We are converting AWS Lambdas from Java due to excessive cold start times. Usage: These lambdas handle XML and JSON payloads, they use s3, API Gateway, RDS, DynamoDB, and external API's. Most of our developers are only experienced in java. These three languages (Go, Node.js, and Python) were discussed, but no consensus has been reached yet.
I was initially going to suggest JavaScript due to the smaller size needs of AWS Lambdas code and the larger range of libraries and community available (and to avoid Python for this). But I have to agree with the recommendations and rationale of @ayildirim above and I think you should choose any reasonable language that is low-overhead, fast startup, and best supported by AWS Lambda, and that is probably Go. I don't think you are likely to go wrong with that, while you can potentially with the others.
So I'd agree, on the strength of AWS Lambda support and the solid performance of Go, it seems like your best choice here for Lambdas (and I'm going to need to consider that myself going forward... pardon the pun).
I've worked with all three of these languages and also with Java developers converting to these languages and far and away Go is the easier one to convert to. With the improved cold-start times and the ease of conversion for a Java developer, it is a no-brainer for me.
The hardest part of the conversion though is going to be the lack of traditional Classes so you have to be mindful of that, but Go Structs and interfaces tend to make up for what is lost there.
Full Disclosure: I'm a 95% Go convert (from Python) at this point in time.
