Restarting AWS lambda function to clear cache

Question

I have a AWS Lambda function that creates an object from a s3 call in cold start. I then hold the object in the cache while the function is warm to keep load times down. W

Answer 1

In addition to some of the valid answers above: I happened to run an experiment on the (average) AWS Lambda instance lifetime. I could not find instances that ran for much longer than (on average) two hours: https://xebia.com/blog/til-that-aws-lambda-terminates-instances-preemptively/.

TL;DR: AWS Lambda is preemptively terminating instances (even those handling traffic) after two hours, with a standard deviation of 30 minutes.

Answer 2

I made an Answer based on my comment and verification from @DejanVasic

aws lambda update-function-configuration --function-name "myLambda" --description "foo"

This will force the next invokation of the lambda to "cold start".

To verify:

@timestamp, @message | sort @timestamp desc | limit 1000 | filter @message like "cold_start:true"

Answer 3

If you are using the Lambda versioning system, another way to do this is by publishing a new version and using an alias to direct all traffic to it.

Here's an example:

Publish version: aws lambda publish-version --function-name your-function-name-here

Update the alias pointing to the new version: aws lambda update-alias --function-name your-function-name-here --name alias-name-here --function-version 123 (use the function version in the output message from the first command above)

Answer 4

Use the UpdateFunctionCode API endpoint to force a refresh of all containers. AWS SDKs wrap this up to make it easier for you to call the API using your preferred language.

Answer 5

The only way force lambda to discard existing containers is to redeploy the function with something different.

Check out my answer here: Force Discard AWS Lambda Container

Good luck, Moe

Answer 6

Easiest way I found was changing something in Basic Settings like timeout:

I've upped+1 by a second, saved, and the function got refreshed