PoC loading of specific parts of core-js

[mstoykov]

This is a very WIP alternative to #1714 that actually loads specific files from it and it is obvious what is loaded in the code instead of needing to know how we build the shim file.

TODO:

• Discuss if this is at all useful ... The main benefit is that if tomorrow we decide to drop es6.promise.js we just drop it from the index.js and then drop it dependencies.
• Better code - again this is PoC - I intend for there to be a test that does the checking if some files are not needed for example, but also very likely to refactor the whole code ;). Also it will be nice if the source codes are compiled only once.
• Decide if we want to drop even more corejs? The nice thing here is that you also can see which files are imported as dependencies
• Make some script that does the git checkout + copy of the concrete files we need and runs go generate to embed them, without actually adding the files to the repo. This will save some space

Problems:

• This actually generates a bigger binary, and the rice-box.go is bigger as we have slightly more code actually.
• It is probably slightly slower as it needs to require some stuff, haven't benchmarked it yet.

[codecov-io]

Codecov Report

Merging #1732 (ff2e0c8) into master (6081e6a) will increase coverage by 1.40%.
The diff coverage is 83.90%.

@@            Coverage Diff             @@
##           master    #1732      +/-   ##
==========================================
+ Coverage   71.49%   72.90%   +1.40%     
==========================================
  Files         178      178              
  Lines       13727    14518     +791     
==========================================
+ Hits         9814    10584     +770     
- Misses       3301     3317      +16     
- Partials      612      617       +5     

Flag	Coverage Δ
ubuntu	72.88% <83.90%> (+1.44%)	⬆️
windows	71.52% <83.90%> (+1.48%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
js/bundle.go	90.54% <0.00%> (ø)
js/lib/rice-box.go	100.00% <ø> (ø)
js/lib/lib.go	77.65% <84.88%> (-22.35%)	⬇️
lib/executor/vu_handle.go	93.33% <0.00%> (-1.91%)	⬇️
lib/testutils/minirunner/minirunner.go	86.04% <0.00%> (+4.65%)	⬆️

---

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[mstoykov]

Some performance running

import http from "k6/http";
import { sleep } from "k6";

export let options = {
    discardResponseBodies: true,
}
export default function() {
    http.get("https://httpbin.test.loadimpact.com/get");
    sleep(Math.random() * 2 + 3);
}

with -vus 5000 --duration 60s main.js -v --no-thresholds --no-summary

version	iterations	mem usage	CPU usage	time to initialize VUs	run time
6081e6a	64391	17066648	440%	~29.5s	1:54.10
stripCoreJs	64430	8201408	345%	~10.45s	1:39.45
ddf9ecd	65892	6659656	386%	~10.8s	1:29.55
1d0812c	65229	5189428	314%	~10.07	1:37.07
6081e6a + base	62436	2607824	333%	~2.1s	1:14.58

The first is ( the current ) master, stripCoreJs is #1714 rebased on it, and the last is the current last commit here.

• 6081e6a + base is the master + compatibility-mode=base + a script changes that can work with it .
• around 1GB is added to the mem usage, during the 1 minute of execution.

The numbers move a little bit, but are in the same magnitude.

I don't know why stripCoreJS uses more memory, maybe I dropped something additional or web packing adds a lot of additional stuff?

[simskij]

Yeah, webpack adds some code, but it should be fairly insignificant in this case. I need to take this branch for a drive before having anything useful to say. Will get back to you! Good job nonetheless! 👍

[mstoykov]

close in favor of #1772