我有一个非常简单的aws lambda函数，在这个函数中，我连接到一个amazon keyspaces for cassandra数据库。python中的这段代码可以工作，但我时常会遇到错误。我该如何纠正这种奇怪的行为？我假设您在初始化集群时需要进行其他设置。例如， set_max_connections_per_host . 如果有任何帮助，我将不胜感激。
错误：

('Unable to complete the operation against any hosts', {<Host: X.XXX.XX.XXX:XXXX eu-central-1>: ConnectionShutdown('Connection to X.XXX.XX.XXX:XXXX was closed')})

lambda\u函数.py：

import sessions

cassandra_db_session = None
cassandra_db_username = 'your-username'
cassandra_db_password = 'your-password'
cassandra_db_endpoints = ['your-endpoint']
cassandra_db_port = 9142

def lambda_handler(event, context):
    global cassandra_db_session
    if not cassandra_db_session:
        cassandra_db_session = sessions.create_cassandra_session(
            cassandra_db_username,
            cassandra_db_password,
            cassandra_db_endpoints,
            cassandra_db_port
        )
    result = cassandra_db_session.execute('select * from "your-keyspace"."your-table";')
    return 'ok'

会话.py：

from ssl import SSLContext
from ssl import CERT_REQUIRED
from ssl import PROTOCOL_TLSv1_2
from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider
from cassandra.policies import DCAwareRoundRobinPolicy

def create_cassandra_session(db_username, db_password, db_endpoints, db_port):
    ssl_context = SSLContext(PROTOCOL_TLSv1_2)
    ssl_context.load_verify_locations('your-path/AmazonRootCA1.pem')
    ssl_context.verify_mode = CERT_REQUIRED
    auth_provider = PlainTextAuthProvider(username=db_username, password=db_password)
    cluster = Cluster(
        db_endpoints,
        ssl_context=ssl_context,
        auth_provider=auth_provider,
        port=db_port,
        load_balancing_policy=DCAwareRoundRobinPolicy(local_dc='eu-central-1'),
        protocol_version=4,
        connect_timeout=60
    )
    session = cluster.connect()
    return session