为什么python使用线程池会丢失部分数据？

import os
from concurrent.futures import ThreadPoolExecutor
from time import perf_counter
import time
import threading as th
lock=th.Lock()
def write(text,path='re.txt'):
    lock.acquire()
    with open(path,'a') as fp:
        fp.write(text)
    lock.release()
def make_test_txt(path='test_txt.txt'):
    with open(path,'w') as fp:
        for i in range(100):
            fp.write(str(i)+'\n')
#os.remove('re.txt')
make_test_txt()
with open('test_txt.txt') as fp:
    texts=fp.readlines()
print(len(texts))
t=perf_counter()
pool=ThreadPoolExecutor(max_workers=2)
pool.map(write,texts)
pool.shutdown(wait=True)
time.sleep(1)
with open('re.txt') as fp:
    texts2=fp.readlines()
print(len(texts2))