Briefly, this error occurs when Elasticsearch’s Watcher feature pauses the execution of a watch due to an overload of queued tasks. This is a mechanism to prevent system overload. To resolve this issue, you can consider increasing the thread pool size or the queue size. Alternatively, you can optimize your watches to run less frequently or make them less resource-intensive. Also, ensure that your Elasticsearch cluster has sufficient resources to handle the workload.
This guide will help you check for common problems that cause the log ” paused watch execution; reason [{}]; cancelled [{}] queued tasks ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.
Log Context
Log “paused watch execution; reason [{}]; cancelled [{}] queued tasks” classname is WatcherService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
* manual watch execution; i.e. via the execute watch API
*/
public void pauseExecution(String reason) {
triggerService.pauseExecution();
int cancelledTaskCount = executionService.pause(() -> {});
logger.info("paused watch execution; reason [{}]; cancelled [{}] queued tasks"; reason; cancelledTaskCount);
}
/**
* This reads all watches from the .watches index/alias and puts them into memory for a short period of time;
* before they are fed into the trigger service.
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