使用Python Profiler时出现ImportError，求问题原因及解决方法

问题 #

我尝试用Python的cProfile工具做性能分析，执行命令：

python -m cProfile -m HelloWorld.py

出现了如下错误，cProfile文档里没提到"module specification"或"path"相关内容，想问哪里操作有误？

错误信息 #

Traceback (most recent call last):
  File "<frozen importlib.util>", line 93, in find_spec
AttributeError: module 'HelloWorld' has no attribute '__path__'. Did you mean: '__name__'?

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<frozen runpy>", line 131, in _get_module_details
  File "<frozen importlib.util>", line 95, in find_spec
ModuleNotFoundError: __path__ attribute not found on 'HelloWorld' while trying to find 'HelloWorld.py'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Software\Conda\envs\gpd\Lib\cProfile.py", line 197, in <module>
    main()
    ~~~~^^
  File "C:\Software\Conda\envs\gpd\Lib\cProfile.py", line 186, in main
    runctx(code, globs, None, options.outfile, options.sort)
    ~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Software\Conda\envs\gpd\Lib\cProfile.py", line 21, in runctx
    return _pyprofile._Utils(Profile).runctx(statement, globals, locals,
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                             filename, sort)
                                             ^^^^^^^^^^^^^^^
  File "C:\Software\Conda\envs\gpd\Lib\profile.py", line 64, in runctx
    prof.runctx(statement, globals, locals)
    ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Software\Conda\envs\gpd\Lib\cProfile.py", line 104, in runctx
    exec(cmd, globals, locals)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1, in <module>
  File "<frozen runpy>", line 222, in run_module
  File "<frozen runpy>", line 140, in _get_module_details
ImportError: Error while finding module specification for 'HelloWorld.py' (ModuleNotFoundError: __path__ attribute not found on 'HelloWorld' while trying to find 'HelloWorld.py'). Try using 'HelloWorld' instead of 'HelloWorld.py' as the module name.

解决方法 #

问题出在你用-m参数时传了带.py后缀的文件名，-m要求传入模块名（即去掉.py的文件名），有两种正确的命令写法：

1. 保持模块运行模式，去掉.py后缀：

python -m cProfile -m HelloWorld

2. 直接运行脚本文件，去掉第二个-m：

python -m cProfile HelloWorld.py

原因说明 #

-m参数的作用是让Python将指定模块作为主程序执行，这时候需要传入的是模块名而非带后缀的文件名。你加了.py后，Python会尝试查找名为HelloWorld.py的模块，自然找不到，报错信息最后也明确提示了"Try using 'HelloWorld' instead of 'HelloWorld.py' as the module name"。

内容的提问来源于stack exchange，提问作者Redoute