Profiling Build Times with Bazel

[louwers]

Cool Bazel feature: you can produce a JSON Trace Profile to see what is taking up most time when making a build with Bazel.

For example, here is how I generated a profile for the //platform/ios:App target.

bazel build --profile=/tmp/profile4.json.gz \
--experimental_profile_include_target_label \
--disk_cache= \
--noremote_accept_cached //platform/ios:App

Open in Chrome:

chrome://tracing or https://ui.perfetto.dev/

Drag and drop the generated file.

Results in the following: