Wangda Tan and Mayank Bansal presented on YARN Node Labels. Node labels allow grouping nodes with similar hardware or software profiles and partitioning a cluster. This allows applications to request nodes with specific resources and partitions the cluster for different organizations or workloads. Node partitions were added in Hadoop 2.6 to allow exclusive or non-exclusive access to labeled nodes. Ebay and other companies use node labels to separate machine learning, licensed software, and organizational workloads. Future work includes adding node constraints and supporting node labels in other Apache projects like FairScheduler, Tez and Oozie.

1. YARN Node Labels
Wangda Tan, Hortonorks (wangda@apache.org)
Mayank Bansal, ebay (mabansal@ebay.com)

2. About us
Wangda Tan
• Last 5+ years in big data field, Hadoop,
Open-MPI, etc.
• Now
• Apache Hadoop Committer
@Hortonworks, all in YARN.
• Now spending most of time on
resource scheduling enhancements.
• Past
• Pivotal (PHD team, brings
OpenMPI/GraphLab to YARN)
• Alibaba (ODPS team, platform for
distributed data-mining)
Mayank Bansal
• Hadoop Architect @ ebay
• Apache Hadoop Committer
• Apache Oozie PMC and Committer
• Current
• Leading Hadoop Core Development
for YARN and MapReduce @ ebay
• Past
• Working on Scheduler / Resource
Managers

3. Agenda
• Overview
• Problems
• What is node label
• Understand by example
• Architecture
• Case study
• Status
• Future

4. Overview – Background
• Resources are managed
by a hierarchy of queues.
• One queue can have
multiple applications
• Container is the result
resource scheduling,
Which is a bundle of
resources and can run
process(es)

5. Overview – How to manage your workload by queues
• By organization:
• Marketing/Finance queue
• By workload
• Interactive/Batch queue
• Hybrid
• Finance-
batch/Marketing-realtime
queue

6. Problems
• No way to specify for specific resource on nodes
• E.g. nodes with GPU / SSD
• No way for application to request nodes with specific resources.
• Unable to partition a cluster based on organizations/workloads

7. What is Node Label?
• Group nodes with similar profile
• Hardware
• Software
• Organization
• Workloads
• A way for app to specify where to run in a cluster

8. Node Labels
• Types of node labels
• Node partition (Since 2.6)
• Node constraints (WIP)
• Node partition
• One node belongs to only one partition
• Related to resource planning
• Node constraints
• One node can assign multiple
constraints
• Not related to resource planning

9. Understand by example (1)
• A real-world example about why node
partition is needed:
• Company-X has a big cluster, Each of
Engineering/Marketing/Sales team has
33% share of the cluster.
...
...
YARN RM
Engineer
33%
Marketing
33%
Sales
33%

10. Understand by example (2)
Engineer
50%
Marketing
50%
..
.
..
.
• Engineering/marketing team need GPU installed
servers to do some visualization works. So they spent
equal amount of money buy some machines with GPU.
• They want to share the cluster 50:50.
• Sales team spent $0 on these node nodes, so it cannot
run anything on these new nodes at all.

11. Understand by example (3)
• Here problem comes:
• if you create a separated YARN cluster, ops
team will unhappy.
• If you add these new nodes to original
cluster, you cannot guarantee
engineering/marking team have preference
to use these new nodes.
...
...
YARN RM
...
...
?

12. Understand by example (4)
...
...
YARN RM
...
...
"Default" Partition "GPU" Partition
Engineer
33%
Marketing
33%
Sales
33%
Engineer
50%
Marketing
50%
• Node partition is to solve this problem:
• Add GPU partition, which is managed by the same YARN RM. Admin can specify
different percentage of shares in different partitions.

13. Understand by example (5)
• Understand Non-exclusive node
partition:
• In the previous example, “GPU”
partition can be only used by
engineering and marketing team.
• This is a bad for resource utilization.
• Admin can define, if “GPU” partition
has idle resources, sales queue can use
it. But when engineering/marketing
come back. Resource allocated to sales
queue will be preempted.
• (available since Hadoop 2.8)
...
...
"Default" Partition
...
...
"GPU" Partition
Guaranteed to use Can use if it's idle
Engineer Marketing Sales
33%
33%
33%
50%
50%
0%

14. Understand by example (6)
• Configuration for above example (Capacity Scheduler)
yarn.scheduler.capacity.root.queues=engineering,marketing,sales
yarn.scheduler.capacity.root.engineering.capacity=33
yarn.scheduler.capacity.root.marketing.capacity=33
yarn.scheduler.capacity.root.sales.capacity=33
---------
yarn.scheduler.capacity.root.engineering.accessible-node-labels=GPU
yarn.scheduler.capacity.root.marketing.accessible-node-labels=GPU
---------
yarn.scheduler.capacity.root.engineering.accessible-node-labels.GPU.capacity=50
yarn.scheduler.capacity.root.marketing.accessible-node-labels.GPU.capacity=50
---------
(optional)
yarn.scheduler.capacity.root.engineering.default-node-label-expression=GPU
They’re original configuration
without node partition
Capacities
For node partitions.
Queue ACLs
For node partitions.
(optional)
Applications running in the queue
Will run in GPU partition
By default

15. Understand by example (7)
...
...
YARN RM
Company (100%)
R & D (50%) Sales (50%)
QE (20%) Dev (80%)
Without node partition
YARN RM
Company (100%)
R & D (50%) Sales (50%)
QE (20%) Dev (80%)
With node partition
Default GPU
Company (100%)
R & D (100%) Sales (0%)
QE (50%) Dev (50%)

16. Architecture
• Central piece:
NodeLabelsManager
• Stores labels and their attributes
• Store nodes-to-labels mapping
• It can be read/write by
• CLI and REST API (which we
called centralized configuration)
• OR NM can retrieve labels on it
and send to RM (we call it
distributed configuration)
• Scheduler uses node labels
manager make decisions and
receive resource request from
AM, return allocated
container to AM

17. Case study (1) – uses node label
• Use node label to create isolated
environment for
batch/interactive/low-latency
workloads.
• Deploy YARN containers onto
compute nodes are optimized and
accelerated for each workload:
• Using RDMA-enabled nodes to
accelerate shuffle.
• Using powerful CPU nodes to
accelerate compression.
• It is possible to DOUBLE THE
DENSITY of today’s traditional
Hadoop cluster with substantially
better price performance.
• Create a converged system that
allow Hadoop / Vertica / Spark and
other stacks share a common pool
of data.

18. Case study (2) – uses node label

19. Case study (3) – Ebay cluster use node label
• Separate Machine Learning workloads from regular workloads
• Use node label to separate licensed software to some machines
• Enabling GPU workloads
• Separation of organizational workloads

20. Case study (4) – Slider use cases
• HBase region servers run in nodes with
SSD (Non-exclusive).
• HBase master monopolize to use
nodes.
• Map-reduce jobs run in other nodes.
And they can use idle resources of
region server nodes.
... ...
HBase
Master
(Exclusive)
HBase
Region Server
(Non-Exclusive)
Default
Slider
HBase
Master RS RS
Launches
MR
AM
User
Submit
Task
Task
TaskTask

21. Status – Done parts of Node Labels
• Exclusive / non-exclusive node partition support in Capacity Scheduler (√)
• User-limit
• Preemption
• Now all respecting node partition!
• Centralized configuration via CLI/REST API (√)
• Distributed configuration in Node Manager’s config/script (√)

22. Status - Node Labels Web UI

23. Status – Other Apache projects support node label
• Following projects are already
support node label:
• (SPARK-6470)
• (MAPREDUCE-6304)
• Slider (SLIDER-81)
• (via SLIDER)
• (via SLIDER)
• (via SLIDER)
• (AMBARI-10063)

24. Future of Node Label
• Support constraints (YARN-3409)
• Orthogonal to partition, they’re
describing attributes of node’s
hardware/software just for
affinity.
• Some example of constraints:
• glibc version
• JDK version
• Type of CPU (x86_64/i686)
• Physical or virtualized
• With this, application can ask for
resource
• glibc.version >= 2.20 &&
JDK.version >= 8u20 &&
x86_64
• Support node label in
FairScheduler (YARN-2497)
• Support in more projects
• Tez
• Oozie
• …

25. Q & A