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class="navGroups"><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Getting started<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.23.0/design/index.html">Introduction to Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/tutorials/index.html">Quickstart</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/tutorials/docker.html">Docker</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/single-server.html">Single server deployment</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/tutorials/cluster.html">Clustered deployment</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Tutorials<span class="arrow"><svg 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href="/docs/0.23.0/ingestion/compaction.html">Compaction</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Stream ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/extensions-core/kafka-ingestion.html">Apache Kafka ingestion</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/extensions-core/kafka-supervisor-reference.html">Apache Kafka supervisor</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/extensions-core/kafka-supervisor-operations.html">Apache Kafka operations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/extensions-core/kinesis-ingestion.html">Amazon Kinesis</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Batch ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/ingestion/native-batch.html">Native batch</a></li><li class="navListItem"><a 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driver API</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/sql-query-context.html">SQL query context</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/sql-metadata-tables.html">SQL metadata tables</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/sql-translation.html">SQL query translation</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/querying.html">Native queries</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/query-execution.html">Query execution</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/0.23.0/querying/troubleshooting.html">Troubleshooting</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Concepts</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/datasource.html">Datasources</a></li><li class="navListItem"><a class="navItem" 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href="/docs/0.23.0/querying/granularities.html">Granularities</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/dimensionspecs.html">Dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/aggregations.html">Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/post-aggregations.html">Post-aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/misc/math-expr.html">Expressions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/having.html">Having filters (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/limitspec.html">Sorting and limiting (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/topnmetricspec.html">Sorting (topN)</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/sorting-orders.html">String comparators</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/querying/virtual-columns.html">Virtual columns</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/geo.html">Spatial filters</a></li></ul></div></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Configuration<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.23.0/configuration/index.html">Configuration reference</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/extensions.html">Extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/configuration/logging.html">Logging</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Operations<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/druid-console.html">Web console</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/getting-started.html">Getting started with Apache Druid</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Security</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/security-overview.html">Security overview</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/security-user-auth.html">User authentication and authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/auth-ldap.html">LDAP auth</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/password-provider.html">Password providers</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/dynamic-config-provider.html">Dynamic Config Providers</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/tls-support.html">TLS support</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Performance tuning</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/basic-cluster-tuning.html">Basic cluster tuning</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/segment-optimization.html">Segment Size Optimization</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/mixed-workloads.html">Mixed workloads</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/http-compression.html">HTTP compression</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/clean-metadata-store.html">Automated metadata cleanup</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Monitoring</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/request-logging.html">Request logging</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/metrics.html">Metrics</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/alerts.html">Alerts</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/api-reference.html">API reference</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/high-availability.html">High availability</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/rolling-updates.html">Rolling updates</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/rule-configuration.html">Retaining or automatically dropping data</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/other-hadoop.html">Working with different versions of Apache Hadoop</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Misc</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/management-uis.html">Legacy Management UIs</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/dump-segment.html">dump-segment tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/reset-cluster.html">reset-cluster tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/insert-segment-to-db.html">insert-segment-to-db tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/pull-deps.html">pull-deps tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/deep-storage-migration.html">Deep storage migration</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/export-metadata.html">Export Metadata Tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/metadata-migration.html">Metadata Migration</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/operations/use_sbt_to_build_fat_jar.html">Content for build.sbt</a></li></ul></div></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Development<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/overview.html">Developing on Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/0.23.0/development/modules.html">Creating extensions</a></li><li class="navListItem"><a 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| <p>This topic describes issues that may affect query execution in Druid, how to identify those issues, and strategies to resolve them.</p> |
| <h2><a class="anchor" aria-hidden="true" id="query-fails-due-to-internal-communication-timeout"></a><a href="#query-fails-due-to-internal-communication-timeout" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Query fails due to internal communication timeout</h2> |
| <p>In Druid's query processing, when the Broker sends a query to the data servers, the data servers process the query and push their intermediate results back to the Broker. |
| Because calls from the Broker to the data servers are synchronous, the Jetty server can time out in data servers in certain cases:</p> |
| <ol> |
| <li>The data servers don't push any results to the Broker before the maximum idle time.</li> |
| <li>The data servers started to push data but paused for longer than the maximum idle time such as due to <a href="/docs/0.23.0/operations/basic-cluster-tuning.html#broker-backpressure">Broker backpressure</a>.</li> |
| </ol> |
| <p>When such timeout occurs, the server interrupts the connection between the Broker and data servers which causes the query to fail with a channel disconnection error. For example,</p> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"error"</span>: { |
| <span class="hljs-attr">"error"</span>: <span class="hljs-string">"Unknown exception"</span>, |
| <span class="hljs-attr">"errorMessage"</span>: <span class="hljs-string">"Query[6eee73a6-a95f-4bdc-821d-981e99e39242] url[https://localhost:8283/druid/v2/] failed with exception msg [Channel disconnected] (through reference chain: org.apache.druid.query.scan.ScanResultValue[\"segmentId\"])"</span>, |
| <span class="hljs-attr">"errorClass"</span>: <span class="hljs-string">"com.fasterxml.jackson.databind.JsonMappingException"</span>, |
| <span class="hljs-attr">"host"</span>: <span class="hljs-string">"localhost:8283"</span> |
| } |
| } |
| </code></pre> |
| <p>Channel disconnection occurs for various reasons. |
| To verify that the error is due to web server timeout, search for the query ID in the Historical logs. |
| The query ID in the example above is <code>6eee73a6-a95f-4bdc-821d-981e99e39242</code>. |
| The <code>"host"</code> field in the error message above indicates the IP address of the Historical in question. |
| In the Historical logs, you will see a raised exception indicating <code>Idle timeout expired</code>:</p> |
| <pre><code class="hljs css language-text">2021-09-14T19:52:27,685 ERROR [qtp475526834-85[scan_[test_large_table]_6eee73a6-a95f-4bdc-821d-981e99e39242]] org.apache.druid.server.QueryResource - Unable to send query response. (java.io.IOException: java.util.concurrent.TimeoutException: Idle timeout expired: 300000/300000 ms) |
| 2021-09-14T19:52:27,685 ERROR [qtp475526834-85] org.apache.druid.server.QueryLifecycle - Exception while processing queryId [6eee73a6-a95f-4bdc-821d-981e99e39242] (java.io.IOException: java.util.concurrent.TimeoutException: Idle timeout expired: 300000/300000 ms) |
| 2021-09-14T19:52:27,686 WARN [qtp475526834-85] org.eclipse.jetty.server.HttpChannel - handleException /druid/v2/ java.io.IOException: java.util.concurrent.TimeoutException: Idle timeout expired: 300000/300000 ms |
| </code></pre> |
| <p>To mitigate query failure due to web server timeout:</p> |
| <ul> |
| <li>Increase the max idle time for the web server. |
| Set the max idle time in the <code>druid.server.http.maxIdleTime</code> property in the <code>historical/runtime.properties</code> file. |
| You must restart the Druid cluster for this change to take effect. |
| See <a href="/docs/0.23.0/configuration/index.html">Configuration reference</a> for more information on configuring the server.</li> |
| <li>If the timeout occurs because the data servers have not pushed any results to the Broker, consider optimizing data server performance. Significant slowdown in the data servers may be a result of spilling too much data to disk in <a href="/docs/0.23.0/querying/groupbyquery.html#performance-tuning-for-groupby-v2">groupBy v2 queries</a>, large <a href="/docs/0.23.0/querying/filters.html#in-filter"><code>IN</code> filters</a> in the query, or an under scaled cluster. Analyze your <a href="/docs/0.23.0/operations/metrics.html#query-metrics">Druid query metrics</a> to determine the bottleneck.</li> |
| <li>If the timeout is caused by Broker backpressure, consider optimizing Broker performance. Check whether the connection is fast enough between the Broker and deep storage.</li> |
| </ul> |
| </span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/0.23.0/querying/query-execution.html"><span class="arrow-prev">← </span><span>Query execution</span></a><a class="docs-next button" href="/docs/0.23.0/querying/datasource.html"><span>Datasources</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#query-fails-due-to-internal-communication-timeout">Query fails due to internal communication timeout</a></li></ul></nav></div><footer class="nav-footer druid-footer" id="footer"><div class="container"><div class="text-center"><p><a href="/technology">Technology</a> · <a href="/use-cases">Use Cases</a> · <a href="/druid-powered">Powered by Druid</a> · <a href="/docs/0.23.0/latest">Docs</a> · <a href="/community/">Community</a> · <a href="/downloads.html">Download</a> · <a href="/faq">FAQ</a></p></div><div class="text-center"><a title="Join the user group" href="https://groups.google.com/forum/#!forum/druid-user" target="_blank"><span class="fa fa-comments"></span></a> · <a title="Follow Druid" href="https://twitter.com/druidio" target="_blank"><span class="fab fa-twitter"></span></a> · <a title="Download via Apache" href="https://www.apache.org/dyn/closer.cgi?path=/incubator/druid/{{ site.druid_versions[0].versions[0].version }}/apache-druid-{{ site.druid_versions[0].versions[0].version }}-bin.tar.gz" target="_blank"><span class="fas fa-feather"></span></a> · <a title="GitHub" href="https://github.com/apache/druid" target="_blank"><span class="fab fa-github"></span></a></div><div class="text-center license">Copyright © 2019 <a href="https://www.apache.org/" target="_blank">Apache Software Foundation</a>.<br/>Except where otherwise noted, licensed under <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA 4.0</a>.<br/>Apache Druid, Druid, and the Druid logo are either registered trademarks or trademarks of The Apache Software Foundation in the United States and other countries.</div></div></footer></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script> |
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