Is it possible to force Node.js/Express to process requests sequentially?

Question

I took over a project where the developers were not fully aware of how Node.js works, so they created code accessing MongoDB with Mongoose which would leave inconsistent data in the database whenever you had any concurrent request reaching the same endpoint / modifying the same data. The project uses the Express web framework.

I already instructed them to implement a fix for this (basically, to use Mongoose transaction support with automatically managed retriable transactions), but due to the size of the project they will take a lot of time to fix it.

I need to put this in production ASAP, so I thought I could try to do it if I'm able to guarantee sequential processing of the incoming requests. I'm completely aware that this is a bad thing to do, but it would be just a temporary solution (with a low count of concurrent users) until a proper fix is in place.

So is there any way to make Node.js to process incoming requests in a sequential manner? I just basically don't want code from different requests to run interleaved, or putting it another way, I don't want non-blocking operations ( .then() / await ) to yield to another task and instead block until the asynchronous operation ends, so every request is processed entirely before attending another request.

Answer 1

I have an NPM package that can do this: https://www.npmjs.com/package/async-await-queue

Create a queue limited to 1 concurrent user and enclose the code that calls Mongo in wait() / end()

Or you can also use an async mutex, there are a few NPM packages as well.