新手写了一个多线程的爬虫，所有线程都执行完了，但是一直占着 1.5GB 的内存（任务数越多不释放的内存越多） 不知道怎么排查哪里出问题，pympler 看不太懂问题到底出在哪里，请教该如何正确的排查问题

执行多线程函数的代码：

    def mainfunc(tasknum, thread):
        tr = tracker.SummaryTracker()
        tr.print_diff()
        list = []
        for i in range(tasknum):
            list.append(str(i))
        pool = threadpool.ThreadPool(thread)
        requests = threadpool.makeRequests(childfunc, list)
        for req in requests:
            pool.putRequest(req)
        pool.wait()
        tr.print_diff()

tr.print_diff()打印的内容

初始化：

                     types |   # objects |   total size
========================== | =========== | ============
                      list |        3741 |    350.84 KB
                       str |        3739 |    260.01 KB
                       int |         673 |     18.40 KB
                      dict |           2 |    352     B
                     tuple |           4 |    256     B
                      code |           1 |    144     B
     function (store_info) |           1 |    136     B
                      cell |           2 |     96     B
  functools._lru_list_elem |           1 |     80     B
                    method |          -1 |    -64     B

所有线程结束后：

                                types |   # objects |   total size
===================================== | =========== | ============
                                 dict |      202860 |     43.69 MB
                                 list |      100169 |      8.47 MB
                                  str |      102446 |      5.62 MB
               threadpool.WorkRequest |      100000 |      5.34 MB
                                  int |      100836 |      3.08 MB
                   _io.BufferedReader |         294 |      2.35 MB
                                tuple |        1480 |     93.30 KB
                                 type |          76 |     85.98 KB
                                 code |         572 |     80.57 KB
                                bytes |        1219 |     51.49 KB
                                  set |          32 |     43.50 KB
                        socket.socket |         294 |     27.56 KB
       pymysql.connections.Connection |         294 |     16.08 KB
                      socket.SocketIO |         294 |     16.08 KB
  DBUtils.SteadyDB.SteadyDBConnection |         294 |     16.08 KB

附上可以复现问题的最小化代码，执行完输出done后，htop显示python3一直占用着那一部分内存，除非kill掉否则不释放（发不了链接base64编码了一下）

#!/usr/bin/pyyhon
# -*- coding: UTF-8 -*-
import threadpool, time, requests, base64

s = requests.Session()

def childfunc(id):
    url = base64.b64decode('aHR0cHM6Ly91cGxvYWQud2lraW1lZGlhLm9yZy93aWtpcGVkaWEvY29tbW9ucy9mL2ZmL1BpemlnYW5pXzEzNjdfQ2hhcnRfMTBNQi5qcGc=')
    res = s.get(url, timeout=(5, 60))

def mainfunc(tasknum, thread):
    list = []
    for i in range(tasknum):
        list.append(str(i))
    pool = threadpool.ThreadPool(thread)
    requests = threadpool.makeRequests(childfunc, list)
    for req in requests:
        pool.putRequest(req)
    pool.wait()
    print('done')
    while True:
        time.sleep(1)

if __name__ == '__main__':
    mainfunc(10000, 50)