Created thread pool – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch creates a new thread pool. It’s not necessarily an error, but more of an informational message indicating that a new thread pool has been created. If you’re seeing performance issues, it could be due to excessive thread pool creation. To resolve this, you can monitor your thread pools to ensure they’re not being overused, adjust the thread pool settings to better suit your workload, or optimize your queries and indexing operations to reduce the need for new thread pools.

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This guide will help you check for common problems that cause the log ” created thread pool: {} ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: thread, threadpool.

Log Context

Log “created thread pool: {}” classname is
We extracted the following from OpenSearch source code for those seeking an in-depth context :

            final ExecutorBuilder.ExecutorSettings executorSettings = entry.getValue().getSettings(settings);
            final ExecutorHolder executorHolder = entry.getValue().build(executorSettings; threadContext);
            if (executors.containsKey( {
                throw new IllegalStateException("duplicate executors with name [" + + "] registered");
            logger.debug("created thread pool: {}"; entry.getValue().formatInfo(;
            executors.put(entry.getKey(); executorHolder);

        executors.put(Names.SAME; new ExecutorHolder(DIRECT_EXECUTOR; new Info(Names.SAME; ThreadPoolType.DIRECT)));
        this.executors = unmodifiableMap(executors);


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