Question

Trying to learn multi-threading. I downloaded some sample code to play with, and I ended up with this:

import threading
import time

class myThread (threading.Thread):
    def __init__(self, threadID, name, delay, counter):
        super().__init__()
        self.threadID = threadID
        self.name = name
        self.delay = delay
        self.counter = counter
        threading.Thread.__init__(self)
        print(name,"created")
        print(self.name,"created")
    def run(self):
        print ("Starting " + self.name)
        print_time(self.name, self.delay, self.counter)
        print ("Exiting " + self.name)

def print_time(threadName, delay, counter):
    while counter:
        time.sleep(delay)
        print (threadName, time.ctime(time.time()))
        counter -= 1

# Create new threads
thread1 = myThread(1, "a", 1, 5)
thread2 = myThread(2, "b", 2, 3)

# Start new Threads
thread1.start()
thread2.start()
thread1.join()
thread2.join()

print ("Exiting Main Thread")

But my output was unexpected, to say the least.

a created
Thread-2 created
b created
Thread-4 created
Starting Thread-2
Starting Thread-4
Thread-2 Mon Jan 14 16:14:29 2013
Thread-2 Mon Jan 14 16:14:30 2013
Thread-4 Mon Jan 14 16:14:30 2013
Thread-2 Mon Jan 14 16:14:31 2013
Thread-2 Mon Jan 14 16:14:32 2013
Thread-4 Mon Jan 14 16:14:32 2013
Thread-2 Mon Jan 14 16:14:33 2013
Exiting Thread-2
Thread-4 Mon Jan 14 16:14:34 2013
Exiting Thread-4
Exiting Main Thread

Why doesn’t self.name evaluate to “a” or “b” after assigning it that way?

Answer 1

name gets reinitialized in threading.Thread.__init__(self). There is no reason to call parent constructor twice.