An introduction to Hoya, a prototype YARN application for deploying HBase in a YARN, using YARN to allocate space on nodes for the processes. The Hoya Application Master monitors the health of the Region Servers and, whenever one exits or whose host drops out of the cluster, requests a new YARN container and deploys a new instance. Hoya also supports live cluster flexing: increasing and decreasing cluster size dynamically. The source code is at https://github.com/hortonworks/hoya

1. © Hortonworks Inc. 2013
Hoya: HBase on YARN
Steve Loughran & Devaraj Das
{stevel, ddas} at hortonworks.com
@steveloughran, @ddraj
August 2013

2. © Hortonworks Inc. 2012
Hadoop as Next-Gen Platform
HADOOP 1.0
HDFS
(redundant, reliable storage)
MapReduce
(cluster resource management
& data processing)
HDFS2
(redundant, reliable storage)
YARN
(cluster resource management)
MapReduce
(data processing)
Others
(data processing)
HADOOP 2.0
Single Use System
Batch Apps
Multi Purpose Platform
Batch, Interactive, Online, Streaming, …
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3. © Hortonworks Inc.
YARN: Taking Hadoop Beyond Batch
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Applications Run Natively IN Hadoop
HDFS2 (Redundant, Reliable Storage)
YARN (Cluster Resource Management)
BATCH
(MapReduce)
INTERACTIVE
(Tez)
STREAMING
(Storm, S4,…)
GRAPH
(Giraph)
HPC MPI
(OpenMPI)
OTHER
(Search)
(Weave…)
Samza
Store ALL DATA in one place…
Interact with that data in MULTIPLE WAYS
with Predictable Performance and Quality of Service
IN-MEMORY
(Spark)

4. HDFS2 (Redundant, Reliable Storage)
YARN (Cluster Resource Management)
BATCH
(MapReduce)
INTERACTIVE
(Tez)
STREAMING
(Storm, S4,…)
GRAPH
(Giraph)
HPC MPI
(OpenMPI)
OTHER
(Search)
(Weave…)
HBase
IN-MEMORY
(Spark)
HDFS2 (Redundant, Reliable Storage)
YARN (Cluster Resource Management)
BATCH
(MapReduce)
INTERACTIVE
(Tez)
STREAMING
(Storm, S4,…)
GRAPH
(Giraph)
HPC MPI
(OpenMPI)
OTHER
(Search)
(Weave…)
HBase
IN-MEMORY
(Spark)
And HBase?

5. © Hortonworks Inc.
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6. © Hortonworks Inc.
Hoya: On-demand HBase clusters
1. Small HBase cluster in large YARN cluster
2. Dynamic HBase clusters
3. Elastic HBase clusters
4. Transient/intermittent clusters for workflows
5. Custom versions & configurations
6. More efficient utilization/sharing of cluster
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7. © Hortonworks Inc.
Goal: No code changes in HBase
• Today : none
HBase 0.95.2$ mvn install -Dhadoop.version=2.0
But we'd like
• ZK reporting of web UI ports
• Allocation of tables in RS to be block location aware
• A way to get from failed RS to YARN container
(configurable ID is enough)
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8. © Hortonworks Inc.
Hoya – the tool
• Hoya (Hbase On YArn)
–Java tool
–Completely CLI driven
• Input: cluster description as JSON
–Specification of cluster: node options, ZK params
–Configuration generated
–Entire state persisted
• Actions: create, freeze/thaw, flex, exists <cluster>
• Can change cluster state later
–Add/remove nodes, started / stopped states

9. © Hortonworks Inc. 2012
YARN manages the cluster
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HDFS
YARN Node Manager
HDFS
YARN Node Manager
HDFS
YARN Resource Manager
HDFS
YARN Node Manager
• Servers run YARN Node Managers
• NM's heartbeat to Resource Manager
• RM schedules work over cluster
• RM allocates containers to apps
• NMs start containers
• NMs report container health

10. © Hortonworks Inc. 2012
Hoya Client creates App Master
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HDFS
YARN Node Manager
HDFS
YARN Node Manager
HDFS
YARN Resource Manager
HDFS
YARN Node Manager
Hoya Client
Hoya AM

11. © Hortonworks Inc. 2012
AM deploys HBase with YARN
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HDFS
YARN Node Manager
HDFS
YARN Node Manager
HDFS
YARN Resource Manager
Hoya Client
HDFS
YARN Node Manager
Hoya AM [HBase Master]
HBase Region Server
HBase Region Server

12. © Hortonworks Inc. 2012
HBase & clients bind via Zookeeper
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HDFS
YARN Node Manager
HBase Region Server
HDFS
YARN Node Manager
HBase Region Server
HDFS
YARN Resource Manager
HBase Client HDFS
YARN Node Manager
Hoya AM [HBase Master]
Hoya Client

13. © Hortonworks Inc. 2012
YARN notifies AM of failures
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HDFS
YARN Node Manager
HDFS
YARN Node Manager
HBase Region Server
HDFS
YARN Resource Manager
Hoya Client
HDFS
YARN Node Manager
Hoya AM [HBase Master]
HBase Region Server
HBase Region Server

14. © Hortonworks Inc.
HOYA - cool bits
• Cluster specification stored as JSON in HDFS
• Conf dir cached, dynamically patched before pushing
up as local resources for master & region servers
• HBase .tar file stored in HDFS -clusters can use the
same/different HBase versions
• Handling of cluster flexing is the same code as
unplanned container loss.
• No Hoya code on region servers
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15. © Hortonworks Inc.
HOYA - AM RPC API
//shut down
public void stopCluster();
//change #of worker nodes in cluster
public boolean flexNodes(int workers);
//get JSON description of live cluster
public String getClusterStatus();
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16. © Hortonworks Inc.
Flexing/failure handling is same code
public boolean flexNodes(int workers) throws IOException {
log.info("Flexing cluster count from {} to {}", numTotalContainers,
workers);
if (numTotalContainers == workers) {
//no-op
log.info("Flex is a no-op");
return false;
}
//update the #of workers
numTotalContainers = workers;
// ask for more containers if needed
reviewRequestAndReleaseNodes();
return true;
}
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17. © Hortonworks Inc. 2012
{
"name" : "TestHBaseMaster",
"createTime" : 1371738651059,
"flags" : { "--Xtest" : "true" },
"originConfigurationPath" : "file:/Users/stevel/.hoya/cluster/TestHBaseMaster/orig",
"generatedConfigurationPath" :
"file:/Users/stevel/.hoya/cluster/TestHBaseMaster/gen",
"hBaseClientProperties" : { },
"hbaseHome" : "/Users/stevel/Java/Apps/hbase",
"hbaseRootPath" : "file:/Users/stevel/.hoya/cluster/TestHBaseMaster/hbase",
"zkHosts" : "127.0.0.1",
"zkPath" : "/hbase",
"zkPort" : 49564
"workers" : 5,
"masterHeap" : 128,
"masters" : 1,
"workerHeap" : 256,
"startTime" : 0,
"state" : 1,
"statusTime" : 0,
"stopTime" : 0,
}
Spec: declarative parts; this is persisted
Cluster Specification: persistent & wire

18. © Hortonworks Inc.
Current status
• Able to create & stop on-demand HBase clusters
–RegionServer failures handled
• Able to specify specific HBase configuration:
hbase-home or .tar.gz
• Cluster stop, restart, flex
• get (dynamic) conf as XML, properties

19. © Hortonworks Inc.
What's Next
• Multiple roles: worker, master, monitor
--role worker --roleopts worker yarn.vcores 2
• Multiple Providers: HBase + others
–client side: preflight, configuration patching
–server side: starting roles, liveness
• Liveness probes: HTTP GET, RPC port, RPC op?
• YARN enhancements
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20. © Hortonworks Inc.
YARN-896: long-lived services
1. Container reconnect on AM restart
2. Token renewal on long-lived apps
3. Containers: signalling, >1 process sequence
4. AM/RM managed gang scheduling
5. Anti-affinity hint in container requests
6. Service Registry - ZK?
7. Logging
All post Hadoop-2.1
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21. © Hortonworks Inc.
Hoya needs a home!
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https://github.com/hortonworks/hoya

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Questions?
hortonworks.com
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http://hortonworks.com/careers/
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P.S: we are hiring

24. © Hortonworks Inc.
Requirements of an App: MUST
• Install from tarball; run as normal user
• Pre-configurable, static instance config data
• deploy/start without human intervention
• support dynamic discovery/binding of peers
• co-existence with other app instance in cluster/nodes
• handle co-located role instances
• Persist data to HDFS
• support 'kill' as a shutdown option
• support role instances moving after failure
• handle failed role instances
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25. © Hortonworks Inc.
Requirements of an App: SHOULD
• Be configurable by Hadoop XML files
• Publish dynamically assigned web UI & RPC ports
• Support cluster flexing up/down
• Support API to determine role instance status
• Make it possible to determine role instance ID from
app
• Support simple remote liveness probes
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