Updating max thread count from to – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 1.3-1.3

Briefly, this error occurs when Elasticsearch is trying to update the maximum thread count but the new value is not specified or is invalid. This could be due to a configuration issue or a problem with the underlying system resources. To resolve this issue, you can check the Elasticsearch configuration for the thread pool settings and ensure they are set correctly. If the problem persists, you may need to check the system resources and ensure there are enough resources available for Elasticsearch to operate efficiently.

This guide will help you check for common problems that cause the log ” updating [max_thread_count] from [{}] to [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index and merge.

Log Context

Log “updating [max_thread_count] from [{}] to [{}]” classname is ConcurrentMergeSchedulerProvider.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

     class ApplySettings implements IndexSettingsService.Listener {
        public void onRefreshSettings(Settings settings) {
            int maxThreadCount = settings.getAsInt("index.merge.scheduler.max_thread_count"; ConcurrentMergeSchedulerProvider.this.maxThreadCount);
            if (maxThreadCount != ConcurrentMergeSchedulerProvider.this.maxThreadCount) {
                logger.info("updating [max_thread_count] from [{}] to [{}]"; ConcurrentMergeSchedulerProvider.this.maxThreadCount; maxThreadCount);
                ConcurrentMergeSchedulerProvider.this.maxThreadCount = maxThreadCount;
                for (CustomConcurrentMergeScheduler scheduler : schedulers) {
                    scheduler.setMaxMergesAndThreads(ConcurrentMergeSchedulerProvider.this.maxMergeCount; maxThreadCount);


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