How to run multiple threads properly

[cyberion1985]

from threading import Thread

import time

def PR01():
    k = 0
    while (k < 25000000):
        k = k + 1
        
def PR02():
    k = 0
    while (k < 25000000):
        k = k + 1        
    
# defining the time now in epoch format
def thetime():
    return int(time.time())
    
print "only start here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<"   

task_start = thetime()

k = 0
while (k < 25000000):
    k = k + 1
    
k = 0
while (k < 25000000):
    k = k + 1


task_end = "%05d" % (thetime() - task_start,)
print("original = " + str(task_end))            

task_start = thetime()
p01 = Thread(name='PR01', target=PR01)
p02 = Thread(name='PR02', target=PR02)

p01.start()
p01.join()

p02.start()
p02.join()

task_end = "%05d" % (thetime() - task_start,)
print("processed 1 = " + str(task_end))    

print "only done here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<"