在AWS SNS中，当两个Lambda订阅同一个主题时，可能会导致重复消息的发送。解决此问题的方法是使用SNS提供的过滤器功能，对订阅进行过滤，确保每个Lambda只收到它所需的消息。

示例代码：

1. 创建SNS主题并发布消息：

import boto3

sns = boto3.client('sns')

response = sns.create_topic(Name='test-topic')

topic_arn = response['TopicArn']

response = sns.publish( TopicArn= topic_arn, Message='Hello World!' )

2. 创建两个Lambda函数作为订阅者，并定义过滤规则：

import boto3

lambda_client = boto3.client('lambda') sns_client = boto3.client('sns')

def create_subscription(filter_policy):

lambda_name = 'lambda-test'
topic_arn = sns_client.create_topic(Name='test-topic')['TopicArn']
lambda_arn = lambda_client.get_function(FunctionName=lambda_name)['Configuration']['FunctionArn']

# Create Lambda subscription with filter policy 
subscription = sns_client.subscribe(
    TopicArn= topic_arn,
    Protocol='lambda',
    Endpoint= lambda_arn,
    Attributes={
        'FilterPolicy': filter_policy
    }
)
print('Subscription created with filter policy:', filter_policy)
return subscription['SubscriptionArn']

Subscribe Lambda-1 with a filter policy

lambda_1_filter_policy = {'test-path': ['foo']} lambda_1_subscription_arn = create_subscription(lambda_1_filter_policy)

Subscribe Lambda-2 with a different filter policy

lambda_2_filter_policy = {'test-path': ['bar']} lambda_2_subscription_arn = create_subscription(lambda_2_filter_policy)

3. 在Lambda-1中处理消息：

import json

def lambda_handler(event, context): print('Lambda-1:', event) message = json.loads(event['Records'][0]['Sns']['Message'])

# Process only messages that match the filter policy
if message.get('test-path') == ['foo']:
    print('Processing message:', message)
else:
    print('Ignoring message:', message)

4. 在Lambda