python使用PooledDB 执行报错连接数不够？

Question

import pymysql.cursors
from dbutils.pooled_db import PooledDB

host = '127.0.0.1'
port = 3306
user = 'root'
password = 'root'
database = 'report'
class MySQLConnectionPool:
    def __init__(self, ):
        self.pool = PooledDB(
            creator=pymysql,  # 使用链接数据库的模块
            mincached=10,  # 初始化时，链接池中至少创建的链接，0表示不创建
            maxconnections=200,  # 连接池允许的最大连接数，0和None表示不限制连接数
            blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
            host=host,
            port=port,
            user=user,
            password=password,
            database=database
        )

    def open(self):
            self.conn = self.pool.connection()
            self.cursor = self.conn.cursor(cursor=pymysql.cursors.DictCursor)  # 表示读取的数据为字典类型
            return self.conn, self.cursor
    def close(self, cursor, conn):
        cursor.close()
        conn.close()

    def select_one(self, sql, *args):
            """查询单条数据"""
            conn, cursor = self.open()
            cursor.execute(sql, args)
            result = cursor.fetchone()
            self.close(conn, cursor)
            return result

    def update_one(self, sql, args):
        """更新数据"""
        self.execute(sql, args, isNeed=True)

    def insert_all(self, sql, datas):
            """插入多条批量插入"""
            conn, cursor = self.open()
            try:
                cursor.executemany(sql, datas)
                conn.commit()
                return {'result': True, 'id': int(cursor.lastrowid)}
            except Exception as err:
                conn.rollback()
                print(err)
                return {'result': False, 'err': err}
    def insert(self,sql,data):
        self.execute(sql, data, isNeed=True)

    def execute(self, sql, args, isNeed=False):
        """
        执行
        :param isNeed 是否需要回滚
        """
        conn, cursor = self.open()
        if isNeed:
            try:
                cursor.execute(sql, args)
                conn.commit()
            except:
                conn.rollback()
        else:
            cursor.execute(sql, args)
            conn.commit()
        self.close(conn, cursor)

import datetime
import sched
import time

import pyodbc

from sqlConfig import MySQLConnectionPool


def time_printer():
    now = datetime.datetime.now()
    print(now)
    # 连接数据库
    conn = pyodbc.connect(r'Driver={Microsoft Access Driver (*.mdb, *.accdb)};DBQ=D:\东和.accdb')

    # 创建连接池对象
    ConnPool = MySQLConnectionPool()

    # 创建游标
    cursor = conn.cursor()

    # 查询数据
    cursor.execute('SELECT * FROM 配方列表')

    # 清空
    sql_update_one = "delete from plan_peifang_list where 1=%s"
    ConnPool.update_one(sql_update_one, (1,))
    list1 = []
    # 逐行读取数据
    for row in cursor.fetchall():
        print(row[0])
        sql1 = "INSERT INTO plan_peifang_list (dingdanhao, kehu, zhilianghao, zhongliang, time, waibuzhilianghao) VALUES (%s, %s, %s, %s, %s, %s)"
        ConnPool.insert(sql1, (row[0], row[1], row[2], row[3], row[4], row[5]))
        list1.append(row)
    loop_monitor()

def loop_monitor():
    s = sched.scheduler(time.time,time.sleep)
    s.enter(5,1,time_printer,())
    s.run()

if __name__  == "__main__":
    loop_monitor()

这个定时任务执行一段时间后报错：Traceback (most recent call last):
File "D:\pythonProject.venv\Lib\site-packages\dbutils\pooled_db.py", line 336, in connection

con = self._idle_cache.pop(0)
      ^^^^^^^^^^^^^^^^^^^^^^^

IndexError: pop from empty list

During handling of the above exception, another exception occurred:

Traceback (most recent call last): 请问是哪里写的不对？连接数用了没关吗？