Parcel: 🐛 Bundle metrics showing incorrect time

[davidnagli]

🐛 bug report

🎛 Configuration (.babelrc, package.json, cli command)

parcel build ./examples/single-entry-med-graph-js-only/src/index.js -d ./examples/single-entry-med-graph-js-only/dist --no-minify --no-cache

🤔 Expected Behavior

Should show the right time

😯 Current Behavior

Shows 10.44s even though it reports ✨ Built in 3.48s. above it.

Based on reasonable judgement, it doesn’t take even close to 10 seconds. Just eyeballing it, the whole thing finishes in less than 4 or 5 seconds at most.

💁 Possible Solution

The bundle metrics feature was introduced in #733, so that would be a good place to start.

Bundle time get’s determined here:
https://github.com/parcel-bundler/parcel/blob/1ceb7aa791cc4a4a2291c1f78c799182f89fc111/src/Bundle.js#L137-L140

Here’s the --detailed-report:

💻 Code Sample

Repo: TheLarnkin/bundler-performance-benchmark

🌍 Your Environment

| Software | Version(s) |
| ---------------- | ---------- |
| Parcel | 1.6.2
| Node | v8.9.4
| npm/Yarn | 5.6.0/1.3.2
| Operating System | Mac OS High Sierra (10.13.2)

[lili21]

I can take a look.

[lili21]

I guess the problem is the assets are builded in parallel, and the bundle time is counted in serial

[fathyb]

Yeah @lili21 is right. You have 4 cores and 3 are used to build so 3.48s * 3 = 10.44s, see Jasper's comment on #733.

But I agree it can be confusing for most people. Maybe we should display the "parallel time" in the normal report and the "real time" in the detailled report.