What is Cold Start?
Turkish: Soğuk Başlangıç (Cold Start)
A cold start is the extra latency when a serverless function or scaled instance initializes before handling its first request.
What is Cold Start?
A cold start is the startup cost paid when a function, container, or runtime is not already warm when the first request arrives. Loading code, starting the runtime, preparing dependencies, and sometimes opening database connections all add to the delay.
Cold starts are most visible in serverless architectures. If a Lambda function has not been invoked for a while, the platform may shut down its execution environment. The next request has to create it again. A similar delay can appear when an auto-scaling container platform starts a new instance.
Causes and Mitigation
Large bundles, heavy framework initialization, unnecessary global startup code, slow network dependencies, and first-request configuration or secret reads can all increase cold start time. Runtime choice also matters; Node.js, Python, Java, and .NET do not initialize in the same way.
Mitigation options include smaller bundles, lazy loading, careful connection pool initialization, provisioned concurrency for critical paths, lighter runtimes, and edge execution environments. Keeping every function warm can be expensive, so the decision should be based on real traffic patterns and user-visible latency. For serverless function design, p95 and p99 latency are usually more useful than averages.
Related Terms
A Lambda function is a serverless code unit that runs when triggered, with automatic scaling and pay-per-use billing.
Serverless FunctionA serverless function is a short-lived cloud code unit triggered by events such as HTTP requests, queue messages, cron jobs, or file uploads.
ServerlessServerless is a cloud architecture model where server provisioning and capacity planning move to the provider while code runs in response to events.