Passing parameter to function while multithreading

Question

I'm learning about multithreading and when I try to pass a parameter to my function in each thread it will process sequentially. Why is that?

import time
import threading

start = time.perf_counter()

def sleepy_duck(name):
    print(name, "duck going to sleep 1 sec")
    time.sleep(1)
    print(name, "waking up")    


t1 = threading.Thread(target=sleepy_duck("Johny"))
t2 = threading.Thread(target=sleepy_duck("Dicky"))
t3 = threading.Thread(target=sleepy_duck("Loly"))

t1.start()
t2.start()
t3.start()

t1.join()
t2.join()
t3.join()

finish = time.perf_counter()
print("The ducks slept ", finish-start, " seconds.")

Result:

Johny duck going to sleep 1 sec
Johny waking up
Dicky duck going to sleep 1 sec
Dicky waking up
Loly duck going to sleep 1 sec
Loly waking up
The ducks slept  3.0227753  seconds.

jackal · Accepted Answer · 2022-08-05 14:38:39Z

1

Try this and note the difference:

import time
import threading

start = time.perf_counter()

def sleepy_duck(name):
    print(name, "duck going to sleep 1 sec")
    time.sleep(1)
    print(name, "waking up")    


t1 = threading.Thread(target=sleepy_duck, args=("Johnny",))
t2 = threading.Thread(target=sleepy_duck, args=("Dicky",))
t3 = threading.Thread(target=sleepy_duck, args=("Loly",))

t1.start()
t2.start()
t3.start()

t1.join()
t2.join()
t3.join()

finish = time.perf_counter()
print("The ducks slept ", finish-start, " seconds.")

The way you did it originally the target was None

answered Aug 5, 2022 at 14:38

jackal

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Comments

Keegan Cowle · Accepted Answer · 2022-08-05 14:38:58Z

1

You're not actually multithreading. You're invoking the sleepy_duck method when setting up your threads.

the correct way is to:

t1 = threading.Thread(target=sleepy_duck, args=("Johny",))
t2 = threading.Thread(target=sleepy_duck, args=("Dicky",))
t3 = threading.Thread(target=sleepy_duck, args=("Loly",))

answered Aug 5, 2022 at 14:38

Keegan Cowle

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