bad-thread-instantiation / W1506

Message emitted:

threading.Thread needs the target function

Description:

The warning is emitted when a threading.Thread class is instantiated without the target function being passed as a kwarg or as a second argument. By default, the first parameter is the group param, not the target param.

Problematic code:

import threading


def thread_target(n):
    print(n**2)


thread = threading.Thread(lambda: None)  # [bad-thread-instantiation]
thread.start()

Correct code:

import threading


def thread_target(n):
    print(n**2)


thread = threading.Thread(target=thread_target, args=(10,))
thread.start()

Created by the stdlib checker.