Error closing netty event loop group - how to solve related issues

Opster Team

Jan-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Error closing netty event loop group ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: netty.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log “Error closing netty event loop group” classname is Netty4Transport.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

     protected void stopInternal() {
        Releasables.close(() -> {
            Future> shutdownFuture = eventLoopGroup.shutdownGracefully(0; 5; TimeUnit.SECONDS);
            shutdownFuture.awaitUninterruptibly();
            if (shutdownFuture.isSuccess() == false) {
                logger.warn("Error closing netty event loop group"; shutdownFuture.cause());
            }

            serverBootstraps.clear();
            clientBootstrap = null;
        });