Print character while copying big folder

Question

I have this function trying to print additional '.' every second while it's copying a big folder (~3GB) from one place to another:

def copy_folder(source, destination):
    print 'copying',
    while shutil.copytree(src=source, dst=destination):
        print '.',
        time.sleep(1)

but when I call the function:

source = 'source_folder'
destination = 'destination_folder'
copy_folder(source=source, destination=destination)

it's copying perfectly fine the whole folder but it does NOT print '.' at all.

Do I need to use threads?

Answer 1

Threading in Python is pretty simple:

import sys, shutil, time, threading

class CopyThread(threading.Thread):
    def __init__(self, source, destination):
        super(CopyThread, self).__init__()

        self.source = source
        self.destination = destination

    def run(self):
        time.sleep(5)  # Delete me later on, I'm just here to slow things down
        return shutil.copytree(src=self.source, dst=self.destination)

if __name__ == '__main__':
    thread = CopyThread('source_folder', 'destination_folder')
    thread.start()

    while thread.is_alive():
        sys.stdout.write('.')
        sys.stdout.flush()

        time.sleep(1)

    thread.join()

Just subclass threading.Thread and override run(). After that, call .start() on an instance of that class and you have a thread.

Answer 2

copytree will copy the entire tree so the while loop won't run until the copy is complete and the return value can be evaluated.

My python is rusty, but I'll give an idea of how to implement the thread (inspired by the code found here).

def copy_folder(source, destination):
    self.iscopying = True        
    self.thread = threading.Thread(name="GPS Data", target=self.thread_run)
    self.thread.setDaemon(True)
    self.thread.start()
    shutil.copytree(src=source, dst=destination)
    self.iscopying = false


def thread_run(self):
    while self.iscopying:
        print '.'
        time.sleep(1)

Essentially, create a flag that tells the thread when the copying is happening and then set it to false when the copy is complete.