pub serve delay between "Serving..." and "Build completed"

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2108507?v=3" align="left" width="96" height="96"hspace="10"> Issue by dgrove
Originally opened as dart-lang/sdk#19150

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Running with tip of bleeding_edge, I'm seeing a delay of 6-7 seconds between the time that pub serve prints "Serving todomvc web on http://127.0.0.1:8080" and the time that it prints "Build completed successfully".

This is when running the TodoMVC sample in Dartium

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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This sounds like time being spent running the polymer transformers. Siggi, could they take 6-7s worth of time?

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cc @sigmundch.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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It could - when do you pub-build pub reports about 5-6 seconds running polymer on TodoMVC. Most of the time is running the resolver (which might be loading and analyzing the entire SDK).

I haven't tried, but we could provide a mock SDK to the analyzer that only contains what we need. But the analyzer might already have this planned.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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A bit of barback instrumenting seems to confirm this: running ScriptCompactor on web/index.html takes about 5.6s on my machine. I'll bump this over to polymer.

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cc @munificent.
Set owner to @sigmundch.
Removed Area-Pub label.
Added Area-Pkg, Pkg-Polymer labels.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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For now, I'm going to investigate making the build faster with a mock SDK for the analyzer as a temporary workaround, but long term, I believe we should invest in a solution that allow us to not run transformations when launching an app for development in Dartium.

Bob and I had a long brainstorming discussion this morning about what we could do to address this, but it requires non-trivial changes. For example, one attractive idea we had was to use the user-agent to decide how transformers are run, similar to namespaces ideas you had discussed in the past.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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FYI - here is a change that let us mock out the SDK. It's an improvement, but it's not perfect:

https://codereview.chromium.org/315813003/

It takes TodoMVC from 4.8s in my machine, to 2.7s. The analyzer still resolves the entire application. I could make mocks for parts of the libraries that are known to us (like polymer), but I'm not sure about that. It already feels brittle with the current change.

The ultimate solution is to be lazy and not run any of the transformers in TodoMVC.

See: issue #400

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2108507?v=3" align="left" width="48" height="48"hspace="10"> Comment by dgrove

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This is significantly improved by polymer 0.10.1 . There's still more to do, but we're in good shape for 1.5 .

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Removed this from the 1.5 milestone.
Removed Priority-High label.
Added Priority-Medium label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Added this to the Later milestone.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Removed this from the Later milestone.
Added this to the 1.6 milestone.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Removed this from the 1.6 milestone.
Added this to the Later milestone.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Added Polymer-P-2 label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Removed this from the Later milestone.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Removed Polymer-P-2 label.
Added Polymer-Milestone-Later label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="48" height="48"hspace="10"> Comment by sigmundch

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Removed Polymer-Milestone-Later label.
Added PolymerMilestone-Later label.

[jakemac53]

Nothing further planned on the polymer end of things for this.