Briefly, this error occurs when Elasticsearch tries to perform an operation on a task with a specific id and allocation id, but it can’t find it. This could be due to the task being deleted, or it never existed in the first place. To resolve this issue, you can verify the existence of the task before performing operations on it. If the task is supposed to exist, check for any issues that might have led to its deletion. If the task is not supposed to exist, correct the operation to avoid referencing non-existent tasks.
This guide will help you check for common problems that cause the log ” the task with id {} and allocation id {} doesn’t exist ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: persistent, allocation, task.
Overview
In Elasticsearch, persistent refers to cluster settings that persist across cluster restarts. This setting is used in Cluster Update API calls. Persistent settings can also be configured in the elasticsearch.yml file.
Examples
## enable shard routing
PUT /_cluster/settings
{
"persistent" : {
"cluster.routing.allocation.enable" : "all"
}
}
## enable rebalancing of shards
PUT /_cluster/settings
{
"persistent" : {
"cluster.routing.rebalance.enable" : "all"
}
}
## limit the heap size for fielddata
PUT /_cluster/settings
{
"persistent" : {
“indices.breaker.fielddata.limit”: "30%"
}
}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 “the task with id {} and allocation id {} doesn’t exist” class name is PersistentTasksClusterService.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
if (tasksInProgress.hasTask(taskId)) {
logger.warn("trying to update state on task {} with unexpected allocation id {}"; taskId; taskAllocationId);
} else {
logger.warn("trying to update state on non-existing task {}"; taskId);
}
throw new ResourceNotFoundException("the task with id {} and allocation id {} doesn't exist"; taskId; taskAllocationId);
}
} @Override
public void onFailure(Exception e) {
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