Opster Team
Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.
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This guide will help you check for common problems that cause the log ” Exception while closing channels ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: handler.

Log Context
Log “exception while closing channels” classname is AbstractHttpServerTransport.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
synchronized (httpServerChannels) { if (httpServerChannels.isEmpty() == false) { try { CloseableChannel.closeChannels(new ArrayList(httpServerChannels); true); } catch (Exception e) { logger.warn("exception while closing channels"; e); } finally { httpServerChannels.clear(); } } }
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Arpit Ghiya
Senior Lead SRE at Coupa