terminal outputs appear after KeyboardInterrupt

edit

Hello, I am trying to complete a basic task. I starting a node with parameter file via launch file. When I run the node without launch file, it works fine and output can be seen on terminal. However when I run it via launch file, no output appears until I stop it with Ctrl + C.

My node:

#/usr/bin/env python3
import rclpy


def main():
    rclpy.init()
    hello_world = rclpy.create_node("hello_world")
    hello_world.declare_parameter("freq", 1.0)
    hello_world.declare_parameter("text", "Hello Param")
    counter = 1
    while rclpy.ok():
        try:
            rclpy.spin_once(
                hello_world, timeout_sec=hello_world.get_parameter("freq").value)
        except KeyboardInterrupt:
            break
        print(hello_world.get_parameter("text").value)
        print(f"{counter}\n")
        counter += 1

    hello_world.destroy_node()
    rclpy.shutdown()


if __name__ == "__main__":
    main()

the launch file

#!/usr/bin/env python3

import os
from ament_index_python import get_package_share_directory

from launch import LaunchDescription
from launch_ros.actions import Node


def generate_launch_description():
    dir_hello_world = get_package_share_directory("hello_world")
    return LaunchDescription([
        Node(
            package="hello_world",
            node_executable="hello_world",
            node_name="text_counter",
            parameters=[os.path.join(dir_hello_world, "hello_world.yaml")],
            output="screen"
        )
    ])