CODEWITHSUNDEEP
pythonmultithreadinginheritancemultitasking
Milano
Milano

Reputation: 18745

Inheritance threading.Thread class does not work

I'm new in multithreading, so the answer is probably very simple.

I'm trying to make two instances of one class and run them parallel. I've read that I can use class inheritance to do that.

class hello(threading.Thread):
    def __init__(self,min,max):
        threading.Thread.__init__(self)
        time.sleep(max)

        for i in range(1000):
            print random.choice(range(min,max))

h = hello(3,5)
k = hello(0,3)

I've noticed that this does not work (the first outputs are numbers between 3 and 5)

Could you explain what am I doing wrong?
Is this inheritance dedicated to do something else?

EDIT: I want to run these two objects parallel so since the second object has smaller wait, it has to print those numbers sooner.

According to porglezomps comment, I've tried to change the code - add a method which prints those numbers but it prints it sequentially. The problem is still there.

Upvotes: 7

Views: 26667

Answers (2)

Reut Sharabani
Reut Sharabani

Reputation: 31339

Python's regular implementation of a thread already knows how to run a task, so unless you're creating a special kind of thread (not a special kind of task) - what you probably want is to use the regular thread:

def task(_min, _max): # 'min' and 'max' are actual functions!
    time.sleep(_max)
    for _ in range(1000):
        print random.choice(range(_min,_max))

And now create a thread to run the task:

t1 = threading.Thread(target=task, args=(3, 5,))
t2 = threading.Thread(target=task, args=(3, 5,))

t1.start()
t2.start()

Upvotes: 2

porglezomp
porglezomp

Reputation: 1348

The documentation for threading says that you should override the run() method, and then use the start() method to begin execution on a new thread. In your case, your code should be:

class Hello(threading.Thread):
    def __init__(self, min, max):
        self.min, self.max = min, max
        threading.Thread.__init__(self)

    def run(self):
        time.sleep(self.max)

        for i in range(1000):
            print random.choice(range(self.min, self.max))

# This creates the thread objects, but they don't do anything yet
h = Hello(3,5)
k = Hello(0,3)

# This causes each thread to do its work
h.start()
k.start()

Upvotes: 25

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