Feature request: sequential async processing

[revmischa]

Use case

Sometimes I have records that I want processed one at a time, but my processor function happens to be async.

Solution/User Experience

It would be nice to request sequential processing of records with async handlers.

Alternative solutions

No response

Acknowledgment

• This feature request meets Powertools for AWS Lambda (TypeScript) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and .NET

Future readers

Please react with 👍 and your use case to help us understand customer demand.

[dreamorosi]

Hi @revmischa thank you for taking the time to open this issue.

As we discussed in Discord, I think the request is valid and I remember hearing it from other customers in the past few weeks.

I'm adding this to the backlog so that it can be picked up.

If anyone is interested in contributing, please leave a comment so we dan discuss an implementation.

[revmischa]

I also have a use case where I have an async handler but need to process FIFO events sequentially.

I think it's a safe assumption that most every handler anyone will ever write will be async. How else will do you I/O otherwise? And what is the use of a handler that can't do I/O?

[dreamorosi]

That's very fair, we are focused on releasing v2 this & next week.

After that we'll be able to reprise working on new features for the existing utilities. This is one of the issues I'd like to pick up relatively soon.

[arnabrahman]

I can work on this next. I can see there is a section in the doc about Async processing,

*If your function is async returning a Promise, use BatchProcessor and processPartialResponse * 
 If your function is not async, use BatchProcessorSync and processPartialResponseSync

So, based on the PR description, do we now want to have the option to use BatchProcessorSync and processPartialResponseSync in an async function? It would be helpful if I could have some more context. @dreamorosi, whenever you are free.

[revmischa]

Also just curious, what is the use case for sync processing? You can't really do I/O without async right? So what use is a SQS processing function that can't do any I/O?