python中start和run方法的区别

threading.Thread.__init__(self,target=thread_run())

def __init__(self, group=None, target=None, name=None,
                 args=(), kwargs=None, *, daemon=None):
        assert group is None, "group argument must be None for now"
        if kwargs is None:
            kwargs = {}
        self._target = target
        self._name = str(name or _newname())
        self._args = args
        self._kwargs = kwargs

thread1.start()
    def start(self):
        if not self._initialized:
            raise RuntimeError("thread.__init__() not called")
        if self._started.is_set():
            raise RuntimeError("threads can only be started once")
        with _active_limbo_lock:
            _limbo[self] = self
        try:
            _start_new_thread(self._bootstrap, ())
        except Exception:
            with _active_limbo_lock:
                del _limbo[self]
            raise
        self._started.wait()

_start_new_thread = _thread.start_new_thread
def start_new_thread(function: Callable[..., Any], args: tuple[Any, ...], kwargs: dict[str, Any] = ...) -> int: ...

def _bootstrap_inner(self):
    try:
        self._set_ident()
        self._set_tstate_lock()
        if _HAVE_THREAD_NATIVE_ID:
            self._set_native_id()
        self._started.set()
        with _active_limbo_lock:
            _active[self._ident] = self
            del _limbo[self]

        if _trace_hook:
            _sys.settrace(_trace_hook)
        if _profile_hook:
            _sys.setprofile(_profile_hook)
        try:
            self.run()

 def run(self):
        try:
            if self._target:
                self._target(*self._args, **self._kwargs)
        finally:
            # Avoid a refcycle if the thread is running a function with
            # an argument that has a member that points to the thread.
            del self._target, self._args, self._kwargs

def thread_run():
    print ("overwrite: 开始线程:" + threading.current_thread().name)
    time.sleep(2)
    print ("overwrite: 退出线程:" + threading.current_thread().name)

class myThread (threading.Thread):
    def __init__(self, threadID, name, delay):
        threading.Thread.__init__(self,target=thread_run())
        self.threadID = threadID
        self.name = name
        self.delay = delay
        thread1.start()

thread1.join()
print ("退出主线程")