Threading in Python 3 homework

[Maxspencer]

Hi All

The following code is my son's homework for an A level he has just begun. The activity he is having trouble with is this:

Activity 2 – Change the following code so that Thread 1 stops after 1 second, Thread 2 after 2 seconds etc.


import time
from threading import Thread

def myfunc(i):
print("\nsleeping 5 sec from thread %d" % i)
time.sleep(5)
print ("\nfinished sleeping from thread %d" % i)

for i in range(10):
t = Thread(target=myfunc, args=(i,))
t.start()


He thought by changing the time.sleep line to: time.sleep(i)
that it should work, but it only gives the result below and only thread 0 seems to stop after 0 seconds with the rest (1-9) all taking about 1 second:

sleeping 5 sec from thread 0

sleeping 5 sec from thread 1
finished sleeping from thread 0

sleeping 5 sec from thread 2

sleeping 5 sec from thread 3
sleeping 5 sec from thread 4



sleeping 5 sec from thread 5

sleeping 5 sec from thread 6

sleeping 5 sec from thread 7

sleeping 5 sec from thread 8

sleeping 5 sec from thread 9

finished sleeping from thread 1

finished sleeping from thread 2

finished sleeping from thread 3

finished sleeping from thread 4

finished sleeping from thread 5

finished sleeping from thread 6

finished sleeping from thread 7

finished sleeping from thread 8

finished sleeping from thread 9

I'm trying to be a cool dad and help him but I can't see where he is going wrong and his online tutor is not contactable. I can't tell you how great it would be if someone could point us in the right direction. He would be asking himself but he is a games thingy in Bradford today. Thanks - Maxspencer

[Mekire]

He thought by changing the time.sleep line to: time.sleep(i)
that it should work, but it only gives the result below and only thread 0 seems to stop after 0 seconds with the rest (1-9) all taking about 1 second.

This seems correct to me.
Each thread stops one second after the previous, yes, but stops a total of i seconds after its creation total.
One thread stops every second.
Think of all the threads being essentially created simultaneously (they are all created in milliseconds). 9 seconds later the thread with i=9 ends.

[Maxspencer]

Thanks Mekire,

I think you might be right. All this time we were looking at this like idiots. Thanks for pointing out our fatal flaw. Cheers, Maxspencer.