# Source code for folder_extract_mt

    import os
    import multiprocessing
    from multiprocessing import Queue
    import time

    # Function to list files in a directory

    def list_files(directory, queue):
        """
        Walks through the directory and its subdirectories to list all files.
        Adds each file path to the queue after encoding to handle invalid surrogate characters.

        Args:
            directory (str): The root directory to start listing files from.
            queue (Queue): The queue to put the file paths into.
        """
        try:
            for root, dirs, files in os.walk(directory):
                for file in files:
                    file_path = os.path.join(root, file)
                    # Filter out invalid surrogate characters
                    file_path = file_path.encode('utf-8', 'surrogateescape').decode('utf-8', 'replace')
                    queue.put(file_path)
        except PermissionError as e:
            print(f"PermissionError: {e}")
        except Exception as e:
            print(f"Error: {e}")

    # Function to write files to the output file

    def write_files(queue, output_file):
        """
        Writes file paths from the queue to the output file.
        Stops writing when a None value is encountered in the queue.

        Args:
            queue (Queue): The queue to get the file paths from.
            output_file (str): The file to write the file paths to.
        """
        with open(output_file, 'w', encoding='utf-8') as f:
            while True:
                file_path = queue.get()
                if file_path is None:
                    break
                f.write(file_path + '\n')

    # Main function

    def main(root_directory, output_file, num_processes):
        """
        Coordinates the listing and writing of files using multiple processes.

        Args:
            root_directory (str): The root directory to start listing files from.
            output_file (str): The file to write the file paths to.
            num_processes (int): The number of processes to use for listing files.
        """
        queue = Queue()
        directories = [os.path.join(root_directory, d) for d in os.listdir(root_directory) if os.path.isdir(os.path.join(root_directory, d))]

        # Start the writer process
        writer_process = multiprocessing.Process(target=write_files, args=(queue, output_file))
        writer_process.start()

        # Start the worker processes
        processes = []
        for directory in directories:
            process = multiprocessing.Process(target=list_files, args=(directory, queue))
            process.start()
            processes.append(process)

        # Wait for all worker processes to finish
        for process in processes:
            process.join()

        # Signal the writer process to exit
        queue.put(None)
        writer_process.join()

    if __name__ == "__main__":
        root_directory = '/home/cni/'
        output_file = '/home/filenames_py.txt'
        num_processes = 10  # Adjust the number of processes as needed

        start_time = time.time()
        main(root_directory, output_file, num_processes)
        end_time = time.time()

        print(f"Runtime: {end_time - start_time:.2f} seconds")