Too many pending states pending – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-1.3

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Briefly, this error occurs when there are too many cluster state updates that are yet to be processed. This could be due to a slow network, overloaded master node, or large cluster state. To resolve this, you can consider increasing the ‘cluster.publish.timeout’ setting to allow more time for updates. Alternatively, you can reduce the number of cluster state updates by limiting the number of indices, shards, or mappings. Lastly, you can also consider upgrading your master node hardware or network to handle more load.

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This guide will help you check for common problems that cause the log ” too many pending states ([{}] pending) ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: discovery.

Log Context

Log “too many pending states ([{}] pending)” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 pendingStates.add(new ClusterStateContext(state));
 if (pendingStates.size() > maxQueueSize) {
 ClusterStateContext context = pendingStates.remove(0);
 logger.warn("dropping pending state [{}]. more than [{}] pending states."; context; maxQueueSize);
 if (context.committed()) {
 context.listener.onNewClusterStateFailed(new OpenSearchException("too many pending states ([{}] pending)"; maxQueueSize));
 }  /**


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