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我有一个使用多处理的单元测试。python 3.4 multiprocessing不能与unittest一起工作
从Python 3.2升级到Python 3.4后,出现以下错误。 我无法找到提示,Python内部发生了什么变化以及我必须更改哪些内容,以使代码正常运行。
在此先感谢。
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "C:\Python341_64\lib\multiprocessing\spawn.py", line 106, in spawn_main
exitcode = _main(fd)
File "C:\Python341_64\lib\multiprocessing\spawn.py", line 116, in _main
self = pickle.load(from_parent)
EOFError: Ran out of input
Error
Traceback (most recent call last):
File "D:\test_multiproc.py", line 46, in testSmallWorkflow
p.start()
File "C:\Python341_64\lib\multiprocessing\process.py", line 105, in start
self._popen = self._Popen(self)
File "C:\Python341_64\lib\multiprocessing\context.py", line 212, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
File "C:\Python341_64\lib\multiprocessing\context.py", line 313, in _Popen
return Popen(process_obj)
File "C:\Python341_64\lib\multiprocessing\popen_spawn_win32.py", line 66, in __init__
reduction.dump(process_obj, to_child)
File "C:\Python341_64\lib\multiprocessing\reduction.py", line 59, in dump
ForkingPickler(file, protocol).dump(obj)
TypeError: cannot serialize '_io.TextIOWrapper' object
继示例代码,我怎么能重现错误:
import shutil
import traceback
import unittest
import time
from multiprocessing import Process
import os
class MyTest(unittest.TestCase):
#---------------------------------------------------------------------------
def setUp(self):
self.working_dir = os.path.join(os.environ["TEMP"], "Testing")
os.mkdir(self.working_dir)
#---------------------------------------------------------------------------
#---------------------------------------------------------------------------
def tearDown(self):
try:
time.sleep(5)
shutil.rmtree(self.working_dir, ignore_errors=True)
except OSError as err:
traceback.print_tb(err)
#---------------------------------------------------------------------------
#---------------------------------------------------------------------------
def info(self, title):
print(title)
print('module name:', __name__)
if hasattr(os, 'getppid'): # only available on Unix
print('parent process:', os.getppid())
print('process id:', os.getpid())
#---------------------------------------------------------------------------
#---------------------------------------------------------------------------
def f(self, name):
self.info('function f')
print('hello', name)
#---------------------------------------------------------------------------
#---------------------------------------------------------------------------
def testSmallWorkflow(self):
self.info('main line')
p = Process(target=self.f, args=('bob',))
p.start()
p.join()
#---------------------------------------------------------------------------
感谢您的非常有用和快速的答案。你说,unittest.Testcase是_不再可选。你对此有更多的信息吗?为什么?也许有一些链接,我可以在这里了解到这一点? – knumskull 2014-09-03 15:38:00
@knumskull我不知道它是否记录在任何地方;我只是通过查看代码来了解它。问题在于'TestCase'在内部使用的'_Outcome'对象包含''result'属性,它是'unittest.runner.TextTestResult'实例。这个类负责将每个测试的结果写入屏幕。它包含对'_io.TextIoWrapper'对象的引用,这些对象不能被腌制。如果我发现本周有一段时间,我可以深入了解3.2到3.4之间的变化,并且可能会提供一个补丁来使TestCase再次变得可用。 – dano 2014-09-03 15:58:50
感谢您的解释。这对我帮助很大。 – knumskull 2014-09-03 16:42:22