mirror of
https://github.com/honeymoose/OpenSearch.git
synced 2025-02-09 06:25:07 +00:00
99a7d8e41f
Only tasks that extend CancellableTask can be cancelled using this mechanism. If a cancellable task has children it can elect to cancel all child tasks as well. In this case a special ban parent request is sent to all nodes. This request does two things: 1) it prevents any tasks with the banned parent task from being started, and 2) it cancels all currently running tasks that have the banned task as a parent. The ban is lifted as soon as the coordinating node notifies all other nodes that the cancelled task has finished executing. If the coordinating node leaves the cluster before it has a chance to lift its bans, all bans set by this coordinating node are automatically removed. As an option a task can elect to automatically cancel all child tasks if their parent task was running on a node that just left the cluster. This option makes sense for cancellable heavy tasks that have no side-effects and only return results to the coordinating node. With the coordinating node gone, it doesn't make sense to run such tasks any longer since their results will be most likely discarded.