Trouble with serial communication between Arduino and python

[n00b_1]

Hello,
I am using an Arduino Uno connected to my computer. I have programmed it to send a "hello world" message every second. On my laptop, I have a program using pyserial that should read the serial and print it. With my current code, nothing prints until I disconnect the Arduino. Then, it prints a long string with all of the "hello world"s. Can you please help me change this so it becomes Realtime?
Thanks

Arduino Code

  Serial.begin(9600);
}

void loop() {
  Serial.println("Hello World");
  delay(1000);
}

Python Code:

import serial
import time

# Initialize serial connection
arduino = serial.Serial('COM3', 9600)  # Replace 'COM3' with the appropriate serial port
time.sleep(2)  # Wait for 2 seconds to ensure the connection is established

while True:
    if arduino.in_waiting > 0:
        # Read the incoming data
        data = arduino.readline().decode().strip()
        print(data)

[jremington]

How is the Python code supposed to recognize that "Hello World" is one message?

The Arduino Serial.println() command is sending line terminators (often <CR> and <LF>, or ASCII characters standing for carriage return and line feed), so you need to learn how to write Python code that recognizes those line terminators, in order to separate individual messages.

[horace]

try the following Python to receive the serial data

import serial
import time

serialPort = serial.Serial(
    port="COM3", baudrate=9600, bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE
)
serialString = ""  # Used to hold data coming over UART
while 1:
    # Wait until there is data waiting in the serial buffer
    if serialPort.in_waiting > 0:

        # Read data out of the buffer until a carraige return / new line is found
        serialString = serialPort.readline()

        # Print the contents of the serial data
        try:
            print(serialString.decode("Ascii"))
        except:
            pass

also have a look at two-ways-communication-between-python3-and-arduino