Flaky tests are reported in a separate step on the bots (example build).

Each test log provides a pre-filled command line for triggering an automated flake bisect, like:
Trigger flake bisect on command line:
echo '{"bisect_buildername": "V8 Linux64 - verify csa", "bisect_mastername": "client.v8", "build_config": "Release", "extra_args": [], "isolated_name": "bot_default", "swarming_dimensions": ["cpu:x86-64", "gpu:none", "os:Ubuntu-14.04", "pool:Chrome"], "test_name": "inspector/runtime/command-line-api-without-side-effects", "timeout_sec": 60, "to_revision": "7f51fdac5bc8bf28b30904e1601819b356187b43", "total_timeout_sec": 120, "variant": "nooptimization"}' | buildbucket.py put -b luci.v8.try -n v8_flako -p -

Before triggering flake bisects for the first time, users must log in with a google.com account:
depot-tools-auth login https://cr-buildbucket.appspot.com

Then execute the provided command line, which returns a build URL running flake bisect (example).

If you're in luck, bisect will point you to a suspect. If not, you might wanna read further...

Properties for customizing flake bisect

  • bisect_buildername: Master name of the builder that produced the builds for bisection.
  • bisect_mastername: Name of the builder that produced the builds for bisection.
  • build_config: Build config passed to V8's run-tests.py script (there the parameter name is --mode, example: Release or Debug).
  • extra_args: Extra arguments passed to V8's run-tests.py script.
  • isolated_name: Name of the isolated file (e.g. bot_default, mjsunit).
  • repetitions: Initial number of test repetitions (passed to run-tests.py's --random-seed-stress-count option; unused if total_timeout_sec is used).
  • swarming_dimensions: Swarming dimensions classifying the type of bot the tests should run on. Passed as list of strings, each in the format name:value.
  • test_name: Fully qualified test name passed to run-tests.py. E.g. mjsunit/foobar.
  • timeout_sec: Timeout parameter passed to run-tests.py.
  • to_revision: Revision known to be bad, where backwards bisection will start.
  • total_timeout_sec: Initial total timeout for one entire bisect step. During calibration, this time is doubled several times if needed. Set to 0 to disable and use the ‘repetitions’ property instead.
  • variant: Name of the testing variant passed to run-tests.py.