failing_buildset_canceller old_build_canceller
Custom services are stateful components of Buildbot that can be added to the services key of the Buildbot config dictionary. The following is the services that are meant to be used without advanced knowledge of Buildbot.
FailingBuildsetCancellerOldBuildCanceller
More complex services are described in the developer section of the Buildbot manual. They are meant to be used by advanced users of Buildbot.