Briefly, this error occurs when Elasticsearch is unable to start a rollup job due to a configuration issue or a system resource constraint. The rollup job ID mentioned in the error message can help identify the problematic job. To resolve this, you can check the configuration of the rollup job for any inconsistencies. If the configuration is correct, ensure that the system has enough resources (CPU, memory, disk space) to execute the job. If the issue persists, consider breaking the job into smaller tasks or increasing the system resources.
This guide will help you check for common problems that cause the log ” Cannot start task for Rollup Job [” + job.getConfig().getId() + “] because ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, task.
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.
Log Context
Log “Cannot start task for Rollup Job [” + job.getConfig().getId() + “] because” class name is RollupJobTask.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
*/ public synchronized void start(ActionListenerlistener) { final IndexerState prevState = indexer.getState(); if (prevState != IndexerState.STOPPED) { // fails if the task is not STOPPED listener.onFailure(new ElasticsearchException("Cannot start task for Rollup Job [" + job.getConfig().getId() + "] because" + " state was [" + prevState + "]")); return; } final IndexerState newState = indexer.start();
