pandasmultiprocessingpandas-ta

using multiproccesing with the pandas-ta library


Im trying to use the multiproccesing feature of pandas-ta, an technical analysis library. The example is descriped here https://pythonrepo.com/repo/twopirllc-pandas-ta-python-deep-learning#multiprocessing

But i cant get the example too work, the errormessage gives a clear hint to what could be wrong "An attempt has been made to start a new process before the current process has finished its bootstrapping phase."

I need help deciphering the error message, what im a doing wrong in this example?


df1 = pd.DataFrame() # Empty DataFrame

# Load data
df1 = pd.read_csv("I Provide data further down.csv", sep=",")

def cleanUp(frame):
    frame = frame.iloc[:, :6]
    frame.columns = ['Time', 'Open', 'High', 'Low', 'Close', 'Volume']
    frame[['Open', 'High', 'Low', 'Close', 'Volume']] = frame[['Open', 'High', 'Low', 'Close', 'Volume']].astype(float)
    #frame.Time = pd.to_datetime(frame.Time, unit='ms')
    return frame

df = cleanUp(df1)

df.set_index(pd.DatetimeIndex(df["datetime"]), inplace=True)

df.ta.strategy()

df.ta.strategy(verbose=True)

df.ta.strategy(timed=True)

# Choose the number of cores to use. Default is all available cores.
# For no multiprocessing, set this value to 0.
df.ta.cores = 4

print(df.columns)
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 125, in _main
    prepare(preparation_data)
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 236, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 287, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\runpy.py", line 268, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\runpy.py", line 97, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\jeppe\PycharmProjects\pandas-ta-trial\main.py", line 47, in <module>
    df.ta.strategy()
  File "C:\Users\jeppe\PycharmProjects\test\pandas-ta-trial\lib\site-packages\pandas_ta\core.py", line 725, in strategy
    with Pool(self.cores) as pool:
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\pool.py", line 212, in __init__
    self._repopulate_pool()
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\pool.py", line 303, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\pool.py", line 326, in _repopulate_pool_static
    w.start()
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\context.py", line 327, in _Popen
    return Popen(process_obj)
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\popen_spawn_win32.py", line 45, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 154, in get_preparation_data
    _check_not_importing_main()
  File "C:\Users\jeppe\AppData\Local\Programs\Python\Python39\lib\multiprocessing\spawn.py", line 134, in _check_not_importing_main
    raise RuntimeError('''
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.
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Solution

  • From the stacktrace it looks like your code is running under Windows, and when using multiprocessing code on Windows, it must be guarded by if __name__ == "__main__":

    It would be safer to wrap your code in a main() function, and then call it at the top-level:

    if __name__ == "__main__":
        main()
    

    Same recommendation is given in the error description as well.