CODEWITHSUNDEEP
pythonmultithreading
Freddy Mcloughlan
Freddy Mcloughlan

Reputation: 4506

I can't run two threads at once with arguments

I can't execute the second thread after starting the first.

This is my attempt at running two threads:

def test1(foo):
    print(foo)


def test2(bar):
    while True:
        time.sleep(3)
        print(bar)


threading.Thread(target=test2('Test2')).start()
threading.Thread(target=test1('Test1')).start()

The first thread loops forever (as intended), but threading.Thread(target=test1('Test1')).start() is never executed.

Output:

Test2
Test2
Test2
...

Expected output

Test1
Test2
Test2
Test2
...

Edit: Simplified the entire question body with new functions

Upvotes: 0

Views: 127

Answers (2)

mhawke
mhawke

Reputation: 87084

To fix, use the args argument for Thread:

threading.Thread(target=dummyAction, args=('Working',)).start()
threading.Thread(target=play, args=(pathToFile,)).start()

In your first example this is incorrect:

threading.Thread(target = play(pathToFile)).start()

because it actually calls function play(pathToFile) and sets its return value to target before creating and starting the thread. So it was merely coincidence that it seemed to work. In fact the dummyAction() function would execute in a new thread, but the play() function was actually executing in the main thread.

And that explains why your second example did not to start the second thread; the program is blocked running dummyAction().

Upvotes: 3

shauli
shauli

Reputation: 412

This is how you're supposed to pass the arguments to the threads:

threading.Thread(target=dummyAction, args=('Working',)).start()
threading.Thread(target=play, args=(pathToFile,)).start()

Upvotes: 1

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