[GitHub] [druid] jihoonson commented on a change in pull request #12128: Docs for cluster tiering to improve query concurrency

[GitBox <gi...@apache.org>]

jihoonson commented on a change in pull request #12128:
URL: https://github.com/apache/druid/pull/12128#discussion_r779923767



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File path: docs/operations/query-concurrency.md
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@@ -0,0 +1,174 @@
+---
+id: query-concurrency
+title: Query concurrency
+sidebar_label: Query concurrency
+---
+
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one
+  ~ or more contributor license agreements.  See the NOTICE file
+  ~ distributed with this work for additional information
+  ~ regarding copyright ownership.  The ASF licenses this file
+  ~ to you under the Apache License, Version 2.0 (the
+  ~ "License"); you may not use this file except in compliance
+  ~ with the License.  You may obtain a copy of the License at
+  ~
+  ~   http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing,
+  ~ software distributed under the License is distributed on an
+  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  ~ KIND, either express or implied.  See the License for the
+  ~ specific language governing permissions and limitations
+  ~ under the License.
+  -->
+
+If you frequently run concurrent, mixed workloads on your Druid cluster, configure Druid to properly allocate cluster resources and optimize your overall query performance. With proper resource isolation, you can execute long-running, low priority queries that are resource intensive without interfering with short-running, high priority queries that require fewer resources. By separating cluster resources, you prevent queries from competing with each other for resources such as CPU, memory, and network access.
+
+There are two approaches to isolate your resources for improving query concurrency: query laning and cluster tiering. Use query laning to set a limit on the maximum number of long-running queries executed on each Broker. Use cluster tiering to define separate groups of Historicals and Brokers to which different queries can be directed based on their priority.
+
+## Query laning
+
+Query laning directs Druid to restrict resource usage for less urgent queries to ensure dedicated resources for higher priority queries. Query laning is ideal when you need to run many concurrent queries having heterogeneous workloads.

Review comment:
       The ideal solution to support heterogeneous workloads is the broker tiering today. Perhaps we should move this statement to the tiering section below?

##########
File path: docs/operations/query-concurrency.md
##########
@@ -0,0 +1,174 @@
+---
+id: query-concurrency
+title: Query concurrency

Review comment:
       I feel there could be a better title than this.. Would "Multi-workloads support" be better?

##########
File path: docs/operations/query-concurrency.md
##########
@@ -0,0 +1,174 @@
+---
+id: query-concurrency
+title: Query concurrency
+sidebar_label: Query concurrency
+---
+
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one
+  ~ or more contributor license agreements.  See the NOTICE file
+  ~ distributed with this work for additional information
+  ~ regarding copyright ownership.  The ASF licenses this file
+  ~ to you under the Apache License, Version 2.0 (the
+  ~ "License"); you may not use this file except in compliance
+  ~ with the License.  You may obtain a copy of the License at
+  ~
+  ~   http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing,
+  ~ software distributed under the License is distributed on an
+  ~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  ~ KIND, either express or implied.  See the License for the
+  ~ specific language governing permissions and limitations
+  ~ under the License.
+  -->
+
+If you frequently run concurrent, mixed workloads on your Druid cluster, configure Druid to properly allocate cluster resources and optimize your overall query performance. With proper resource isolation, you can execute long-running, low priority queries that are resource intensive without interfering with short-running, high priority queries that require fewer resources. By separating cluster resources, you prevent queries from competing with each other for resources such as CPU, memory, and network access.
+
+There are two approaches to isolate your resources for improving query concurrency: query laning and cluster tiering. Use query laning to set a limit on the maximum number of long-running queries executed on each Broker. Use cluster tiering to define separate groups of Historicals and Brokers to which different queries can be directed based on their priority.
+
+## Query laning
+
+Query laning directs Druid to restrict resource usage for less urgent queries to ensure dedicated resources for higher priority queries. Query laning is ideal when you need to run many concurrent queries having heterogeneous workloads.
+
+Query lanes are analogous to carpool and normal lanes on the freeway. With query laning, Druid restricts low priority queries to low lanes and allows high priority queries to run wherever possible, whether in a high or low lane. In this way, higher priority queries may bypass other queries in lower priority lanes.
+
+In Druid, query lanes reserve resources for Broker HTTP threads. Each Druid query requires one Broker thread. The number of threads on a Broker is defined by the `druid.server.http.numThreads` parameter. Broker threads may be occupied by tasks other than queries, such as health checks. You can use query laning to limit the number of HTTP threads designated for resource-intensive queries, leaving other threads available for short-running queries and other tasks.
+
+### General properties
+
+Set the following query laning properties in the `broker/runtime.properties` file.
+
+* `druid.query.scheduler.numThreads` – The total number of queries that can be served per Broker. We recommend setting this value to 1-2 less than `druid.server.http.numThreads`.

Review comment:
       Should this property appear after `laning.strategy` because it's optional?




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