API and I installed the library and wrote a quick test code. At first, it couldn't find the module. Then, I added the whole sys thing. Admittedly, I just copied that from a stackoverflow post so that may be the problem. Anyways, I got "RunTime Error" which leads to the python multiprocessing lib. The IBM Q doesn't have a big community, so I couldn't find anything after researching a little while. I'm completely unfamiliar with multiprocessing, threading, etc, so I imagine just seeing the code and error will be better than anything I can do to explain. Thanks in advance.

import sys
sys.path.append("../../")

from qiskit import QuantumProgram

#visualization
from tools.visualization import plot_histogram

#set up registers
qp = QuantumProgram()
q = qp.create_quantum_register("q", 3)
c = qp.create_classical_register("c", 3)

#define our circuit
threeQ = qp.create_circuit("threeQ", [q], [c])
threeQ.measure(q[0], c[0])
threeQ.measure(q[1], c[1])
threeQ.measure(q[2], c[2])

#run
result = qp.execute(["threeQ"])

#plot
plot_histogram(result.get_counts("threeQ"))

我得到的错误(抱歉，很长):

The error I get (sorry, it's long):

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 106, in spawn_main
    exitcode = _main(fd)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 115, in _main
    prepare(preparation_data)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 226, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 278, in _fixup_main_from_path
    run_name="__mp_main__")
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 254, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\Everybody\firstquantum.py", line 21, in <module>
    print(qp.execute(["threeQ"]))
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1413, in execute
    result = self.run(qobj, wait=wait, timeout=timeout)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1232, in run
    timeout=timeout)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1315, in _run_internal
    job_processor.submit()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_jobprocessor.py", line 118, in submit
    future = executor.submit(run_backend, q_job)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 454, in submit
    self._start_queue_management_thread()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 415, in _start_queue_management_thread
    self._adjust_process_count()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 434, in _adjust_process_count
    p.start()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\context.py", line 212, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\context.py", line 313, in _Popen
    return Popen(process_obj)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\popen_spawn_win32.py", line 34, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 144, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 137, in _check_not_importing_main
    is not going to be frozen to produce an executable.''')
RuntimeError:
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 106, in spawn_main
    exitcode = _main(fd)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 115, in _main
    prepare(preparation_data)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 226, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 278, in _fixup_main_from_path
    run_name="__mp_main__")
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 254, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\Everybody\firstquantum.py", line 21, in <module>
    print(qp.execute(["threeQ"]))
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1413, in execute
    result = self.run(qobj, wait=wait, timeout=timeout)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1232, in run
    timeout=timeout)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_quantumprogram.py", line 1315, in _run_internal
    job_processor.submit()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\site-packages\qiskit\_jobprocessor.py", line 118, in submit
    future = executor.submit(run_backend, q_job)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 454, in submit
    self._start_queue_management_thread()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 415, in _start_queue_management_thread
    self._adjust_process_count()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\concurrent\futures\process.py", line 434, in _adjust_process_count
    p.start()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\process.py", line 105, in start
    self._popen = self._Popen(self)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\context.py", line 212, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\context.py", line 313, in _Popen
    return Popen(process_obj)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\popen_spawn_win32.py", line 34, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 144, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 137, in _check_not_importing_main
    is not going to be frozen to produce an executable.''')
RuntimeError:
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 106, in spawn_main
    exitcode = _main(fd)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 115, in _main
    prepare(preparation_data)
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 226, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\multiprocessing\spawn.py", line 278, in _fixup_main_from_path
    run_name="__mp_main__")
  File "C:\Users\Everybody\AppData\Local\Programs\Python\Python35\lib\runpy.py", line 254, in run_path
ERROR

推荐答案

这是Windows上Python中多线程的普遍问题.解决方案是将顶级代码放在 if __name__ =="__main __" 块中，如下所示:

This is a general issue with multi-threading in Python on Windows. The solution is to put your top-level code in an if __name__ == "__main__" block, as in:

if __name__ == '__main__':
    <your code here>

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