Elasticsearch CircuitBreakingException: Data exceeded memory limits

Brief Explanation

The CircuitBreakingException with the message "Data exceeded memory limits" occurs in Elasticsearch when the amount of data being processed exceeds the configured memory limits. This error is triggered by Elasticsearch's circuit breaker mechanism, which is designed to prevent out-of-memory errors and maintain cluster stability.

Common Causes

1. Insufficient memory allocation for Elasticsearch
2. Large, complex queries or aggregations
3. Indexing or bulk operations with large payloads
4. Poorly optimized mappings or index settings
5. Misconfigured circuit breaker settings

Troubleshooting and Resolution Steps

1. Increase JVM heap size:

   • Only applicable if JVM heap is below 30gb and 50% of machine memory
   • Modify the jvm.options file to increase the heap size, ensuring it doesn't exceed 50% of available RAM.
   • Example: -Xms4g -Xmx4g

2. Optimize queries and aggregations:

   • Review and refactor complex queries.
   • Use pagination to limit result set sizes.
   • Implement filter aggregations where possible.

3. Adjust circuit breaker settings:

   • Modify elasticsearch.yml to increase circuit breaker limits.
   • Example: indices.breaker.total.limit: 70%

4. Optimize index mappings:

   • Review field mappings and remove unnecessary fields.
   • Use appropriate data types to reduce memory usage.

5. Monitor and analyze cluster performance:

   • Use Elasticsearch monitoring tools to identify resource-intensive operations.
   • Analyze slow logs to pinpoint problematic queries.

6. Scale your cluster:

   • Add more nodes to distribute data and processing load.

Additional Information and Best Practices

• Regularly monitor your cluster's memory usage and performance metrics.
• Implement proper capacity planning and scaling strategies.
• Use the Elasticsearch CAT API to get insights into cluster health and resource usage.
• Consider using index lifecycle management (ILM) to manage data retention and reduce overall data volume.

Q&A Section

1. Q: What is the circuit breaker in Elasticsearch? A: The circuit breaker is a mechanism in Elasticsearch that estimates memory usage of operations and stops them if they would cause an out-of-memory error.

2. Q: How can I view current circuit breaker statistics? A: Use the GET /_nodes/stats/breaker API endpoint to view current circuit breaker statistics for all nodes.

3. Q: Are there different types of circuit breakers in Elasticsearch? A: Yes, Elasticsearch has several circuit breakers, including parent, fielddata, request, and in-flight request breakers.

4. Q: Can increasing the JVM heap size always solve CircuitBreakingExceptions? A: Not always. While increasing heap size can help, it's important to address the root cause, such as optimizing queries or improving data models.

5. Q: How does the circuit breaker relate to the Elasticsearch cache? A: The circuit breaker monitors memory usage across various Elasticsearch operations, including caching. Excessive cache usage can trigger circuit breaker exceptions.