CODEWITHSUNDEEP
node.jsaws-lambdaserverless-framework
cinnaroll45
cinnaroll45

Reputation: 2800

Thawing Lambda functions doesn't decrease latency

I'm using serverless-warmup-plugin to run a cron that invokes a Lambda function every 10 minutes. The code for the Lambda function looks like this:

exports.lambda = (event, context, callback) => {
    if (event.source === 'serverless-plugin-warmup') {
        console.log('Thawing lambda...')
        callback(null, 'Lambda is warm!')
    } else {
        // ... logic for the lambda function
    }
}

This works on paper but in practice the cron doesn't keep the Lambda function warm even though it successfully invokes it every 10 minutes.

When the Lambda is invoked via a different event source (other than the cron) it takes around 2-3 seconds for the code to execute. Once it's executed this way, Lambda actually warms up and starts responding under 400ms. And it stays warm for a while.

What am I missing here?

Upvotes: 0

Views: 191

Answers (1)

Tom Melo
Tom Melo

Reputation: 1499

As the official documentation states:

Note

When you write your Lambda function code, do not assume that AWS Lambda always reuses the container because AWS Lambda may choose not to reuse the container. Depending on various other factors, AWS Lambda may simply create a new container instead of reusing an existing container.

It seems like a "bad architecture design" to try to keep a Lambda Container up, but, apparently it's a normal scenario your warmed container not being used when a different event source triggers a new container.

Upvotes: 1

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