Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.
To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.
This guide will help you check for common problems that cause the log ” Failed to reassign persistent tasks ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster and persistent.
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%"
}
}
Log Context
Log “Failed to reassign persistent tasks” classname is PersistentTasksClusterService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
return reassignTasks(currentState);
}
Override
public void onFailure(String source; Exception e) {
logger.warn("failed to reassign persistent tasks"; e);
// There must be a task that's worth rechecking because there was one
// that caused this method to be called and the method failed to assign it
periodicRechecker.rescheduleIfNecessary();
}
Find & fix Elasticsearch problems
