Briefly, this error occurs when Elasticsearch Machine Learning (ML) jobs are in a deleting state but the deletion task fails. This could be due to insufficient permissions, network issues, or system resource constraints. To resolve this, you can try the following: 1) Check and adjust user permissions to ensure the task can be executed. 2) Investigate network connectivity and stability. 3) Monitor system resources and increase capacity if necessary. 4) Restart the Elasticsearch cluster to clear any temporary issues. Always ensure to backup your data before making any major changes.
This guide will help you check for common problems that cause the log ” [ML] maintenance task: triggerDeleteJobsInStateDeletingWithoutDeletionTask failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, task, delete.
Overview
A task is an Elasticsearch operation, which can be any request performed on an Elasticsearch cluster, such as a delete by query request, a search request and so on. Elasticsearch provides a dedicated Task API for the task management which includes various actions, from retrieving the status of current running tasks to canceling any long running task.
Examples
Get all currently running tasks on all nodes of the cluster
Apart from other information, the response of the below request contains task IDs of all the tasks which can be used to get detailed information about the particular task in question.
GET _tasks
Get detailed information of a particular task
Where clQFAL_VRrmnlRyPsu_p8A:1132678759 is the ID of the task in below request
GET _tasks/clQFAL_VRrmnlRyPsu_p8A:1132678759
Get all the current tasks running on particular nodes
GET _tasks?nodes=nodeId1,nodeId2
Cancel a task
Where clQFAL_VRrmnlRyPsu_p8A:1132678759 is the ID of the task in the below request
POST /_tasks/clQFAL_VRrmnlRyPsu_p8A:1132678759/_cancel?pretty
Notes
- The Task API will be most useful when you want to investigate the spike of resource utilization in the cluster or want to cancel an operation.
Overview
DELETE is an Elasticsearch API which removes a document from a specific index. This API requires an index name and _id document to delete the document.
Delete a document
DELETE /my_index/_doc/1
Notes
- A delete request throws 404 error code if the document does not already exist in the index.
- If you want to delete a set of documents that matches a query, you need to use delete by query API.
Log Context
Log “[ML] maintenance task: triggerDeleteJobsInStateDeletingWithoutDeletionTask failed” classname is MlDailyMaintenanceService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
// Step 2: Delete expired data
ActionListener deleteJobsListener = ActionListener.wrap(
unused -> triggerDeleteExpiredDataTask(finalListener);
e -> {
logger.info("[ML] maintenance task: triggerDeleteJobsInStateDeletingWithoutDeletionTask failed"; e);
// Note: Steps 1 and 2 are independent of each other and step 2 is executed even if step 1 failed.
triggerDeleteExpiredDataTask(finalListener);
}
);
