title: How can I fix "TypeError: cannot serialize '_io.BufferedReader' object" error when trying to multiprocess
body: <p>I'm trying to switch the threading in my code to multiprocessing to measure its performance and hopefully achieve better brute-forcing potential as my program is meant to brute-force password protected .zip files. But whenever I try to run the program I get this:</p>
  
  <pre class="lang-none prettyprint-override"><code>BruteZIP2.py -z "Generic ZIP.zip" -f  Worm.txt
  Traceback (most recent call last):
    File "C:\Users\User\Documents\Jetbrains\PyCharm\BruteZIP\BruteZIP2.py", line 40, in &lt;module&gt;
      main(args.zip, args.file)
    File "C:\Users\User\Documents\Jetbrains\PyCharm\BruteZIP\BruteZIP2.py", line 34, in main
      p.start()
    File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\multiprocessing\process.py", line 112, in start
  self._popen = self._Popen(self)
    File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\multiprocessing\context.py", line 223, in _Popen
  return _default_context.get_context().Process._Popen(process_obj)
    File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\multiprocessing\context.py", line 322, in _Popen
  return Popen(process_obj)
    File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\multiprocessing\popen_spawn_win32.py", line 65, in __init__
  reduction.dump(process_obj, to_child)
    File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\multiprocessing\reduction.py", line 60, in dump
  ForkingPickler(file, protocol).dump(obj)
  TypeError: cannot serialize '_io.BufferedReader' object
  </code></pre>
  
  <p>I did find threads that had the same issue as I did but they were both unanswered/unsolved. I also tried inserting <code>Pool</code> above <code>p.start()</code> as I believe this was caused due to the fact that I am on a Windows-based machine but it was no help. My code is as follows:</p>
  
  <pre><code>  import argparse
    from multiprocessing import Process
    import zipfile
  
    parser = argparse.ArgumentParser(description="Unzips a password protected .zip by performing a brute-force attack using either a word list, password list or a dictionary.", usage="BruteZIP.py -z zip.zip -f file.txt")
    # Creates -z arg
    parser.add_argument("-z", "--zip", metavar="", required=True, help="Location and the name of the .zip file.")
    # Creates -f arg
    parser.add_argument("-f", "--file", metavar="", required=True, help="Location and the name of the word list/password list/dictionary.")
    args = parser.parse_args()
  
  
    def extract_zip(zip_file, password):
        try:
            zip_file.extractall(pwd=password)
            print(f"[+] Password for the .zip: {password.decode('utf-8')} \n")
        except:
            # If a password fails, it moves to the next password without notifying the user. If all passwords fail, it will print nothing in the command prompt.
            print(f"Incorrect password: {password.decode('utf-8')}")
            # pass
  
  
    def main(zip, file):
        if (zip == None) | (file == None):
            # If the args are not used, it displays how to use them to the user.
            print(parser.usage)
            exit(0)
        zip_file = zipfile.ZipFile(zip)
        # Opens the word list/password list/dictionary in "read binary" mode.
        txt_file = open(file, "rb")
        for line in txt_file:
            password = line.strip()
            p = Process(target=extract_zip, args=(zip_file, password))
            p.start()
            p.join()
  
  
    if __name__ == '__main__':
        # BruteZIP.py -z zip.zip -f file.txt.
        main(args.zip, args.file)
  </code></pre>
  
  <p>As I said before, I believe this is happening mainly because I am on a Windows-based machine right now. I shared my code with a few others who were on Linux based machines and they had no problem running the code above. </p>
  
  <p>My main goal here is to get 8 processes/pools started to maximize the number of attempts done compared to threading, but due to the fact that I cannot get a fix for <code>TypeError: cannot serialize '_io.BufferedReader' object</code> message I am unsure on what to do here and how can I go on to fix it. Any assistance would be appreciated.</p>