Latest Concurrency Articles

AWS Lambda concurrency is one of the most important concepts to understand before running serverless applications in production. Lambda can scale quickly, but that does not mean every downstream system can handle unlimited parallel requests.

AWS Lambda already provides horizontal concurrency by running more execution environments as request volume grows. But a single invocation can still spend most of its lifetime waiting for HTTP APIs, S3, DynamoDB, Redis, databases, or other network services.

Modern applications rarely do only one thing at a time. They call APIs, query databases, read files, send notifications, process messages, and wait for external services. If every operation runs one after another, the application often spends most of its time waiting instead of doing useful work.