The document discusses extending the Starfish system to optimize multi-job workflows, iterative workflows, and key-value stores like HBase. It describes applying Starfish's profiling and optimization capabilities to the Cascading workflow system and supporting iterative MapReduce jobs. Optimizing the Alidade geolocation application is used as a case study.

1. Fei Dong
Duke University
April 6, 2012

2. • Introduction
• Optimizing Multi-Job Workflows
• Optimizing Iterative Workflows
• Optimizing Key-Value Stores
• Alidade: A Real-Life Application
• Summary
• Questions and Answers
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4. Typical Hadoop Stack New Software and Model
Oozie Sqoop Jaql
High Level MapReduce Hadoop Streaming
Programs(Java) (Python, Ruby) Pig Hive Cascading
Hadoop Core
Iterative
MapReduce Execution Engine EMR MRv2
Model
Distributed File System HBase ElephantDB
Physical Level Physical Machine Virtual Machine
SATA EC2
CPU SSD
Disk Unit
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5. Optimizers
Search through space of tuning choices
Cluster
Job
Data layout
Profiler What-if Engine
Workflow
Collects concise Workload Estimates impact of
summaries of hypothetical changes
execution on execution
Starfish limitation: focus on individual MapReduce jobs on Hadoop
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6. Starfish-Extended
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7. High-level layers have evolved over Hadoop to support
comprehensive workflows, such as Pig, Hive, Cascading.
Can we optimize such workflows with Starfish?
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8. • Data is processed iteratively.
• MapReduce framework does not directly support
iterations.
Loop: n
Input
Output3
/Input2
Output1 Output2
J1 J2 J3
/Input2 /Input3
Output J4
Can we support iterative execution in a workflow?
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9. • HDFS: Replication, Fault tolerance, Scalability
• HBase: Host very large tables – billions of rows
X millions of columns.
Can we optimize storage system like HBase?
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10. • Rule Based Optimization (RBO)
– Use a set of rules to determine how to execute a
plan.
• Cost Based Optimization
– Cheapest plan use the least amount of resource.
• Starfish employ CBO approach to MapReduce
programs.
Can we put RBO + CBO together ?
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11. 1. MapReduce Workflow Optimizer in Cascading
2. Iterative Workflow Optimizer
3. Key-Value Stores Optimizer using Rule-based
technology
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12. • Cascading
– Data processing API on Hadoop
– Flow of operation, not jobs
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13. • Replace Hadoop Old API with New API
• Cascading Profiler
– Job Graph + Conf Graph to represent a workflow
• Cascading What-if Engine
• Cascading Optimizer
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16. • The jobs have the same execution behavior
across iterations → we can use a single
“iterative” profile.
• Combine MapReduce jobs into a logical unit of
work (inspired by Oozie)
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17. • PageRank: 10G page graphs
3500
3000
Running Time (s)
2500
2000
1500 Original
1000 Optimization
500
0
1 2 4 6 10
Total Iteration
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18. 5. HBase Process e.g. splits, compactions
High
4. HBase Schema e.g. compression, bloom filter
3. HBase Configuration e.g. garbage collection, heap
2. Hadoop Configuration e.g. xciever, handlers
Low 1. Operating System e.g. ulimit, nproc
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19. • JVM Settings:
– "-server -XX:+UseParallelGC -XX:ParallelGCThraed=8 -
XX:+AggressivHeap -XX:+HeapDumpOnOutOfMemoryError".
– The parallel GC leverages multiple CPUs.
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23. • Recommend c1.xlarge, m2.xlarge to run HBase.
• Isolate HBase cluster to avoid memory competition with other
services.
• Factors to affect writing: HLog > Split> Compact.
• If applications do not require strict data durability, closing
HLog can get 2X speedup.
• Compression can save space on storage. Snappy provide high
speeds and reasonable compression.
• In a read-busy system, using bloom filters with the matching
update or read patterns can save a huge amount of IO.
• …
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24. • Alidade is constraint-based geolocation
system.
• Alidade has two phases.
– Preprocessing data
– Iterative geolocation
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26. 1. Iterative Model
2. Heavy Computation
– Represent polygon in a spherical surface.
– Calculate Intersection of polygons
3. Large Scale Data
4. Limited Resource Allocation
– Depend on many services such as
HDFS, JobTrackers, TaskTracker, HBase, etc.
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27. • Hadoop CDH3U3 based on 0.20.2
• HBase CDH3U3 based on 0.90.4
• 11 m1.large nodes, 11 m2.xlarge nodes
• 30 map slots and 20 reduce slots
• Workflow:
– YCSB generates 10M records and some workloads
on read/write.
– Alidade generates 70M records after translating.
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32. 11 m1.large 21 m1.large 11 m2.xlarge
Write Capacity 43593/s 87012/s 58273/s
CPU 44 88 72
Storage Capacity 8.5T 17T 17T
Nodes cost per hour $3.5 $7.1 $5.0
Traffic Cost $4 $8 $4
Setup Duration 2hr 2hr 2hr
AWS Billed Duration 19hr 11hr 12hr
Total Cost $68.6 $82.8 $68.8
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33. • Alidade is a CPU-intensive job. The
“IntersectionWritable.solve” contributes most
of executing time (> 70%).
• Currently, Starfish Optimizer is better fitted for
I/O intensive jobs
• Alidade helped Starfish improve Profiling.
(reduce overhead for “sequencefiles”)
• Memory issue for HBase
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34. • Extended Starfish to support the evolving
Hadoop system
– Automatic tuning of Cascading workflow. We can
boost performance by 20% to 200%.
– Support iterative workflow using simple syntax.
– Optimize Key-Value Stores in Hadoop
– Leveraged cost-based optimizer and rule-base
optimizer to get good performance in a complex
real-life workflow.
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36. Thanks

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