Support graceful process termination for GitLab Runner on Windows
Release notes
The ability to enable graceful shutdown on Windows is now available behind a feature flag. To enable, set the feature flag FF_USE_WINDOWS_LEGACY_PROCESS_STRATEGY to false.
Overview
Currently "graceful shutdown" - understood as Runner waiting for all executed jobs to exit before Runner process itself is finished - is supported only for Unix systems, where SIGQUIT signal can be sent to the process. Windows doesn't have such concept and currently process termination triggers the force-shutdown strategy where all executed jobs are interrupted.
We should start supporting "graceful shutdown" also for Windows.
Proposal
Introduce an optional way to turn down GitLab Runner in a three-times-interrupt strategy:
- Graceful waiting for jobs to finish and not accepting new jobs.
- First interrupt call (whether it's done by a Signal in Unix way or in the native Window way): would transfer runner to the graceful shutdown state. As a reminder: no new jobs are being requested and runner waits to finish all already handled jobs.
- More forceful shutdown, ensuring all jobs are killed.
- Second interrupt call that stops the graceful shutdown and forces runner to immediately stop all jobs. GitLAb Runner waits for the job to exit before turning down.
- Really forceful, kill Runner process and don't worry about jobs that might still be running.
- Third interrupt call immediately stops runner process and ignores the running jobs.
Detailed discussion here.