Showing Progress Bar while program is in execution using python

Question

I want to show simple dots while my program copies the files. I have found the code like:

for i in range(10):
 print '.',
 time.sleep(1)

But this will execute ten times as it is predefined and the task to copy will execute after or before this loop based on the location I have placed my line to copy the files using shutil.copy().

I want that the files should be copied and in parallel the progress should be shown and when the files are copied, the progress should exit.

Answer 1

Ahmed has shown how to view the dots as they are printed, but has not addressed the 'parallel' aspect.

Here is one approach, which uses the threading module to print the dots in a separate thread while the main thread does the copying.

import sys
import threading

class ProgressBar(threading.Thread):
 """
 In a separate thread, print dots to the screen until terminated.
 """

 def __init__(self):
 threading.Thread.__init__(self)
 self.event = threading.Event()

 def run(self):
 event = self.event # make local
 while not event.is_set():
 sys.stdout.write(".")
 sys.stdout.flush()
 event.wait(1) # pause for 1 second
 sys.stdout.write("n")

 def stop(self):
 self.event.set()

Before starting the copy -

 progress_bar = ProgressBar()
 progress_bar.start()

When the copy is finished -

 progress_bar.stop()
 progress_bar.join()

Answer 2

Stdout is buffered, meaning it will wait for a newline, or for some large amount of output, before actually outputting the characters to the screen. Use the flush method to force it to be output now. Writing to sys.stdout directly also lets you avoid the space that a print-comma gives you:

 for i in range(10):
 sys.stdout.write(".")
 sys.stdout.flush()
 time.sleep(1)
 sys.stdout.write("n")

Comments

for i in range(10):
 sys.stdout.write(".")
 sys.stdout.flush()
 time.sleep(1)
 sys.stdout.write("n")

shutil.copytree("pack", "/lxc/pack")

But Here, the loop will first print the progress dots and then it will copy the directory. But I want that these two tasks should run simultaneously.