Approaches to bundling

[FredrikAugust]

Hey! We're avid users of awilix, and have a great time using it. However, we're starting to run into performance issues during startup due to a lot of dependencies (not Awilix' fault), and the logical next step is to implement bundling. This, however, is not compatible with loadModules using a glob, from what I've understood. So I wanted to hear if/how people have solved this challenge. Moving to manually registering everything seems like the most straight-forward, but can be tedious. I know vite for instance has import.meta.glob which you can use, but we use rslib so we don't have that luxury. Furthermore, we also use dynamic strings to determine the globs which is incompatible with import.meta.glob.

[jeffijoe]

Have you profiled your startup performance and identified whether it's actually imports that are degrading performance? I've never understood the desire to bundle server code. If anything, I would have thought that using ESM import would help the runtime parallelize the load and parse steps for each file, whereas a single bundle would force it to parse the entire code sequentially.

[FredrikAugust]

Yep. I'm not a master of reading the flamegraphs from 0x, but if I'm not mistaken, in our case, when starting up the application and exiting before starting any application code, ~13-19% of the root stack here is imports and other v8/init calls.

Our goal is to improve startup times. I'm sorry if I wasn't entire clear in the "issue" — the runtime performance is great, it's just the time to start we're struggling with.

Regarding why we want to do this; from my understanding, the non-bundled solution causes node to have to traverse the entire dependency graph, load from files and generally perform a lot of IO operations to get everything "set up". My thought is that by bundling the code base and ideally dependencies it will reduce the amount of files that need to be read as it will have more of them in memory.

https://aws.amazon.com/blogs/compute/optimizing-node-js-dependencies-in-aws-lambda/

I haven't ran any benchmarks to support this claim as I couldn't get our application to start bundled due to the problems outlined in the post.

EDIT: I misread the original flamegraph. Updated the values.

[jeffijoe]

Gotcha. I’d recommend manually registering dependencies then.

[FredrikAugust]

Here is what I believe is a more correct screenshot of the flamegraph. Thanks for your quick response! :)

[FredrikAugust]

I should also note that part of the reason we're investigating this is because when we throttle the CPU of our node applications, it takes a very long time for them to start up — before any console.log put at the top of our application code kicks in (very scientific method). So that's what put me on this track.

[jeffijoe]

I had completely forgotten just how many files even a trivial JS server has to import. 😂

Yes so I'd recommend you use manual registrations. You can probably have an LLM write those for you, start by getting a map of the container.registrations, feed that to the LLM and have it generate the registration code for you.

To be honest, while loadModules is convenient, I have personally started manually registering modules for new projects, even those in other languages despite them supporting a similar automatic approach. It really doesn't take that long to add an extra line to a config somewhere whenever you do add a new module.

You could also invest in writing some code-gen. For example, you can use Awilix' listModules to then code-gen a function that registers all modules.