A tale of gRPC keepalives in the Lambda execution context

AWS Lambda, a serverless computing service, enables developers to focus on code execution rather than server management, offering benefits like scalability and cost-efficiency. However, it presents unique challenges, especially regarding long-lived connections and keepalive mechanisms. This blog explores AWS Lambda's execution context reuse, which can preserve global variables across invocations but does not allocate continuous compute resources, impacting tasks like setInterval. At Momento, implementing gRPC keepalive checks in AWS Lambda revealed issues with network communication due to Lambda's dormant state between invocations, leading to timeout errors and the need for reconnection. These findings prompted the decision to disable keepalive pings in Lambda, reducing client-side timeout errors but also delaying the detection of dropped connections. The experience emphasized the importance of adapting to serverless platform behaviors, such as execution context freezing and thawing, and highlighted the necessity for serverless-specific configurations and detailed monitoring to maintain service reliability.