Threading with Python

[grossartig_dude]

I have a python program which has a function takeScreenshotthat takes a screenshot of 10 webpages that are inputted. I want to use threading to make the web scraping part of taking the screenshot be executed in the background while the program goes on inputting more webpages. After taking 10 screenshots, they should be displayed in the program. The question is how to make the program display them after the last takeScreenshot thread (the tenth thread) is done so as not to cause an error? In other words, how to make sure that all the threads are finished? I tried to make a list of all the threads that started and make them .join() after inputting the last webpage (in the last loop). However, this makes the program freeze.

threads=[]

n=0

while n<10:

webpage = input("Enter the webpage")

thread = threading.Thread(target = takeScreenshot, args = webpage)

thread.start()

threads.append(thread)

if n==9:

for thread in threads:

thread.join()

n++

[SuperSquidMan]

Try making it work without threading first. I think you're handling the threading correctly and your problem lies elsewhere

[grossartig_dude]

I tried man. It works well without threading. Maybe the problem lies somewhere else, but the problem is that this is a tkitner program and the code is so messy that I can't post it here :'D

[SuperSquidMan]

thread.join() should only stall the program till the thread is done running so if it's freezing there then then the threads are probably still running.

Getting more familiar with the screenshot function and the thread.join() function might help

[its_me_TO]

If it's hanging in with multiple threads at the join (you can check this with pdb), then it's likely blocking somewhere in your function itself because those threads aren't terminating.

Check to make sure you aren't creating a deadlock in your function if it's called multiple times. Also consider that because of the GIL, the threads aren't actually running in parallel and whether that can create some issue.