Apache Hadoop YARN: Past, Present and Future

1 © Hortonworks Inc. 2011 – 2016. All Rights Reserved
Apache Hadoop YARN:
Past, Present and
Future
Dublin, April 2016
Varun Vasudev

About myself
⬢ Apache Hadoop contributor since 2014
⬢ Apache Hadoop committer
⬢ Currently working for Hortonworks
⬢ vvasudev@apache.org

Introduction to Apache Hadoop YARN
YARN: Data Operating System
(Cluster Resource Management)
1 ° ° ° ° ° ° °
° ° ° ° ° ° ° °
Script
Pig
SQL
Hive
TezTez
Java
Scala
Cascading
Tez
° °
° °
° ° ° ° °
° ° ° ° °
Others
ISV
Engines
HDFS
(Hadoop Distributed File System)
Stream
Storm
Search
Solr
NoSQL
HBase
Accumulo
Slider Slider
BATCH, INTERACTIVE & REAL-TIME DATA ACCESS
In-Memory
Spark
YARN
The Architectural
Center of Hadoop
• Common data platform, many applications
• Support multi-tenant access & processing
• Batch, interactive & real-time use cases

Introduction to Apache Hadoop YARN
⬢ Architectural center of big data workloads
⬢ Enterprise adoption accelerating
–Secure mode becoming more widespread
–Multi-tenant support
–Diverse workloads
⬢ SLAs
–Tolerance for slow running jobs decreasing
–Consistent performance desired

5 © Hortonworks Inc. 2011 – 2016. All Rights Reserved5 © Hortonworks Inc. 2011 – 2016. All Rights Reserved
Past – Apache Hadoop 2.6, 2.7

Apache Hadoop YARN
ResourceManager
(active)
ResourceManager
(standby)
NodeManager1
NodeManager2
NodeManager3
NodeManager4
Resources: 128G, 16 vcores
Label: SAS

Scheduler
Inter queue pre-emption
Application
Queue B – 25%
Queue C – 25%
Label: SAS (exclusive)
Queue A – 50%
FIFO
ResourceManager
(active)
Application, Queue A, 4G, 1 vcore
Reservation for application
User

Node 1
NodeManager128G, 16 vcores
Launch Applicaton 1 AMAM process
Launch AM process via
ContainerExecutor – DCE, LCE, WSCE.
Monitor/isolate memory and cpu
Application Lifecycle
ResourceManager
(active)
Request containers
Allocate containers
Container 1 process
Container 2 process
Launch containers on node using
DCE, LCE, WSCE. Monitor/isolate
memory and cpu
History Server(ATS – leveldb,
JHS - HDFS)
HDFS
Log aggregation

Operational support
⬢ Support added for work preserving restarts in the RM and the NM
⬢ Support added for rolling upgrades and downgrades from 2.6 onwards

1
0
© Hortonworks Inc. 2011 – 2016. All Rights Reserved
Recent releases
⬢ 2.6 and 2.7 maintenance releases are carried out
–Only blockers and critical fixes are added
⬢ Apache Hadoop 2.7
–2.7.3 should be out soon
–2.7.2 released in January, 2016
–2.7.1 released in July, 2015
⬢ Apache Hadoop 2.6
–2.6.4 released in February, 2016
–2.6.3 released in December, 2015
–2.6.2 released in October, 2015

1
1
© Hortonworks Inc. 2011 – 2016. All Rights Reserved1
1
Present – Apache Hadoop 2.8

1
2
YARN
ResourceManager
(active)
ResourceManager
(standby)
NodeManager1
NodeManager2
NodeManager3
NodeManager4
Auto-calculate node resources
Label: SAS
Dynamic NodeManager
resource configuration

1
3
NodeManager resource management
⬢ Options to report NM resources based on node hardware
–YARN-160
–Restart of the NM required to enable feature
⬢ Alternatively, admins can use the rmadmin command to update the node’s resources
–YARN-291
–Looks at the dynamic-resource.xml
–No restart of the NM or the RM required

1
4
YARN Scheduler
Improvements to pre-emption
Application
Queue B – 25%
Queue C – 25%
Label: SAS (non-exclusive)
Queue A – 50%
Priority/FIFO, Fair
ResourceManager
(active)
Application, Queue A, 4G, 1 vcore
Support for application priority
Support for cost based placement
agent
User

1
5
Scheduler
⬢ Support for application priority within a queue
–YARN-1963
–Users can specify application priority
–Specified as an integer, higher number is higher priority
–Application priority can be updated while it’s running
⬢ Improvements to reservations
–YARN-2572
–Support for cost based placement agent added in addition to greedy
⬢ Queue allocation policy can be switched to fair sharing
–YARN-3319
–Containers allocated on a fair share basis instead of FIFO

1
6
Scheduler
⬢ Support for non-exclusive node labels
–YARN-3214
–Improvement over partition that existed earlier
–Better for cluster utilization
⬢ Improvements to pre-emption

1
7
Node 1
NodeManager
Support added for graceful
decomissioning
128G, 16 vcores
Launch Applicaton 1 AMAM process/Docker container(alpha)
Launch AM via ContainerExecutor –
DCE, LCE, WSCE. Monitor/isolate
memory and cpu. Support added for
disk and network isolation via
CGroups(alpha)
ResourceManager
(active)
Request containers
Allocate containers
Support added to resize containers. Container 1 process/Docker
container(alpha)
Container 2 process/Docker
container(alpha)
Launch containers on node using DCE,
LCE, WSCE. Monitor/isolate memory and
cpu. Support added for disk and network
isolation using Cgroups(alpha).
History Server(ATS 1.5– leveldb
+ HDFS, JHS - HDFS)
HDFS
Log aggregation

1
8
⬢ Graceful decommissioning of NodeManagers
–YARN-914
–Drains a node that’s being decommissioned to allow running containers to finish
⬢ Resource isolation support for disk and network
–YARN-2619, YARN-2140
–Containers get a fair share of disk and network resources using CGroups
–Alpha feature
⬢ Docker support in LinuxContainerExecutor
–YARN-3853
–Support to launch Docker containers alongside process containers
–Alpha feature
–Talk by Sidharta Seethana at 12:20 tomorrow in Liffey A

1
9
⬢ Support for container resizing
–YARN-1197
–Allows applications to change the size of an existing container
⬢ ATS 1.5
–YARN-4233
–Store timeline events on HDFS
–Better scalability and reliability

2
0
Operational support
⬢ Improvements to existing tools(like yarn logs)
⬢ New tools added(yarn top)
⬢ Improvements to the RM UI to expose more details about running applications

2
1
1
Future

2
2
Drivers for changes
⬢ Changing workload types
–Workloads have moved from batch to batch + interactive
–Workloads will change to batch + interactive + services
⬢ Big data workloads continue to evolve
–Spark on YARN the most popular way to run Spark in production
⬢ Containerization has taken off
–Docker becoming extremely popular
⬢ Improve ease of operations
–Easier to debug application failures/poor performance
–Make overall cluster management easier
–Improve existing tools such as yarn logs, yarn top, etc

2
3
Apache Hadoop YARN
ResourceManager
(active)
ResourceManager
(standby)
NodeManager1
NodeManager2
NodeManager3
NodeManager4
Add support for arbitrary resource types
Label: SAS
Add support for
federation – allow YARN
to scale
New RM UI

2
4
Future work
⬢ Support for arbitrary resource types and resource profiles
–YARN-3926
–Admins can add arbitrary resource types for scheduling
–Users can specify resource profile name instead of individual resources
⬢ YARN federation
–YARN-2915
–Allows YARN to scale out to tens of thousands of nodes
–Cluster of clusters which appear as a single cluster to an end user
⬢ New RM UI
–YARN-3368
–Enhanced usability
–Easier to add new features

2
5
Scheduler
Support for intra queue pre-emption
Application
Queue B – 25%
Queue C – 25%
Label: SAS (non-exclusive)
Queue A – 50%
Priority/FIFO, Fair
ResourceManager
(active)
Application, Queue A
Add support for resource profiles
User
New scheduler API
Schedule based on actual resource usage

2
6
Future work
⬢ New scheduler features
–YARN-4902
–Support richer placement strategies such as affinity, anti-affinity
⬢ Support pre-emption within a queue
–YARN-4781
⬢ More improvements to pre-emption
–YARN-4108, YARN-4390
⬢ Scheduling based on actual resource usage
–YARN-1011
–Nodes report actual memory and cpu usage to the scheduler to make better decisions

2
7
Node 1
NodeManager
Add distributed scheduling
128G, 16 vcores
Launch Applicaton 1 AMAM process/Docker container
Launch AM process via
ContainerExecutor – DCE, LCE, WSCE.
Monitor/isolate memory and cpu.
Support for disk and network isolation
ResourceManager
(active)
Request containers
Allocate containers
New scheduler API to allow far more
powerful placement strategies
container. Support container restart.
container. Support container restart.
Launch containers on node using DCE,
LCE, WSCE. Monitor/isolate memory and
cpu. Support for disk and network
isolation.
History Server(ATS v2 - HBase,
JHS - HDFS)
HDFS
Log aggregation
DNS sevice

2
8
Future work
⬢ Distributed scheduling
–YARN-2877, YARN-4742
–NMs run a local scheduler
–Allows faster scheduling turnaround
⬢ Better support for disk and network isolation
–Tied to supporting arbitrary resource types
⬢ Enhance Docker support
–YARN-3611
–Support to mount volumes
–Isolate containers using CGroups

2
9
Future work – support for services
⬢ YARN-4692
⬢ Container restart
–YARN-3988
–Allow container restart without losing allocation
⬢ Service discovery via DNS
–YARN-4757
–Running services can be discovered via DNS
⬢ Allocation re-use
–YARN-4726
–Allow AMs to stop a container but not lose resources on the node
–Required for application upgrades

3
0
Future work
⬢ ATS v2
–YARN-2928
–Run timeline service on Hbase
–Support for more data, better performance
⬢ Also in the pipeline
–Switch to Java 8 with Hadoop 3.0
–Add support for GPU isolation
–Better tools to detect limping nodes

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Thank you!

Apache Hadoop YARN: Past, Present and Future

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