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MAPREDUCE-3134. Added documentation the CapacityScheduler. 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1178530 13f79535-47bb-0310-9956-ffa450edef68
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Arun Murthy 2011-10-03 19:35:41 +00:00
parent 4ee39ffe6a
commit 43b59b894b
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hadoop-mapreduce-project/CHANGES.txt
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@ -333,6 +333,8 @@ Release 0.23.0 - Unreleased
MAPREDUCE-2889. Added documentation for writing new YARN applications.
(Hitesh Shah via acmurthy)
MAPREDUCE-3134. Added documentation the CapacityScheduler. (acmurthy)
OPTIMIZATIONS
MAPREDUCE-2026. Make JobTracker.getJobCounters() and

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hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/resources/capacity-scheduler.xml
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@ -3,76 +3,92 @@
<property>
<name>yarn.scheduler.capacity.maximum-applications</name>
<value>10000</value>
<description>Maximum number of applications that can be running.
<description>
Maximum number of applications that can be pending and running.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.maximum-am-resource-percent</name>
<value>0.1</value>
<description>
Maximum percent of resources in the cluster which can be used to run
application masters i.e. controls number of concurrent running
applications.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.queues</name>
<value>default</value>
<description>The queues at the this level (root is the root queue).
<description>
The queues at the this level (root is the root queue).
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.capacity</name>
<value>100</value>
<description>The total capacity as a percentage out of 100 for this queue.
If it has child queues then this includes their capacity as well.
The child queues capacity should add up to their parent queue's capacity
or less.</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.acl_administer_queues</name>
<value>*</value>
<description>The ACL for who can administer this queue. i.e.
change sub queue allocations.</description>
<description>
The total capacity as a percentage out of 100 for this queue.
If it has child queues then this includes their capacity as well.
The child queues capacity should add up to their parent queue's capacity
or less.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.capacity</name>
<value>100</value>
<description>default queue target capacity.</description>
<description>Default queue target capacity.</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.user-limit-factor</name>
<value>1</value>
<description>default queue user limit a percantage from 0.0 to 1.0.
<description>
Default queue user limit a percentage from 0.0 to 1.0.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.maximum-capacity</name>
<value>-1</value>
<description>the maximum capacity of the default queue -1 disables.
<description>
The maximum capacity of the default queue. A value of -1 disables this.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.state</name>
<value>RUNNING</value>
<description>The state of the default queue. can be RUNNING or STOPPED
<description>
The state of the default queue. State can be one of RUNNING or STOPPED.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.acl_submit_jobs</name>
<value>*</value>
<description>The ACL of who can submit jobs to the default queue.
<description>
The ACL of who can submit jobs to the default queue.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.default.acl_administer_jobs</name>
<value>*</value>
<description>The ACL of who can administer jobs on the default queue.
<description>
The ACL of who can administer jobs on the default queue.
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.acl_administer_queues</name>
<value>*</value>
<description>
The ACL for who can administer this queue i.e. change sub-queue
allocations.
</description>
</property>

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hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/CapacityScheduler.apt.vm Normal file
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@ -0,0 +1,309 @@
~~ Licensed 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. See accompanying LICENSE file.
---
Hadoop Map Reduce Next Generation-${project.version} - Capacity Scheduler
---
---
${maven.build.timestamp}
Hadoop MapReduce Next Generation - Capacity Scheduler
\[ {{{./index.html}Go Back}} \]
%{toc|section=1|fromDepth=0}
* {Purpose}
This document describes the <<<CapacityScheduler>>>, a pluggable scheduler
for Hadoop which allows for multiple-tenants to securely share a large cluster
such that their applications are allocated resources in a timely manner under
constraints of allocated capacities.
* {Overview}
The <<<CapacityScheduler>>> is designed to run Hadoop applications as a
shared, multi-tenant cluster in an operator-friendly manner while maximizing
the throughput and the utilization of the cluster.
Traditionally each organization has it own private set of compute resources
that have sufficient capacity to meet the organization's SLA under peak or
near peak conditions. This generally leads to poor average utilization and
overhead of managing multiple independent clusters, one per each organization.
Sharing clusters between organizations is a cost-effective manner of running
large Hadoop installations since this allows them to reap benefits of
economies of scale without creating private clusters. However, organizations
are concerned about sharing a cluster because they are worried about others
using the resources that are critical for their SLAs.
The <<<CapacityScheduler>>> is designed to allow sharing a large cluster while
giving each organization capacity guarantees. The central idea is
that the available resources in the Hadoop cluster are shared among multiple
organizations who collectively fund the cluster based on their computing
needs. There is an added benefit that an organization can access
any excess capacity no being used by others. This provides elasticity for
the organizations in a cost-effective manner.
Sharing clusters across organizations necessitates strong support for
multi-tenancy since each organization must be guaranteed capacity and
safe-guards to ensure the shared cluster is impervious to single rouge
application or user or sets thereof. The <<<CapacityScheduler>>> provides a
stringent set of limits to ensure that a single application or user or queue
cannot consume dispropotionate amount of resources in the cluster. Also, the
<<<CapacityScheduler>>> provides limits on initialized/pending applications
from a single user and queue to ensure fairness and stability of the cluster.
The primary abstraction provided by the <<<CapacityScheduler>>> is the concept
of <queues>. These queues are typically setup by administrators to reflect the
economics of the shared cluster.
To provide further control and predictability on sharing of resources, the
<<<CapacityScheduler>>> supports <heirarchical queues> to ensure
resources are shared among the sub-queues of an organization before other
queues are allowed to use free resources, there-by providing <affinity>
for sharing free resources among applications of a given organization.
* {Features}
The <<<CapacityScheduler>>> supports the following features:
* Heirarchical Queues - Heirarchy of queues is supported to ensure resources
are shared among the sub-queues of an organization before other
queues are allowed to use free resources, there-by providing more control
and predictability.
* Capacity Guarantees - Queues are allocated a fraction of the capacity of the
grid in the sense that a certain capacity of resources will be at their
disposal. All applications submitted to a queue will have access to the
capacity allocated to the queue. Adminstrators can configure soft limits and
optional hard limits on the capacity allocated to each queue.
* Security - Each queue has strict ACLs which controls which users can submit
applications to individual queues. Also, there are safe-guards to ensure
that users cannot view and/or modify applications from other users.
Also, per-queue and system administrator roles are supported.
* Elasticity - Free resources can be allocated to any queue beyond it's
capacity. When there is demand for these resources from queues running below
capacity at a future point in time, as tasks scheduled on these resources
complete, they will be assigned to applications on queues running below the
capacity. This ensures that resources are available in a predictable and
elastic manner to queues, thus preventing artifical silos of resources in
the cluster which helps utilization.
* Multi-tenancy - Comprehensive set of limits are provided to prevent a
single application, user and queue from monpolizing resources of the queue
or the cluster as a whole to ensure that the cluster isn't overwhelmed.
* Operability
* Runtime Configuration - The queue definitions and properties such as
capacity, ACLs can be changed, at runtime, by administrators in a secure
manner to minimize disruption to users. Also, a console is provided for
users and administrators to view current allocation of resources to
various queues in the system. Administrators can also
<add additional queues> at runtime.
* Drain applications - Administrators can <stop> queues
at runtime to ensure that while existing applications run to completion,
no new applications can be submitted. If a queue is in <<<STOPPED>>>
state, new applications cannot be submitted to <itself> or
<any of its child queueus>. Existing applications continue to completion,
thus the queue can be <drained> gracefully. Administrators can also
<start> the stopped queues.
* Resource-based Scheduling - Support for resource-intensive applications,
where-in a application can optionally specify higher resource-requirements
than the default, there-by accomodating applications with differing resource
requirements. Currently, <memory> is the the resource requirement supported.
[]
* {Configuration}
* Setting up <<<ResourceManager>>> to use <<<CapacityScheduler>>>
To configure the <<<ResourceManager>>> to use the <<<CapacityScheduler>>>, set
the following property in the <<conf/yarn-site.xml>>:
*--------------------------------------+--------------------------------------+
|| Property || Value |
*--------------------------------------+--------------------------------------+
| <<<yarn.resourcemanager.scheduler.class>>> | |
| | <<<org.apache.hadoop.yarn.server.resourcemanager.scheduler.fifo.CapacityScheduler>>> |
*--------------------------------------------+--------------------------------------------+
* Setting up <queues>
<<conf/capacity-scheduler.xml>> is the configuration file for the
<<<CapacityScheduler>>>.
The <<<CapacityScheduler>>> has a pre-defined queue called <root>. All
queueus in the system are children of the root queue.
Further queues can be setup by configuring
<<<yarn.scheduler.capacity.root.queues>>> with a list of comma-separated
child queues.
The configuration for <<<CapacityScheduler>>> uses a concept called
<queue path> to configure the heirarchy of queues. The <queue path> is the
full path of the queue's heirarcy, starting at <root>, with . (dot) as the
delimiter.
A given queue's children can be defined with the configuration knob:
<<<yarn.scheduler.capacity.<queue-path>.queues>>>
Here is an example with three top-level child-queues <<<a>>>, <<<b>>> and
<<<c>>> and some sub-queues for <<<a>>> and <<<b>>>:
----
<property>
<name>yarn.scheduler.capacity.root.queues</name>
<value>a,b,c</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.a.queues</name>
<value>a1,a2</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
<property>
<name>yarn.scheduler.capacity.root.b.queues</name>
<value>b1,b2,b3</value>
<description>The queues at the this level (root is the root queue).
</description>
</property>
----
* Queue Properties
* Resource Allocation
*--------------------------------------+--------------------------------------+
|| Property || Description |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.<queue-path>.capacity>>> | |
| | Queue <capacity> in percentage (%). |
| | The sum of capacities for all queues, at each level, should be less than |
| | or equal to 100. |
| | Applications in the queue may consume more resources than the queue's |
| | capacity if there are free resources, providing elasticity. |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.<queue-path>.maximum-capacity>>> | |
| | Maximum queue capacity in percentage (%). |
| | This limits the <elasticity> for applications in the queue. |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.<queue-path>.minimum-user-limit-percent>>> | |
| | Each queue enforces a limit on the percentage of resources allocated to a |
| | user at any given time, if there is demand for resources. The user limit |
| | can vary between a minimum and maximum value. The former depends on the |
| | number of users who have submitted applications, and the latter is set to |
| | this property value. For e.g., suppose the value of this property is 25. |
| | If two users have submitted applications to a queue, no single user can |
| | use more than 50% of the queue resources. If a third user submits an |
| | application, no single user can use more than 33% of the queue resources. |
| | With 4 or more users, no user can use more than 25% of the queues |
| | resources. A value of 100 implies no user limits are imposed. |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.<queue-path>.user-limit-factor>>> | |
| | The multiple of the queue capacity which can be configured to allow a |
| | single user to acquire more resources. By default this is set to 1 which |
| | ensures that a single user can never take more than the queue's configured |
| | capacity irrespective of how idle th cluster is. |
*--------------------------------------+--------------------------------------+
* Running and Pending Application Limits
The <<<CapacityScheduler>>> supports the following parameters to control
the runnign and pending applications:
*--------------------------------------+--------------------------------------+
|| Property || Description |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.maximum-applications>>> | |
| | Maximum number of jobs in the system which can be concurently active |
| | both running and pending. Limits on each queue are directly proportional |
| | to their queue capacities. |
*--------------------------------------+--------------------------------------+
| yarn.scheduler.capacity.maximum-am-resource-percent | |
| | Maximum percent of resources in the cluster which can be used to run |
| | application masters - controls number of concurrent running applications. |
*--------------------------------------+--------------------------------------+
* Queue Administration & Permissions
The <<<CapacityScheduler>>> supports the following parameters to
the administer the queues:
*--------------------------------------+--------------------------------------+
|| Property || Description |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.<queue-path>.state>>> | |
| | The <state> of the queue. Can be one of <<<RUNNING>>> or <<<STOPPED>>>. |
| | If a queue is in <<<STOPPED>>> state, new applications cannot be |
| | submitted to <itself> or <any of its child queueus>. |
| | Thus, if the <root> queue is <<<STOPPED>>> no applications can be |
| | submitted to the entire cluster. |
| | Existing applications continue to completion, thus the queue can be
| | <drained> gracefully. |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.root.<queue-path>.acl_submit_jobs>>> | |
| | The <ACL> which controls who can <submit> jobs to the given queue. |
| | If the given user/group has necessary ACLs on the given queue or |
| | <one of the parent queues in the hierarchy> they can submit jobs. |
*--------------------------------------+--------------------------------------+
| <<<yarn.scheduler.capacity.root.<queue-path>.acl_administer_jobs>>> | |
| | The <ACL> which controls who can <administer> jobs on the given queue. |
| | If the given user/group has necessary ACLs on the given queue or |
| | <one of the parent queues in the hierarchy> they can administer jobs. |
*--------------------------------------+--------------------------------------+
<Note:> An <ACL> is of the form <user1>, <user2><space><group1>, <group2>.
The special value of <<*>> implies <anyone>. The special value of <space>
implies <no one>.
* Reviewing the configuration of the CapacityScheduler
Once the installation and configuration is completed, you can review it
after starting the YARN cluster from the web-ui.
* Start the YARN cluster in the normal manner.
* Open the <<<ResourceManager>>> web UI.
* The </scheduler> web-page should show the resource usages of individual
queues.
[]
* {Changing Queue Configuration}
Changing queue properties and adding new queues is very simple. You need to
edit <<conf/capacity-scheduler.xml>> and run <rmadmin -refreshQueues>.
----
$ vi $HADOOP_CONF_DIR/capacity-scheduler.xml
$ $YARN_HOME/bin/rmadmin -refreshQueues
----
<Note:> Queues cannot be <deleted>, only addition of new queues is supported -
the updated queue configuration should be a valid one i.e. queue-capacity at
each <level> should be equal to 100%.

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@ -45,3 +45,5 @@ Hadoop MapReduce Next Generation
* {{{./WritingYarnApplications.html}Writing Yarn Applications}}
* {{{./CapacityScheduler.html}Capacity Scheduler}}