What is cold start, and how can you mitigate it?
A cold start occurs when AWS Lambda initializes a new execution environment in response to an invocation, which adds latency before the function begins execution. This typically happens when a function is invoked after a period of inactivity or when scaling to handle concurrent requests. Cold starts are more noticeable in VPC-connected functions and interpreted languages like Python and Node.js.
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First-time invocation after deployment or inactivity
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Scaling to new concurrent executions beyond warm environments
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Using VPCs without properly configured networking
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Large dependencies that slow down initialization
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Use provisioned concurrency to keep instances warm
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Minimize the size of your deployment package
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Avoid unnecessary VPC usage or use efficient VPC configurations
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Use lighter runtimes like Go or Node.js for faster start-up
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Keep initialization code outside the handler function