Transcript Harp: Collective Communication on Hadoop Bingjing Zhang, Yang Ruan, Judy Qiu Outline • • • • • • Motivations – Why do we bring collective communications to big data processing? Collective.

Harp: Collective
Communication on Hadoop
Bingjing Zhang, Yang Ruan, Judy Qiu
Outline
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Motivations
– Why do we bring collective communications to big data processing?
Collective Communication Abstractions
– Our approach to optimize data movement
– Hierarchical data abstractions and operations defined on top of them
MapCollective Programming Model
– Extended from MapReduce model to support collective communications
– Two Level BSP parallelism
Harp Implementation
– A plugin on Hadoop
– Component layers and the job flow
Experiments
Conclusion
Motivation
More efficient and
much simpler!
K-means Clustering in
(Iterative) MapReduce
K-means Clustering in
Collective Communication
broadcast
M
M
M
M
M
shuffle
R
R
M
M
M
allreduce
gather
M: Compute local points sum
R: Compute global centroids
M: Control iterations and compute local
points sum
Large Scale Data Analysis Applications
• Iterative Applications
– Cached and reused local data between iterations
– Complicated computation steps
– Large intermediate data in communications
– Various communication patterns
Bioinformatics
Computer Vision Complex Networks
Deep Learning
The Models of Contemporary Big Data
Tools
DAG Model
MapReduce Model
Graph Model
BSP/Collective
Model
Hadoop
HaLoop
For
Iterations
/
Learning
Giraph
Hama
GraphLab
GraphX
Twister
Spark
Harp
Dryad
Stratosphere / Flink
For
Streaming
S4
Storm
DryadLINQ
For Query
Samza
Many of them have
fixed communication
patterns!
Spark Streaming
Pig
Hive
Tez
Spark SQL
MRQL
Contributions
Parallelism Model
Architecture
MapCollective Model
MapReduce Model
Application
M
M
M
MapCollective
Applications
M
M
Shuffle
R
MapReduce
Applications
M
M
M
Harp
Framework
Collective Communication
R
MapReduce V2
Resource
Manager
YARN
Collective Communication Abstractions
• Hierarchical Data Abstractions
– Basic Types
• Arrays, key-values, vertices, edges and messages
– Partitions
• Array partitions, key-value partitions, vertex partitions, edge partitions and
message partitions
– Tables
• Array tables, key-value tables, vertex tables, edge tables and message tables
• Collective Communication Operations
– Broadcast, allgather, allreduce
– Regroup
– Send messages to vertices, send edges to vertices
Hierarchical Data Abstractions
Table
Partition
Array Table
<Array Type>
Edge
Table
Array Partition
<Array Type>
Edge
Partition
broadcast, allgather, allreduce,
regroup, message-to-vertex…
Message
Vertex
Key-Value
Table
Table
Table
Message
Partition
Vertex
Partition
Key-Value
Partition
broadcast, send
Long
Array
Basic Types
Int
Array
Double
Array
Byte
Array
Array
Vertices, Edges,
Messages
Key-Values
Object
broadcast, send
Transferable
Example: regroup
Process 0
Process 1
Table
Table
Table
Partition 0
Partition 0
Partition 0
Partition 1
Partition 2
Partition 31
Partition 42
Partition 4
Partition 2
Partition 3
Regroup
Process 2
Operations
Operation Name
Data Abstraction
Algorithm
broadcast
arrays, key-value
pairs & vertices
chain
allgather
arrays, key-value
pairs & vertices
bucket
allreduce
arrays, key-value
pairs
bi-directional
exchange
Time Complexity
𝒏𝜷
𝒑𝒏𝜷
(𝒍𝒐𝒈𝟐 𝒑)𝒏𝜷
regroup-allgather
2𝒏𝜷
regroup
arrays, key-value
pairs & vertices
point-to-point
direct sending
𝒏𝜷
send messages
to vertices
messages,
vertices
point-to-point
direct sending
𝒏𝜷
send edges to
vertices
edges, vertices
point-to-point
direct sending
𝒏𝜷
MapCollective Programming Model
• BSP parallelism
– Inter node parallelism and inner node parallelism
Process
Level
Thread
Level
Process
Level
The Harp Library
• Hadoop Plugin which targets on Hadoop 2.2.0
• Provides implementation of the collective communication abstractions
and MapCollective programming model
• Project Link
– http://salsaproj.indiana.edu/harp/index.html
• Source Code Link
– https://github.com/jessezbj/harp-project
Component Layers
Applications: K-Means, WDA-SMACOF, Graph-Drawing…
MapReduce Applications
MapCollective Applications
MapCollective
Collective Communication Array, Key-Value, Graph
Interface
APIs
Data Abstraction
MapCollective Programming Model
Harp
Collective Communication
Hierarchical Data Types
Memory Resource
Operators
(Tables & Partitions)
Pool
MapReduce V2Abstractions
Collective Communication
Task Management
YARN
MapReduce
A MapCollective Job
YARN Resource Manager
I. Launch
AppMaster
Client
MapCollective
Runner
II. Launch
Tasks
MapCollective
AppMaster
MapCollective
Container
Allocator
MapCollective
Container
Launcher
1. Record Map task
locations from original
MapReduce AppMaster
CollectiveMapper
setup
mapCollective
2. Read key-value
pairs
3. Invoke collective
communication
APIs
cleanup
4. Write output to
HDFS
Experiments
• Applications
– K-means Clustering
– Force-directed Graph Drawing Algorithm
– WDA-SMACOF
• Test Environment
– Big Red II
• http://kb.iu.edu/data/bcqt.html
M
M
M
6000
140
5000
120
100
4000
80
3000
60
2000
40
1000
20
0
0
0
allreduce centroids
20
40
60
80
100
120
140
Number of Nodes
500M points 10K centroids Execution Time
5M points 1M centroids Execution Time
500M points 10K centroids Speedup
5M points 1M centroids Speedup
Speedup
M
Execution Time (Seconds)
K-means
Clustering
M
M
M
allgather positions of
vertices
8000
90
7000
80
6000
70
60
5000
50
4000
40
3000
Speedup
M
Execution Time (Seconds)
Force-directed
Graph Drawing
Algorithm
30
2000
20
1000
10
0
0
0
20
40
60
80 100
Number of Nodes
Execution Time
120
140
Speedup
T. Fruchterman, M. Reingold. “Graph Drawing by Force-Directed Placement”, Software Practice & Experience 21 (11), 1991.
Execution Time (seconds)
WDASMACOF
4000
3000
2000
1000
0
0
20
40
100K points
300K points
60
80
100 120
Number of Nodes
200K points
400K points
140
120
M
M
M
M
allgather and allreduce results in
the conjugate gradient process
allreduce the stress value
Speedup
100
80
60
40
20
0
0
20
100K points
40
60
80
100 120 140
Number of Nodes
200K points
300K points
Y. Ruan et al. “A Robust and Scalable Solution for Interpolative Multidimensional Scaling With Weighting”. E-Science, 2013.
Conclusions
• Harp is an implementation designed in a pluggable way to bring high
performance to the Apache Big Data Stack and bridge the differences
between Hadoop ecosystem and HPC system through a clear
communication abstraction, which did not exist before in the Hadoop
ecosystem.
• The experiments show that with Harp we can scale three applications
to 128 nodes with 4096 CPUs on the Big Red II supercomputer,
where the speedup in most tests is close to linear.