Elasticsearch Error: Too many dynamic script compilations - Common Causes & Fixes

Brief Explanation

The "Too many dynamic script compilations" error in Elasticsearch occurs when the number of script compilations exceeds the configured limit within a certain time window. This error is a protective measure to prevent excessive resource consumption due to frequent script compilations.

Common Causes

1. Frequent use of ad-hoc scripts in queries or aggregations
2. Poorly optimized scripts that require frequent recompilation
3. Insufficient script cache size
4. Misconfigured script compilation circuit breaker settings
5. High volume of unique scripts being submitted to Elasticsearch

Troubleshooting and Resolution Steps

1. Identify problematic scripts: Use the Elasticsearch API to identify which scripts are being compiled frequently.

2. Optimize scripts: Refactor frequently used scripts to be more efficient and reusable.

3. Increase script cache size: Adjust the script.cache.max_size setting to allow more compiled scripts to be cached.

4. Adjust circuit breaker settings: Modify the script.max_compilations_rate setting to allow more compilations per time window.

5. Use stored scripts: Convert frequently used dynamic scripts to stored scripts to reduce compilation overhead.

6. Monitor and analyze: Implement monitoring to track script compilation rates and identify patterns or spikes.

7. Update Elasticsearch: Ensure you're running the latest version of Elasticsearch, as newer versions often include improvements in script handling and performance.

Additional Information

• Consider using the Painless scripting language, which is designed for better performance and security in Elasticsearch.
• Regularly review and optimize your queries and aggregations to minimize the need for complex scripts.
• Use the Script API to manage and monitor stored scripts effectively.

Frequently Asked Questions

Q: How can I check the current script compilation rate?
A: You can check the current compilation rate using the /_nodes/stats/script API endpoint, which provides statistics on script compilations and cache usage.

Q: What is a safe value for script.max_compilations_rate?
A: The safe value depends on your specific use case and cluster resources. Start with the default (75/5m) and adjust gradually while monitoring performance. A common range is between 50-150 compilations per 5-minute window.

Q: Can I disable the script compilation circuit breaker?
A: While it's possible to set script.max_compilations_rate to 0 to disable the circuit breaker, it's not recommended as it can lead to resource exhaustion and cluster instability.

Q: How do stored scripts help with this error?
A: Stored scripts are pre-compiled and cached, eliminating the need for repeated compilations. This reduces the likelihood of hitting the compilation limit and improves overall performance.

Q: Are there any performance differences between different scripting languages in Elasticsearch?
A: Yes, Painless is generally the most performant and secure scripting language in Elasticsearch. Other languages like Groovy or JavaScript (if enabled) may have different performance characteristics and security implications.