Improve build time

[anandthakker]

Follow-up to #6196

On my laptop, rebuilding takes about 7s:

• 3.2s to build rollup/build/{index,worker,chunk1}.js, and then
• 4s just to assemble these into the final bundle

That second step is much slower than it needs to be. It's using Rollup again, but only to make sure the sourcemaps for {index,worker,chunk1}.js get properly consumed/composed into the final sourcemap. This means we're wasting lots of time re-parsing these ast's even though it's not at all necessary.

[mourner]

Here's a perf profile for a build from scratch: https://gist.github.com/mourner/0acdc68648627ac431229d2ad601eefc

A quick scan seems to suggest there are some nice low hanging fruits there.

[anandthakker]

See also rollup/rollup#1553

[anandthakker]

Tracking with a project board here: https://github.com/mapbox/mapbox-gl-js/projects/11

[jfirebaugh]

Rollup 0.58.0 and later includes rollup/rollup#2119. We're currently on 0.57.1; however upgrading to 0.58.2 seems to break our solution for Web Workers:

$ /Users/john/Development/mapbox-gl-js/node_modules/.bin/rollup -c --environment BUILD:production

src/index.js, src/source/worker.js → rollup/build/mapboxgl...
(!) Circular dependency: src/style-spec/expression/parsing_context.js -> src/style-spec/expression/compound_expression.js -> src/style-spec/expression/parsing_context.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_function.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_function.js -> src/style-spec/validate/validate_object.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_function.js -> src/style-spec/validate/validate_array.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_layer.js -> src/style-spec/validate/validate_paint_property.js -> src/style-spec/validate/validate_property.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_layer.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/style-spec/validate/validate.js -> src/style-spec/validate/validate_light.js -> src/style-spec/validate/validate.js
(!) Circular dependency: src/geo/lng_lat_bounds.js -> src/geo/lng_lat.js -> src/geo/lng_lat_bounds.js
(!) Circular dependency: src/index.js -> src/ui/map.js -> src/style/style.js -> src/util/global_worker_pool.js -> src/util/worker_pool.js -> src/util/browser/web_worker.js -> src/index.js
(!) Circular dependency: src/index.js -> src/ui/map.js -> src/style/style.js -> src/util/global_worker_pool.js -> src/util/worker_pool.js -> src/index.js
created rollup/build/mapboxgl in 15.7s

rollup/mapboxgl.js → dist/mapbox-gl.js...
[!] Error: Could not resolve './build/mapboxgl/chunk1' from rollup/mapboxgl.js
Error: Could not resolve './build/mapboxgl/chunk1' from rollup/mapboxgl.js
    at error (/Users/john/Development/mapbox-gl-js/node_modules/rollup/dist/rollup.js:199:15)
    at /Users/john/Development/mapbox-gl-js/node_modules/rollup/dist/rollup.js:20674:25
    at <anonymous>

[mourner]

@guybedford does this ring a bell? Probably related to your recent chunk-related changes...

[guybedford]

@mourner no idea what that might be actually. It seems like the resolveId plugin function is not returning anything for that case. Let me know if you can isolate this a little more perhaps.

[anandthakker]

Writing from my phone so I haven’t checked this out, but I suspect this is because our two-step build process relies on knowing the name of the shared chunk emitted by the first step, and it looks like that name now includes a hash instead of just being “chunk1”. Note that the tree-shaking improvements won’t help our dev build time because we’re only doing tree shaking on prod builds

…

On Mon, Apr 30, 2018 at 11:35 AM Guy Bedford ***@***.***> wrote: @mourner <https://github.com/mourner> no idea what that might be actually. It seems like the resolveId plugin function is not returning anything for that case. Let me know if you can isolate this a little more perhaps. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#6309 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEvmRyaCj-31uEyvDLyYVtDPP4n0tJ-Mks5tty81gaJpZM4Sk1Nz> .

[guybedford]

Note a quick fix here would be to add chunkNames: '[alias].js' to the Rollup configuration, to avoid adding the hash.