Grok pattern matching timed out – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 8.7-8.9

Briefly, this error occurs when Elasticsearch’s Grok processor takes too long to match a pattern in a large input string, causing a timeout. This is often due to complex or inefficient Grok patterns. To resolve this issue, you can optimize your Grok patterns to be more efficient, reduce the size of the input string, or increase the timeout setting. However, increasing the timeout should be a last resort as it could impact overall system performance.

This guide will help you check for common problems that cause the log ” Grok pattern matching timed out ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “Grok pattern matching timed out” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 String redacted = matchRedact(fieldValue; groks; redactedStartToken; redactedEndToken);
 ingestDocument.setFieldValue(redactField; redacted);
 return ingestDocument;
 } catch (RuntimeException e) {
 // grok throws a RuntimeException when the watchdog interrupts the match
 throw new ElasticsearchTimeoutException("Grok pattern matching timed out"; e);
 }  @Override
 public String getType() {


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