Elasticsearch Elasticsearch Long Running Bulk Index Task

By Opster Team

Updated: Jul 5, 2023

| 2 min read

What does this mean? 

A long running bulk index task in Elasticsearch refers to a situation where the process of indexing a large amount of data takes an unusually long time to complete. This can lead to performance issues within the Elasticsearch cluster, as it may consume a significant amount of resources and affect the overall efficiency of the system.

This issue is monitored by Opster AutoOps in real-time with personalized recommendations provided for your own system. You can also configure notifications to avoid this issue forming in the future.

Why does this occur?

There could be several reasons behind the occurrence of a long running bulk index task in Elasticsearch. Some of the common factors include:

  1. Large bulk size: Indexing a large amount of data in a single bulk request can lead to longer processing times.
  2. Inefficient index mappings and analysis: Poorly configured index mappings and analysis settings can result in slow indexing performance.
  3. Low refresh interval: A low refresh interval can cause Elasticsearch to spend more time refreshing the index, leading to longer indexing times.

Possible impact and consequences of long running bulk index tasks

The impact of a long running bulk index task in Elasticsearch can be significant, as it may affect the cluster performance. Some of the potential consequences include:

  1. Slower search and query performance: As the cluster resources are consumed by the long running bulk index task, the search and query performance may be negatively affected.
  2. Increased resource usage: The long running task can lead to higher CPU, memory, and disk usage, which can impact the overall performance of the Elasticsearch cluster.
  3. Reduced availability: In extreme cases, the long running bulk index task may cause the cluster to become unresponsive or unavailable, leading to downtime and potential data loss.

How to resolve

To resolve the issue of a long running bulk index task in Elasticsearch, consider the following recommendations:

1. Improve the long-running bulk index tasks: Divide the bulk index into smaller batches to reduce the processing time. You can also check the bulk size to improve performance.

2. Increase the refresh interval: If the refresh interval is currently less than 30 seconds, increase it to 30 seconds to reduce the frequency of index refreshes and improve performance.

To update the refresh interval of an index, use the following command:

PUT /your_index_name/_settings
  "index" : {
    "refresh_interval" : "30s"

3. Review the index mappings and analysis: Optimize the index mappings and analysis settings to ensure efficient indexing performance. You can use the free Opster Template Analyzer tool to help you with this.

4. Monitor cluster performance: Regularly monitor the performance of your Elasticsearch cluster to identify and address any potential issues before they escalate.


By following this guide, you should be able to identify and resolve the issue of long running bulk index tasks in Elasticsearch. By implementing the recommended solutions, you can improve the performance of your Elasticsearch cluster and ensure efficient indexing of your data.

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