Resources that can be reused across multiple invocations of the Lambda function should be initialized at module level, outside the handler
function. When the same Lambda container is reused for multiple function invocations, existing instances including SDK clients and database
connections can be reused without recreating them. It is a good practice to initialize AWS clients, like boto3, and database connections outside the
handler function to avoid recreating them on every Lambda invocation. Failing to do so can lead to performance degradation, increased latency, and
even higher AWS costs.
What is the potential impact?
Performance degradation is the primary concern, as recreating resources adds significant latency to each Lambda invocation. This can result in
slower response times and higher costs due to increased execution duration.
Availability risks may also emerge under high load scenarios, as the additional overhead from resource recreation can cause functions to timeout
more frequently or hit concurrency limits sooner than necessary.
Increased API throttling is another potential issue, as recreating resources may lead to more frequent authentication requests and connection
establishments, potentially triggering rate limits.
Exceptions
If the resource contains sensitive information that should not be shared across invocations, it may be necessary to initialize it within the
handler function. However, this should be done cautiously and only when absolutely necessary.
