CODEWITHSUNDEEP
pythonmultithreadingpython-3.x
Setti7
Setti7

Reputation: 149

RuntimeError: threads can only be started once for a beginner

This is for my first program. I am trying to put this loading animation in a while loop, but it gives this error after the second "f.start()". As I don't understand much about threads, the "help" I could find on Google was not helpful at all, which involved long codes with class creation and everything. Can somebody help me understand what I could do here?

I copied the animation code from here: Python how to make simple animated loading while process is running

import itertools
import threading
import time
import sys


#here is the animation
def animate():
    for c in itertools.cycle(['|', '/', '-', '\\']):
        if done:
            break
        sys.stdout.write('\rloading ' + c)
        sys.stdout.flush()
        time.sleep(0.25)
    sys.stdout.write('\rDone!     ')

t = threading.Thread(target=animate)

while True:
    done = False
    user_input = input('Press "E" to exit.\n Press"S" to stay.')
    if user_input is "E":
        break
    elif user_input is "S":
        # Long process here
        t.start()
        time.sleep(5)
        done = True
        time.sleep(1)
        print("\nThis will crash in 3 seconds!")
        time.sleep(3)
        break


# Another long process here
t.start()
time.sleep(5)
done = True

Upvotes: 1

Views: 6781

Answers (1)

tdelaney
tdelaney

Reputation: 77347

As the error says, a thread can only be started once. So, create a new thread instead. Notice also that I use join to wait for the old thread to stop.

import itertools
import threading
import time
import sys


#here is the animation
def animate():
    for c in itertools.cycle(['|', '/', '-', '\\']):
        if done:
            break
        sys.stdout.write('\rloading ' + c)
        sys.stdout.flush()
        time.sleep(0.25)
    sys.stdout.write('\rDone!     ')

t = threading.Thread(target=animate)

while True:
    done = False
    user_input = input('Press "E" to exit.\n Press"S" to stay.')
    if user_input is "E":
        break
    elif user_input is "S":
        # Long process here
        t.start()
        time.sleep(5)
        done = True
        t.join()
        print("\nThis will crash in 3 seconds!")
        time.sleep(3)
        break


# Another long process here
done = False
t = threading.Thread(target=animate)
t.start()
time.sleep(5)
done = True

Upvotes: 1

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