Use of threading.Thread.join()

Question

I am new to multithreading in python and trying to learn multithreading using threading module. I have made a very simple program of multi threading and i am having trouble

Answer 1

I modified the code so that you will understand how exactly join works. so run this code with comments and without comments and observe the output for both.

val = 0

def increment(msg,sleep_time):
   global val 
   print "Inside increment"
   for x in range(10):
       val += 1
       print "%s : %d\n" % (msg,val)
       time.sleep(sleep_time)

thread1 = threading.Thread(target=increment, args=("thread_01",0.5))
thread2 = threading.Thread(target=increment, args=("thread_02",1))
thread1.start()
#thread1.join()
thread2.start()
#thread2.join()