Python 读取大文件 chunk(block_size) 的疑惑

生成一个 10 行的文本文件，每一行以 "\n" 结尾，统计行数为 10 。

def generate_file():
    with open("line.log", "w") as f:
        for i in range(1, 10+1):
            f.write(f"Line is: your target line{i} to print\n")

def chunked_file_reader(fp, block_size=4 * 1024):
    while True:
        chunk = fp.read(block_size)
        if not chunk:
            break
        yield chunk

def get_line_count(fname):
    count = 0
    with open(fname) as fp:
        for chunk in chunked_file_reader(fp):
            count += chunk.count("\n")
    return count


generate_file()
line_count = get_line_count("line.log"）
# > 10

block_size 亦或者说 buffering 传入的大小是每一行的长度，count 结果会变成 9 ，求解

def return_count(fname):
    count = 0
    with open(fname) as fp:
        line = fp.readline()
        for chunk in chunked_file_reader(fp, len(line)):
            count += chunk.count("\n")
    return count


generate_file()
line_count = get_line_count("line.log"）
# > 9