Question

I’m having a hard time trying to create child processes for every folder in the current directory to execute certain function on them (Python 2.7).

My idea is to:

• First get all the folders with os.listdir(path) and filter the files with os.path.isdir(file_path).
• Count the folders and calculate how many forks are needed, e.g: for 5 folders I’d need 3 forks (2³ – 1 = 7 child processes)

• Iterate through the number of needed forks and in each iteration execute the code for the folders, two at a time, getting their paths from a list containing all the folder paths.

  for counter in needed_forks:
     folder_pid = os.fork()
     if pid:
        some_function(folder_list[counter])
     else:
        some_function(folder_list[counter+1])
  

I can’t get any good output mostly due to, I think, one index of the folder_list repeating in each iteration.
Any help is really appreciated, I’m rushing on this assignment, trying to learn multiprocessing and Python at once.

Thanks.

Answer 1

Why not just have one process keep forking? Then you don’t have to try to calculate the number of forks to use:

for d in directories:
    if os.fork():
        # parent
        continue
    else:
        # child
        # handle d...
        break # don't keep going

Of course, I’d question the wisdom of using fork to handle directories this way…