import multiprocessing as mp

def read_lines_in_range(file_path, start_line, end_line, keyword):
    """
    Reads lines from a file within a specified range without loading the entire file into memory.
    Stops when the keyword is found.

    :param file_path: Path to the text file.
    :param start_line: Starting line number (inclusive).
    :param end_line: Ending line number (inclusive).
    :param keyword: The keyword to search for in the file.
    :return: The line containing the keyword or None if not found.
    """
    try:
        with open(file_path, 'r', encoding='utf-8') as file:
            # Seek to the start line
            for current_line in range(1, start_line):
                next(file)

            # Read lines within the specified range
            for current_line in range(start_line, end_line + 1):
                try:
                    line = next(file).strip()
                except StopIteration:
                    break
                if keyword.lower() in line.lower():
                    return line
    except FileNotFoundError:
        print(f"Error: The file '{file_path}' was not found.")
    except UnicodeDecodeError:
        print("Error: The file encoding is not UTF-8.")
    except Exception as e:
        print(f"An error occurred: {e}")
    return None

def process_chunk(file_path, start_line, chunk_size, keyword):
    """
    Process a chunk of lines to search for the keyword.
    Stops when the keyword is found in the chunk.

    :param file_path: Path to the text file.
    :param start_line: Starting line number of the chunk.
    :param chunk_size: Number of lines in the chunk.
    :param keyword: The keyword to search for in the file.
    :return: The line containing the keyword or None if not found.
    """
    end_line = start_line + chunk_size - 1
    return read_lines_in_range(file_path, start_line, end_line, keyword)

if __name__ == "__main__":
    file_path = 'text.txt'
    start_line = 0
    end_line = 40000000
    chunk_size = 10000  # Keep chunk size for balancing
    keyword = 'something@gmail.com'

    chunks = [(file_path, i, chunk_size, keyword) for i in range(start_line, end_line, chunk_size)]

    with mp.Pool(mp.cpu_count()) as pool:
        results = pool.starmap(process_chunk, chunks)

    hits = [result for result in results if result is not None]
    total_hits = len(hits)

    print(f'Total hits in document: {total_hits}')

    # Print lines where the keyword was found
    for line in hits:
        print(line)