Python Not able to echo ROS2 topics published on thread

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I have a node with two topics i am publishing i created two threads and publishing them every 10 ms however when i list topics i could see the topics but when i subscribe or echo i don't get anything

import rclpy
from rclpy.node import Node
import threading
from std_msgs.msg import String
from sensor_msgs.msg import Image
from collections import deque
from rclpy.node import Node

rclpy.init()
g_node = rclpy.create_node('node_name') 
rgb_image_queue = deque()
depth_image_deque = deque()

g_queue_size = 1
topic_name = "/test_topic"
topic_name2 = "/test_topic"

def rgb_img_publisher_thread() -> None:
   publisher_ = g_node.create_publisher(String, topic_name, g_queue_size)
   i = 0
   while True:
       rclpy.spin_once(g_node) 
       # image_raw_ = depth_image_deque.pop()
       msg = String()
       msg.data = 'Test Img Publisher: %d' % i
       i += 1                                                       
       publisher_.publish(msg)  

def depth_img_publisher_thread() -> None:                                                         
   publisher_ = g_node.create_publisher(String, topic_name2, g_queue_size)
   i = 0
   while True:
       rclpy.spin_once(g_node)                                                                                    
       # image_raw_ = rgb_image_queue.pop()
       msg = String()
       msg.data = 'Test Img Publisher: %d' % i
       i += 1                                                       
       publisher_.publish(msg)                                                            


def main(args=None):

   while rclpy.ok(): 
       print("here ")
       rclpy.spin_once(g_node) 
       thread2 = threading.Thread(target=rgb_img_publisher_thread())
       thread1 = threading.Thread(target=depth_img_publisher_thread())

       thread2.start()
       thread1.start()
       thread2.join()
       thread1.join()


rclpy.shutdown()


if __name__ == '__main__':
    main()

The following code works but the threads are not concurrent. they are executing serially not concurrent.

def main1(args=None):
    i = 0
    while rclpy.ok():
        publisher1 = g_node.create_publisher(String, '/topic1', g_queue_size)
        publisher2 = g_node.create_publisher(String, '/topic2', g_queue_size)
        msg = String()
        i += 1
        msg.data = 'Test Img Publisher: %d' % i
        thread2 = threading.Thread(publisher2.publish(msg))
        thread1 = threading.Thread(publisher1.publish(msg))
        thread2.start()
        thread1.start()
        thread2.join()
        thread1.join()

if __name__ == '__main__':
    main1()