Incremental `yarn bazel build //src:prodapp` time is not consistent.

🐞 bug report

Incremental yarn bazel build //src:prodapp time is not consistent in a new Angular Bazel project.

Is this a regression?

I don’t know

🔬 Minimal Reproduction

1. Create a new Angular Bazel app

yarn ng new bzl-app --collection=@angular/bazel

1. Build the project

yarn bazel build //src:prodapp # Or just yarn ng build

1. Repeating the following command

echo "" >> src/main.dev.ts && yarn bazel build //src:prodapp

If enough times, you’ll see two different build time:

pcloudy@pcloudy:~/workspace/angular_playground/bzl-app
$ echo "" >> src/main.dev.ts && yarn bazel build //src:prodapp
yarn run v1.12.3
warning ../package.json: No license field
$ /usr/local/google/home/pcloudy/workspace/angular_playground/bzl-app/node_modules/.bin/bazel build //src:prodapp
INFO: Analysed target //src:prodapp (1 packages loaded, 1 target configured).
INFO: Found 1 target...
Target //src:prodapp up-to-date:
  dist/bin/src/prodapp
INFO: Elapsed time: 15.826s, Critical Path: 15.01s
INFO: 5 processes: 3 linux-sandbox, 1 local, 1 worker.
INFO: Build completed successfully, 7 total actions
Done in 15.96s.

and

pcloudy@pcloudy:~/workspace/angular_playground/bzl-app
$ echo "" >> src/main.dev.ts && yarn bazel build //src:prodapp
yarn run v1.12.3
warning ../package.json: No license field
$ /usr/local/google/home/pcloudy/workspace/angular_playground/bzl-app/node_modules/.bin/bazel build //src:prodapp
INFO: Analysed target //src:prodapp (1 packages loaded, 1 target configured).
INFO: Found 1 target...
Target //src:prodapp up-to-date:
  dist/bin/src/prodapp
INFO: Elapsed time: 5.266s, Critical Path: 4.72s
INFO: 2 processes: 1 linux-sandbox, 1 worker.
INFO: Build completed successfully, 4 total actions
Done in 5.39s.

🌍 Your Environment

Angular Version:

pcloudy@pcloudy:~/workspace/angular_playground/bzl-app
$ yarn ng version
yarn run v1.12.3
warning ../package.json: No license field
$ ng version

     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI: 8.0.0-rc.2
Node: 10.15.3
OS: linux x64
Angular: 8.0.0-rc.2
... animations, bazel, cli, common, compiler, compiler-cli, core
... forms, language-service, platform-browser
... platform-browser-dynamic, router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.800.0-rc.2
@angular-devkit/build-angular     0.800.0-rc.2
@angular-devkit/build-optimizer   0.800.0-rc.2
@angular-devkit/build-webpack     0.800.0-rc.2
@angular-devkit/core              8.0.0-rc.2
@angular-devkit/schematics        8.0.0-rc.2
@ngtools/webpack                  8.0.0-rc.2
@schematics/angular               8.0.0-rc.2
@schematics/update                0.800.0-rc.2
rxjs                              6.4.0
typescript                        3.4.5
webpack                           4.30.0
    
Done in 0.57s.

Anything else relevant? This is also reproducible on Windows

pcloudy@pcloudy0-w MSYS ~/workspace/angular_playground/bzl-app
$ echo "" >> src/main.dev.ts && yarn bazel build //src:prodapp --experimental_generate_json_trace_profile
yarn run v1.12.3
warning ..\package.json: No license field
$ C:\tools\msys64\home\pcloudy\workspace\angular_playground\bzl-app\node_modules\.bin\bazel build //src:prodapp --experimental_generate_json_trace_profile
INFO: Writing tracer profile to 'C:/src/tmp/7qwhmymr/command.profile'
INFO: Reading 'startup' options from c:\users\pcloudy\.bazelrc: --output_user_root=C:/src/tmp
INFO: Options provided by the client:
  Inherited 'common' options: --isatty=1 --terminal_columns=320
INFO: Options provided by the client:
  'build' options: --python_path=C:/Python36/python.exe
INFO: Reading rc options for 'build' from c:\tools\msys64\home\pcloudy\workspace\angular_playground\bzl-app\.bazelrc:
  'build' options: --strategy=TypeScriptCompile=worker --strategy=AngularTemplateCompile=worker --symlink_prefix=dist/ --incompatible_strict_action_env --define=compile=legacy
INFO: Reading rc options for 'build' from c:\users\pcloudy\.bazelrc:
  'build' options: --curses=yes --color=yes --verbose_failures --announce_rc
INFO: Analysed target //src:prodapp (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //src:prodapp up-to-date:
  C:/src/tmp/7qwhmymr/execroot/project/bazel-out/x64_windows-fastbuild/bin/src/prodapp
INFO: Elapsed time: 22.983s, Critical Path: 21.78s
INFO: 5 processes: 4 local, 1 worker.
INFO: Build completed successfully, 7 total actions
Done in 23.29s.

pcloudy@pcloudy0-w MSYS ~/workspace/angular_playground/bzl-app
$ echo "" >> src/main.dev.ts && yarn bazel build //src:prodapp --experimental_generate_json_trace_profile
yarn run v1.12.3
warning ..\package.json: No license field
$ C:\tools\msys64\home\pcloudy\workspace\angular_playground\bzl-app\node_modules\.bin\bazel build //src:prodapp --experimental_generate_json_trace_profile
INFO: Writing tracer profile to 'C:/src/tmp/7qwhmymr/command.profile'
INFO: Reading 'startup' options from c:\users\pcloudy\.bazelrc: --output_user_root=C:/src/tmp
INFO: Options provided by the client:
  Inherited 'common' options: --isatty=1 --terminal_columns=320
INFO: Options provided by the client:
  'build' options: --python_path=C:/Python36/python.exe
INFO: Reading rc options for 'build' from c:\tools\msys64\home\pcloudy\workspace\angular_playground\bzl-app\.bazelrc:
  'build' options: --strategy=TypeScriptCompile=worker --strategy=AngularTemplateCompile=worker --symlink_prefix=dist/ --incompatible_strict_action_env --define=compile=legacy
INFO: Reading rc options for 'build' from c:\users\pcloudy\.bazelrc:
  'build' options: --curses=yes --color=yes --verbose_failures --announce_rc
INFO: Analysed target //src:prodapp (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //src:prodapp up-to-date:
  C:/src/tmp/7qwhmymr/execroot/project/bazel-out/x64_windows-fastbuild/bin/src/prodapp
INFO: Elapsed time: 7.474s, Critical Path: 6.27s
INFO: 2 processes: 1 local, 1 worker.
INFO: Build completed successfully, 4 total actions
Done in 7.78s.

You can add --experimental_generate_json_trace_profile to profile the build and use chrome://tracing to load and visualize the profile data. Here’s my result: Fast:

Slow:

Profile data is available here: profile.zip

[filipesilva]

@alxhub @manughub the CLI repository is not the correct repository for issues related to @angular/bazel. That package is developed in https://github.com/angular/angular/tree/master/packages/bazel. The angular/angular repository, where it was opened, was the correct place to open it.

cc @kyliau

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