Evergreen Aware Git Bisect

TLDR

bisect will print the last known passing version and first known failing version of mongo for a --branch, --variant and --lookback period, with respect to a user provided shell --script.

Usage

bisect can be invoked from within the mongo repo like so:

buildscripts/resmoke.py bisect
  --branch   ["master", "v5.1", "v5.0", etc.]
  --variant  ["enterprise-rhel-80-64-bit-dynamic-required", "ubuntu1804-debug-asan", etc.]
  --lookback [30, 90, 180, etc]
  --script    [shell script to indicate presence of bug]
  --python-installation [(optional) path to python3.7+]

To use this command, all that is needed is to write the shell --script which runs against a mongo version and returns 0 upon successful execution or non-zero upon failure. The --script will be run from within the build/resmoke-bisect/{version_id} directory described below.

Sample Script

set -e
python buildscripts/resmoke.py run --suites=sharding ./jstests/sharding/shard_aware_init.js

Bisect

All versions for the given --branch, --variant and --lookback period are fetched from Evergreen.

The repo, binaries, artifacts and virtual environment are downloaded to the build/resmoke-bisect directory for the middle version. This is what the build/resmoke-bisect directory may look like — where {version_id} is the github repo and bisect_venv is the virtual environment:

bisect_venv             {version_id}

This is what the build/resmoke-bisect/{version_id} directory may look like - where the binaries are downloaded.

all_feature_flags.txt  compile_expansions.yml etc                    jstests                mongoauditdecrypt      mongocryptd            mongodecrypt           mongoldap              mongos                 mqlrun                 wt
buildscripts           dist-test              evergreen              mongo                  mongobridge            mongod                 mongokerberos          mongoqd                mongotmock             src

The --script is run from within this build/resmoke-bisect/{version_id} directory. If it completes successfully, bisect continues on newer versions. Else, if it fails, bisect continues on older versions. This is repeated until the algorithm completes.

The last known passing version and first known failing version are print to stdout.

Notes

1. This bisect command assumes a perfect partition between passing & failing versions. ie: [Pass, Pass, Pass, Fail, Fail, Fail]. If there is not a perfect partition, this command will not work as expected. If there is not a perfect partition, try modifying the --lookback period or shell --script.

2. Bisecting to beyond a year may not be supported since Evergreen artifacts are only stored for a year.

3. Older versions will have different syntax, so you may need to run resmoke.py instead of resmoke.py run if the latter fails in the shell script.

Help

buildscripts/resmoke.py bisect --help