A producer sends messages to an Amazon SQS Standard Queue. The Event Source Mapping (ESM) is configured with Provisioned Mode, which pre-allocates dedicated event pollers between a configurable minimum and maximum. Each poller handles up to 1 MB/s throughput, 10 concurrent Lambda invocations, and 10 SQS API calls per second.

The Lambda function runs on Lambda Managed Instances (LMI) — an EC2-backed execution model that supports multiconcurrency, allowing each execution environment to handle multiple SQS batches simultaneously. LMI instances run inside a private VPC with outbound access via a NAT Gateway.

Partial batch failure reporting (ReportBatchItemFailures) ensures only failed messages are returned to the queue. After 3 failed attempts, messages are moved to a Dead Letter Queue. A CloudWatch Alarm fires as soon as any message lands in the DLQ.

This pattern deploys one SQS Standard Queue, one Dead Letter Queue, one Lambda function with an LMI Capacity Provider, one Event Source Mapping with Provisioned Mode, a VPC with private subnets and NAT Gateway, and one CloudWatch Alarm.