Helsinki Spark Meetup Nov 20, 2015: Spark After Dark 1.5: Real-time, Advanced Analytics with Spark 1.5, Kafka, Cassandra, ElasticSearch, Zeppelin, and Docker
Chris FreglyAI and Machine Learning @ AWS, O'Reilly Author @ Data Science on AWS, Founder @ PipelineAI, Formerly Databricks, Netflix,
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After Dark 1.5
High Performance, Real-time, Streaming,
Machine Learning, Natural Language Processing,
Text Analytics, and Recommendations
Chris Fregly
Principal Data Solutions Engineer
IBM Spark Technology Center
** We’re Hiring -- Only Nice People, Please!! **
November 20, 2015
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Who Am I?
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Streaming Data Engineer
Open Source Committer
Data Solutions Engineer
Apache Contributor
Principal Data Solutions Engineer
IBM Technology Center
Founder
Advanced Apache Meetup
Author
Advanced .
Due 2016
My Ma’s First Time in California
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Random Slide: More Ma “First Time” Pics
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In California
Using Chopsticks
Using “New” iPhone
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Upcoming Meetups and Conferences
London Spark Meetup (Oct 12th)
Scotland Data Science Meetup (Oct 13th)
Dublin Spark Meetup (Oct 15th)
Barcelona Spark Meetup (Oct 20th)
Madrid Big Data Meetup (Oct 22nd)
Paris Spark Meetup (Oct 26th)
Amsterdam Spark Summit (Oct 27th)
Brussels Spark Meetup (Oct 30th)
Zurich Big Data Meetup (Nov 2nd)
Geneva Spark Meetup (Nov 5th)
San Francisco Datapalooza.io (Nov 10th)
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San Francisco Advanced Spark (Nov 12th)
Oslo Big Data Hadoop Meetup (Nov 19th)
Helsinki Spark Meetup (Nov 20th)
Stockholm Spark Meetup (Nov 23rd)
Copenhagen Spark Meetup (Nov 25th)
Budapest Spark Meetup (Nov 26th)
Singapore Strata Conference (Dec 1st)
San Francisco Advanced Spark (Dec 8th)
Mountain View Advanced Spark (Dec 10th)
Toronto Spark Meetup (Dec 14th)
Austin Data Days Conference (Jan 2016)
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Advanced Apache Spark Meetup
Meetup Metrics
1600+ Members in just 4 mos!
Top 5 Most Active Spark Meetup!!
Meetup Goals
Dig deep into codebase of Spark and related projects
Study integrations of Cassandra, ElasticSearch,
Tachyon, S3, BlinkDB, Mesos, YARN, Kafka, R
Surface and share patterns and idioms of these
well-designed, distributed, big data components
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All Slides and Code Are Available!
advancedspark.com
slideshare.net/cfregly
github.com/fluxcapacitor
hub.docker.com/r/fluxcapacitor
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What is “
After Dark”?
Spark-based, Advanced Analytics Reference App
End-to-End, Scalable, Real-time Big Data Pipeline
Demonstration of Spark & Related Big Data Projects
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github.com/fluxcapacitor
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Tools of This Talk
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Kafka
Redis
Docker
Ganglia
Cassandra
Parquet, JSON, ORC, Avro
Apache Zeppelin Notebooks
Spark SQL, DataFrames, Hive
ElasticSearch, Logstash, Kibana
Spark ML, GraphX, Stanford CoreNLP
…
github.com/fluxcapacitor
hub.docker.com/r/fluxcapacitor
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Themes of this Talk
Filter
Off-Heap
Parallelize
Approximate
Find Similarity
Minimize Seeks
Maximize Scans
Customize for Workload
Tune Performance At Every Layer
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Be Nice, Collaborate!
Like a Mom!!
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Presentation Outline
Spark Core: Tuning & Mechanical Sympathy
Spark SQL: Query Optimizing & Catalyst
Spark Streaming: Scaling & Approximations
Spark ML: Featurizing & Recommendations
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Spark Core: Tuning & Mechanical Sympathy
Understand and Acknowledge Mechanical Sympathy
Study AlphaSort and 100Tb GraySort Challenge
Dive Deep into Project Tungsten
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Mechanical Sympathy
Hardware and software working together in harmony.
- Martin Thompson
http://mechanical-sympathy.blogspot.com
Whatever your data structure, my array will beat it.
- Scott Meyers
Every C++ Book, basically
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Hair
Sympathy
- Bruce Jenner
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Spark and Mechanical Sympathy
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Project
Tungsten
(Spark 1.4-1.6+)
GraySort
Challenge
(Spark 1.1-1.2)
Minimize Memory and GC
Maximize CPU Cache Locality
Saturate Network I/O
Saturate Disk I/O
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AlphaSort Technique: Sort 100 Bytes Recs
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Value
Ptr
Key
Dereference Not Required!
AlphaSort
List [(Key, Pointer)]
Key is directly available for comparison
Naïve
List [Pointer]
Must dereference key for comparison
Ptr
Dereference for Key Comparison
Key
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CPU Cache Line and Memory Sympathy
Key (10 bytes)+Pointer (*4 bytes)*Compressed OOPs
= 14 bytes
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Key
Ptr
Not CPU Cache-line Friendly!
Ptr
Key-Prefix
2x CPU Cache-line Friendly!
Key-Prefix (4 bytes) + Pointer (4 bytes)
= 8 bytes
Key (10 bytes)+Pad (2 bytes)+Pointer (4 bytes)
= 16 bytes
Key
Ptr
Pad
/Pad
CPU Cache-line Friendly!
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Performance Comparison
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Similar Trick: Direct Cache Access (DCA)
Pull out packet header along side pointer to payload
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CPU Cache Line Sizes
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My
Laptop
My
SoftLayer
BareMetal
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Cache Hits: Sequential v Random Access
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Mechanical Sympathy
CPU Cache Lines and Matrix Multiplication
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CPU Cache Naïve Matrix Multiplication
// Dot product of each row & column vector
for (i <- 0 until numRowA)
for (j <- 0 until numColsB)
for (k <- 0 until numColsA)
res[ i ][ j ] += matA[ i ][ k ] * matB[ k ][ j ];
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Bad: Row-wise traversal,
not using CPU cache line,
ineffective pre-fetching
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CPU Cache Friendly Matrix Multiplication
// Transpose B
for (i <- 0 until numRowsB)
for (j <- 0 until numColsB)
matBT[ i ][ j ] = matB[ j ][ i ];
// Modify dot product calculation for B Transpose
for (i <- 0 until numRowsA)
for (j <- 0 until numColsB)
for (k <- 0 until numColsA)
res[ i ][ j ] += matA[ i ][ k ] * matBT[ j ][ k ];
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Good: Full CPU cache line,
effective prefetching
OLD: res[ i ][ j ] += matA[ i ][ k ] * matB [ k ] [ j ];
Reference j
before k
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Instrumenting and Monitoring CPU
Use Linux perf command!
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http://www.brendangregg.com/blog/2015-11-06/java-mixed-mode-flame-graphs.html
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Demo!
Compare CPU Naïve & Cache-Friendly Matrix Multiplication
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Results of Matrix Multiply Comparison
Naïve Matrix Multiply
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Cache-Friendly Matrix Multiply
~27x
~13x
~13x
~2x
perf stat -XX:-Inline –event
L1-dcache-load-misses,L1-dcache-prefetch-misses,LLC-load-misses,
LLC-prefetch-misses,cache-misses,stalled-cycles-frontend
~10x
55 hp
550 hp
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Mechanical Sympathy
CPU Cache Lines and Lock-Free Thread Sync
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CPU Cache Naïve Tuple Counters
object CacheNaiveTupleIncrement {
var tuple = (0,0)
…
def increment(leftIncrement: Int, rightIncrement: Int) : (Int, Int) = {
this.synchronized {
tuple = (tuple._1 + leftIncrement, tuple._2 + rightIncrement)
tuple
}
}
}
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CPU Cache Naïve Case Class Counters
case class MyTuple(left: Int, right: Int)
object CacheNaiveCaseClassCounters {
var tuple = new MyTuple(0,0)
…
def increment(leftIncrement: Int, rightIncrement: Int) : MyTuple = {
this.synchronized {
tuple = new MyTuple(tuple.left + leftIncrement,
tuple.right + rightIncrement)
tuple
}
}
}
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CPU Cache Friendly Lock-Free Counters
object CacheFriendlyLockFreeCounters {
// a single Long (8-bytes) will maintain 2 separate Ints (4-bytes each)
val tuple = new AtomicLong()
…
def increment(leftIncrement: Int, rightIncrement: Int) : Long = {
var originalLong = 0L
var updatedLong = 0L
do {
originalLong = tuple.get()
val originalRightInt = originalLong.toInt // cast originalLong to Int to get right counter
val originalLeftInt = (originalLong >>> 32).toInt // shift right to get left counter
val updatedRightInt = originalRightInt + rightIncrement // increment right counter
val updatedLeftInt = originalLeftInt + leftIncrement // increment left counter
updatedLong = updatedLeftInt // update the new long with the left counter
updatedLong = updatedLong << 32 // shift the new long left
updatedLong += updatedRightInt // update the new long with the right counter
} while (tuple.compareAndSet(originalLong, updatedLong) == false)
updatedLong
}
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Q: Why not @volatile long?
A: Java Memory Model
does not guarantee synchronous
updates of 64-bit longs or doubles
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Demo!
Compare CPU Naïve & Cache-Friendly Tuple Counter Sync
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Results of Counters Comparison
Naïve Tuple Counters
Naïve Case Class Counters
Cache Friendly Lock-Free Counters
~2x
~1.5x
~3.5x
~2x
~2x
~1.5x
~1.5x
~1.5x
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Profiling Visualizations: Flame Graphs
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Example: Spark Word Count
Java Stack Traces
(-XX:+PreserveFramePointer)
Plateaus
are Bad!!
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100TB Daytona GraySort Challenge
Focus on Network and Disk I/O Optimizations
Improve Data Structs/Algos for Sort & Shuffle
Saturate Network and Disk Controllers
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Winning Results
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Spark Goals
Saturate Network I/O
Saturate Disk I/O
(2013) (2014)
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Winning Hardware Configuration
Compute
206 Workers, 1 Master (AWS EC2 i2.8xlarge)
32 Intel Xeon CPU E5-2670 @ 2.5 Ghz
244 GB RAM, 8 x 800GB SSD, RAID 0 striping, ext4
3 GBps mixed read/write disk I/O per node
Network
AWS Placement Groups, VPC, Enhanced Networking
Single Root I/O Virtualization (SR-IOV)
10 Gbps, low latency, low jitter (iperf: ~9.5 Gbps)
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Winning Software Configuration
Spark 1.2, OpenJDK 1.7
Disable caching, compression, spec execution, shuffle spill
Force NODE_LOCAL task scheduling for optimal data locality
HDFS 2.4.1 short-circuit local reads, 2x replication
Empirically chose between 4-6 partitions per cpu
206 nodes * 32 cores = 6592 cores
6592 cores * 4 = 26,368 partitions
6592 cores * 6 = 39,552 partitions
6592 cores * 4.25 = 28,000 partitions (empirical best)
Range partitioning takes advantage of sequential keyspace
Required ~10s of sampling 79 keys from in each partition
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New Sort Shuffle Manager for Spark 1.2
Original “hash-based”
New “sort-based”
① Use less OS resources (socket buffers, file descriptors)
② TimSort partitions in-memory
③ MergeSort partitions on-disk into a single master file
④ Serve partitions from master file: seek once, sequential scan
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Asynchronous Network Module
Switch to asyncronous Netty vs. synchronous java.nio
Switch to zero-copy epoll
Use only kernel-space between disk and network controllers
Custom memory management
spark.shuffle.blockTransferService=netty
Spark-Netty Performance Tuning
spark.shuffle.io.preferDirectBuffers=true
Reuse off-heap buffers
spark.shuffle.io.numConnectionsPerPeer=8 (for example)
Increase to saturate hosts with multiple disks (8x800 SSD)
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Details in
SPARK-2468
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Custom Algorithms and Data Structures
Optimized for sort & shuffle workloads
o.a.s.util.collection.TimSort[K,V]
Based on JDK 1.7 TimSort
Performs best with partially-sorted runs
Optimized for elements of (K,V) pairs
Sorts impl of SortDataFormat (ie. KVArraySortDataFormat)
o.a.s.util.collection.AppendOnlyMap
Open addressing hash, quadratic probing
Array of [(K, V), (K, V)]
Good memory locality
Keys never removed, values only append
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Daytona GraySort Challenge Goal Success
1.1 Gbps/node network I/O (Reducers)
Theoretical max = 1.25 Gbps for 10 GB ethernet
3 GBps/node disk I/O (Mappers)
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Aggregate
Cluster
Network I/O!
220 Gbps / 206 nodes ~= 1.1 Gbps per node
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Shuffle Performance Tuning Tips
Hash Shuffle Manager (Deprecated)
spark.shuffle.consolidateFiles (Mapper)
o.a.s.shuffle.FileShuffleBlockResolver
Intermediate Files
Increase spark.shuffle.file.buffer (Reducer)
Increase spark.reducer.maxSizeInFlight if memory allows
Use Smaller Number of Larger Executors
Minimizes intermediate files and overall shuffle
More opportunity for PROCESS_LOCAL
SQL: BroadcastHashJoin vs. ShuffledHashJoin
spark.sql.autoBroadcastJoinThreshold
Use DataFrame.explain(true) or EXPLAIN to verify
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Many Threads
(1 per CPU)
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Project Tungsten
Data Struts & Algos Operate Directly on Byte Arrays
Maximize CPU Cache Locality, Minimize GC
Utilize Dynamic Code Generation
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SPARK-7076
(Spark 1.4)
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Quick Review of Project Tungsten Jiras
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SPARK-7076
(Spark 1.4)
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Why is CPU the Bottleneck?
CPU is used for serialization, hashing, compression!
Network and Disk I/O bandwidth are relatively high
GraySort optimizations improved network & shuffle
Partitioning, pruning, and predicate pushdowns
Binary, compressed, columnar file formats (Parquet)
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Yet Another Spark Shuffle Manager!
spark.shuffle.manager =
hash (Deprecated)
< 10,000 reducers
Output partition file hashes the key of (K,V) pair
Mapper creates an output file per partition
Leads to M*P output files for all partitions
sort (GraySort Challenge)
> 10,000 reducers
Default from Spark 1.2-1.5
Mapper creates single output file for all partitions
Minimizes OS resources, netty + epoll optimizes network I/O, disk I/O, and memory
Uses custom data structures and algorithms for sort-shuffle workload
Wins Daytona GraySort Challenge
tungsten-sort (Project Tungsten)
Default since 1.5
Modification of existing sort-based shuffle
Uses com.misc.Unsafe for self-managed memory and garbage collection
Maximize CPU utilization and cache locality with AlphaSort-inspired binary data structures/algorithms
Perform joins, sorts, and other operators on both serialized and compressed byte buffers
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CPU & Memory Optimizations
Custom Managed Memory
Reduces GC overhead
Both on and off heap
Exact size calculations
Direct Binary Processing
Operate on serialized/compressed arrays
Kryo can reorder/sort serialized records
LZF can reorder/sort compressed records
More CPU Cache-aware Data Structs & Algorithms
o.a.s.sql.catalyst.expression.UnsafeRow
o.a.s.unsafe.map.BytesToBytesMap
Code Generation (default in 1.5)
Generate source code from overall query plan
100+ UDFs converted to use code generation
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UnsafeFixedWithAggregationMap
TungstenAggregationIterator
CodeGenerator
GeneratorUnsafeRowJoiner
UnsafeSortDataFormat
UnsafeShuffleSortDataFormat
PackedRecordPointer
UnsafeRow
UnsafeInMemorySorter
UnsafeExternalSorter
UnsafeShuffleWriter
Mostly Same Join Code,
UnsafeProjection
UnsafeShuffleManager
UnsafeShuffleInMemorySorter
UnsafeShuffleExternalSorter
Details in
SPARK-7075
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sun.misc.Unsafe
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Info
addressSize()
pageSize()
Objects
allocateInstance()
objectFieldOffset()
Classes
staticFieldOffset()
defineClass()
defineAnonymousClass()
ensureClassInitialized()
Synchronization
monitorEnter()
tryMonitorEnter()
monitorExit()
compareAndSwapInt()
putOrderedInt()
Arrays
arrayBaseOffset()
arrayIndexScale()
Memory
allocateMemory()
copyMemory()
freeMemory()
getAddress() – not guaranteed after GC
getInt()/putInt()
getBoolean()/putBoolean()
getByte()/putByte()
getShort()/putShort()
getLong()/putLong()
getFloat()/putFloat()
getDouble()/putDouble()
getObjectVolatile()/putObjectVolatile()
Used by
Tungsten
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Traditional Java Object Row Layout
4-byte String
Multi-field Object
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Custom Data Structures for Workload
UnsafeRow
(Dense Binary Row)
TaskMemoryManager
(Virtual Memory Address)
BytesToBytesMap
(Dense Binary HashMap)
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Dense, 8-bytes per field (word-aligned)
Key
Ptr
AlphaSort-Style (Key + Pointer)
OS-Style Memory Paging
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UnsafeRow Layout Example
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Pre-Tungsten
Tungsten
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Custom Memory Management
o.a.s.memory.
TaskMemoryManager & MemoryConsumer
Memory management: virtual memory allocation, pageing
Off-heap: direct 64-bit address
On-heap: 13-bit page num + 27-bit page offset
o.a.s.shuffle.sort.
PackedRecordPointer
64-bit word
(24-bit partition key, (13-bit page num, 27-bit page offset))
o.a.s.unsafe.types.
UTF8String
Primitive Array[Byte]
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2^13 pages * 2^27 page size = 1 TB RAM per Task
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UnsafeFixedWidthAggregationMap
Aggregations
o.a.s.sql.execution.
UnsafeFixedWidthAggregationMap
Uses BytesToBytesMap
In-place updates of serialized data
No object creation on hot-path
Improved external agg support
No OOM’s for large, single key aggs
o.a.s.sql.catalyst.expression.codegen.
GenerateUnsafeRowJoiner
Combine 2 UnsafeRows into 1
o.a.s.sql.execution.aggregate.
TungstenAggregate & TungstenAggregationIterator
Operates directly on serialized, binary UnsafeRow
2 Steps: hash-based agg (grouping), then sort-based agg
Supports spilling and external merge sorting
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Equality
Bitwise comparison on UnsafeRow
No need to calculate equals(), hashCode()
Row 1
Equals!
Row 2
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Joins
Surprisingly, not many code changes
o.a.s.sql.catalyst.expressions.
UnsafeProjection
Converts InternalRow to UnsafeRow
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Sorting
o.a.s.util.collection.unsafe.sort.
UnsafeSortDataFormat
UnsafeInMemorySorter
UnsafeExternalSorter
RecordPointerAndKeyPrefix
UnsafeShuffleWriter
AlphaSort-Style Cache Friendly
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Ptr
Key-Prefix
2x CPU Cache-line Friendly!
Using multiple subclasses of SortDataFormat
simultaneously will prevent JIT inlining.
This affects sort & shuffle performance.
Supports merging compressed records
if compression CODEC supports it (LZF)
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Spilling
Efficient Spilling
Exact data size is known
No need to maintain heuristics & approximations
Controls amount of spilling
Spill merge on compressed, binary records!
If compression CODEC supports it
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UnsafeFixedWidthAggregationMap.getPeakMemoryUsedBytes()
Exact Peak Memory
for Spark Jobs
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Code Generation
Problem
Boxing causes excessive object creation
Expensive expression tree evals per row
JVM can’t inline polymorphic impls
Solution
Codegen by-passes virtual function calls
Defer source code generation to each operator, UDF, UDAF
Use Scala quasiquote macros for Scala AST source code gen
Rewrite and optimize code for overall plan, 8-byte align, etc
Use Janino to compile generated source code into bytecode
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Spark SQL UDF Code Generation
100+ UDFs now generating code
More to come in Spark 1.6+
Details in
SPARK-8159, SPARK-9571
Each Implements
Expression.genCode()!
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Creating a Custom UDF with Codegen
Study existing implementations
https://github.com/apache/spark/pull/7214/files
Extend base trait
o.a.s.sql.catalyst.expressions.Expression.genCode()
Register the function
o.a.s.sql.catalyst.analysis.FunctionRegistry.registerFunction()
Augment DataFrame with new UDF (Scala implicits)
o.a.s.sql.functions.scala
Don’t forget about Python!
python.pyspark.sql.functions.py
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Who Benefits from Project Tungsten?
Users of DataFrames
All Spark SQL Queries
Catalyst
All RDDs
Serialization, Compression, and Aggregations
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Project Tungsten Performance Results
Query Time
Garbage
Collection
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OOM’d on
Large Dataset!
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Presentation Outline
Spark Core: Tuning & Mechanical Sympathy
Spark SQL: Query Optimizing & Catalyst
Spark Streaming: Scaling & Approximations
Spark ML: Featurizing & Recommendations
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Spark SQL: Query Optimizing & Catalyst
Explore DataFrames/Datasets/DataSources, Catalyst
Review Partitions, Pruning, Pushdowns, File Formats
Create a Custom DataSource API Implementation
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DataFrames
Inspired by R and Pandas DataFrames
Schema-aware
Cross language support
SQL, Python, Scala, Java, R
Levels performance of Python, Scala, Java, and R
Generates JVM bytecode vs serializing to Python
DataFrame is container for logical plan
Lazy transformations represented as tree
Only logical plan is sent from Python -> JVM
Only results returned from JVM -> Python
UDF and UDAF Support
Custom UDF support using registerFunction()
Experimental UDAF support (ie. HyperLogLog)
Supports existing Hive metastore if available
Small, file-based Hive metastore created if not available
*DataFrame.rdd returns underlying RDD if needed
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Use DataFrames
instead of RDDs!!
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Spark and Hive
Early days, Shark was “Hive on Spark”
Hive Optimizer slowly replaced with Catalyst
Always use HiveContext – even if not using Hive!
If no Hive, a small Hive metastore file is created
Spark 1.5+ supports all Hive versions 0.12+
Separate classloaders for isolation
Breaks dependency between Spark internal Hive
version
and User’s external Hive version
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Catalyst Optimizer
Optimize DataFrame Transformation Tree
Subquery elimination: use aliases to collapse subqueries
Constant folding: replace expression with constant
Simplify filters: remove unnecessary filters
Predicate/filter pushdowns: avoid unnecessary data load
Projection collapsing: avoid unnecessary projections
Create Custom Rules
Rules are Scala Case Classes
val newPlan = MyFilterRule(analyzedPlan)
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Implements
oas.sql.catalyst.rules.Rule
Apply to any plan stage
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DataSources API
Relations (o.a.s.sql.sources.interfaces.scala)
BaseRelation (abstract class): Provides schema of data
TableScan (impl): Read all data from source
PrunedFilteredScan (impl): Column pruning & predicate pushdowns
InsertableRelation (impl): Insert/overwrite data based on SaveMode
RelationProvider (trait/interface): Handle options, BaseRelation factory
Execution (o.a.s.sql.execution.commands.scala)
RunnableCommand (trait/interface): Common commands like EXPLAIN
ExplainCommand(impl: case class)
CacheTableCommand(impl: case class)
Filters (o.a.s.sql.sources.filters.scala)
Filter (abstract class): Handles all predicates/filters supported by this source
EqualTo (impl)
GreaterThan (impl)
StringStartsWith (impl)
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Native Spark SQL DataSources
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Query Plan Debugging
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gendersCsvDF.select($"id", $"gender").filter("gender != 'F'").filter("gender != 'M'").explain(true)
DataFrame.queryExecution.logical
DataFrame.queryExecution.analyzed
DataFrame.queryExecution.optimizedPlan
DataFrame.queryExecution.executedPlan
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Query Plan Visualization & Metrics
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Effectiveness
of Filter
CPU Cache
Friendly
Binary Format
Cost-based
Join Optimization
Similar to
MapReduce
Map-side Join
Peak Memory for
Joins and Aggs
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JSON Data Source
DataFrame
val ratingsDF = sqlContext.read.format("json")
.load("file:/root/pipeline/datasets/dating/ratings.json.bz2")
-- or –
val ratingsDF = sqlContext.read.json
("file:/root/pipeline/datasets/dating/ratings.json.bz2")
SQL Code
CREATE TABLE genders USING json
OPTIONS
(path "file:/root/pipeline/datasets/dating/genders.json.bz2")
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json() convenience method
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JDBC Data Source
Add Driver to Spark JVM System Classpath
$ export SPARK_CLASSPATH=<jdbc-driver.jar>
DataFrame
val jdbcConfig = Map("driver" -> "org.postgresql.Driver",
"url" -> "jdbc:postgresql:hostname:port/database",
"dbtable" -> ”schema.tablename")
df.read.format("jdbc").options(jdbcConfig).load()
SQL
CREATE TABLE genders USING jdbc
OPTIONS (url, dbtable, driver, …)
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Parquet Data Source
Configuration
spark.sql.parquet.filterPushdown=true
spark.sql.parquet.mergeSchema=true
spark.sql.parquet.cacheMetadata=true
spark.sql.parquet.compression.codec=[uncompressed,snappy,gzip,lzo]
DataFrames
val gendersDF = sqlContext.read.format("parquet")
.load("file:/root/pipeline/datasets/dating/genders.parquet")
gendersDF.write.format("parquet").partitionBy("gender")
.save("file:/root/pipeline/datasets/dating/genders.parquet")
SQL
CREATE TABLE genders USING parquet
OPTIONS
(path "file:/root/pipeline/datasets/dating/genders.parquet")
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ORC Data Source
Configuration
spark.sql.orc.filterPushdown=true
DataFrames
val gendersDF = sqlContext.read.format("orc")
.load("file:/root/pipeline/datasets/dating/genders")
gendersDF.write.format("orc").partitionBy("gender")
.save("file:/root/pipeline/datasets/dating/genders")
SQL
CREATE TABLE genders USING orc
OPTIONS
(path "file:/root/pipeline/datasets/dating/genders")
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Third-Party Spark SQL DataSources
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spark-packages.org
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CSV DataSource (Databricks)
Github
https://github.com/databricks/spark-csv
Maven
com.databricks:spark-csv_2.10:1.2.0
Code
val gendersCsvDF = sqlContext.read
.format("com.databricks.spark.csv")
.load("file:/root/pipeline/datasets/dating/gender.csv.bz2")
.toDF("id", "gender")
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toDF() is required if CSV does not contain header
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ElasticSearch DataSource (Elastic.co)
Github
https://github.com/elastic/elasticsearch-hadoop
Maven
org.elasticsearch:elasticsearch-spark_2.10:2.1.0
Code
val esConfig = Map("pushdown" -> "true", "es.nodes" -> "<hostname>",
"es.port" -> "<port>")
df.write.format("org.elasticsearch.spark.sql”).mode(SaveMode.Overwrite)
.options(esConfig).save("<index>/<document-type>")
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Elasticsearch Tips
Change id field to not_analyzed to avoid indexing
Use term filter to build and cache the query
Perform multiple aggregations in a single request
Adapt scoring function to current trends at query time
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AWS Redshift Data Source (Databricks)
Github
https://github.com/databricks/spark-redshift
Maven
com.databricks:spark-redshift:0.5.0
Code
val df: DataFrame = sqlContext.read
.format("com.databricks.spark.redshift")
.option("url", "jdbc:redshift://<hostname>:<port>/<database>…")
.option("query", "select x, count(*) my_table group by x")
.option("tempdir", "s3n://tmpdir")
.load(...)
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UNLOAD and copy to tmp
bucket in S3 enables
parallel reads
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DB2 and BigSQL DataSources (IBM)
Coming Soon!
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Cassandra DataSource (DataStax)
Github
https://github.com/datastax/spark-cassandra-connector
Maven
com.datastax.spark:spark-cassandra-connector_2.10:1.5.0-M1
Code
ratingsDF.write
.format("org.apache.spark.sql.cassandra")
.mode(SaveMode.Append)
.options(Map("keyspace"->"<keyspace>",
"table"->"<table>")).save(…)
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Cassandra Pushdown Support
spark-cassandra-connector/…/o.a.s.sql.cassandra.PredicatePushDown.scala
Pushdown Predicate Rules
1. Only push down no-partition key column predicates with =, >, <, >=, <= predicate
2. Only push down primary key column predicates with = or IN predicate.
3. If there are regular columns in the pushdown predicates, they should have
at least one EQ expression on an indexed column and no IN predicates.
4. All partition column predicates must be included in the predicates to be pushed down,
only the last part of the partition key can be an IN predicate. For each partition column,
only one predicate is allowed.
5. For cluster column predicates, only last predicate can be non-EQ predicate
including IN predicate, and preceding column predicates must be EQ predicates.
If there is only one cluster column predicate, the predicates could be any non-IN predicate.
6. There is no pushdown predicates if there is any OR condition or NOT IN condition.
7. We're not allowed to push down multiple predicates for the same column if any of them
is equality or IN predicate.
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New Cassandra DataSource
By-pass CQL optimized for transactional data
Instead, do bulk reads/writes directly on SSTables
Similar to 5 year old Netflix Open Source project Aegisthus
Promotes Cassandra to first-class Analytics Option
Potentially only part of DataStax Enterprise?!
Please mail a nasty letter to your local DataStax office
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Rumor of REST DataSource (Databricks)
Coming Soon?
Ask Michael Armbrust
Spark SQL Lead @ Databricks
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Custom DataSource (Me and You!)
Coming Right Now!
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DEMO ALERT!!
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Create a Custom DataSource
Study Existing Native & Third-Party Data Sources
Native
Spark JDBC (o.a.s.sql.execution.datasources.jdbc)
class JDBCRelation extends BaseRelation
with PrunedFilteredScan
with InsertableRelation
Third-Party
DataStax Cassandra (o.a.s.sql.cassandra)
class CassandraSourceRelation extends BaseRelation
with PrunedFilteredScan
with InsertableRelation!
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Contribute a Custom Data Source
spark-packages.org
Managed by
Contains links to external github projects
Ratings and comments
Declare Spark version support for each package
Examples
https://github.com/databricks/spark-csv
https://github.com/databricks/spark-avro
https://github.com/databricks/spark-redshift
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Parquet Columnar File Format
Based on Google Dremel
Collaboration with Twitter and Cloudera
Self-describing, evolving schema
Fast columnar aggregation
Supports filter pushdowns
Columnar storage format
Excellent compression
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Types of Compression
Run Length Encoding: Repeated data
Dictionary Encoding: Fixed set of values
Delta, Prefix Encoding: Sorted data
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Demonstrate File Formats, Partition Schemes, and Query Plans
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Hive JDBC ODBC ThriftServer
Allow BI Tools to Query and Process Spark Data
Register Permanent Table
CREATE TABLE ratings(fromuserid INT, touserid INT, rating INT)
USING org.apache.spark.sql.json
OPTIONS (path "datasets/dating/ratings.json.bz2")
Register Temp Table
ratingsDF.registerTempTable("ratings_temp")
Configuration
spark.sql.thriftServer.incrementalCollect=true
spark.driver.maxResultSize > 10gb (default)
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Demo!
Query and Process Spark Data from BI Tools
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Presentation Outline
Spark Core: Tuning & Mechanical Sympathy
Spark SQL: Query Optimizing & Catalyst
Spark Streaming: Scaling & Approximations
Spark ML: Featurizing & Recommendations
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Spark Streaming: Scaling & Approximations
Discuss Delivery Guarantees, Parallelism, and Stability
Compare Receiver and Receiver-less Impls
Demonstrate Stream Approximations
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Non-Parallel Receiver Implementation
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Receiver Implementation (Kinesis)
KinesisRDD partitions store relevant offsets
Single receiver required to see all data/offsets
Kinesis offsets not deterministic like Kafka
Partitions rebuild from Kinesis using offsets
No Write Ahead Log (WAL) needed
Optimizes happy path by avoiding the WAL
At least once delivery guarantee
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Parallel Receiver-less Implementation (Kafka)
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Receiver-less Implementation (Kafka)
KafkaRDD partitions store relevant offsets
Each partition acts as a Receiver
Tasks/Executors pull from Kafka in parallel
Partitions rebuild from Kafka using offsets
No Write Ahead Log (WAL) needed
Optimizes happy path by avoiding the WAL
At least once delivery guarantee
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Maintain Stability of Stream Processing
Rate Limiting
Since Spark 1.2
Fixed limit on number of messages per second
Potential to drops messages on the floor
Back Pressure
Since Spark 1.5 (TypeSafe Contribution)
More dynamic than rate limiting
Push back on reliable, buffered source (Kafka, Kinesis)
Fundamentals of Control Theory and Observability
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Streaming Approximations
HyperLogLog and CountMin Sketch
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HyperLogLog (HLL) Approx Distinct Count
Approximate count distinct
Twitter’s Algebird
Better than HashSet
Low, fixed memory
Only 1.5K, 2% error,10^9 counts (tunable)
Redis HLL: 12K per key, 0.81%, 2^64 counts
Spark’s countApproxDistinctByKey()
Streaming example in Spark codebase
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http://research.neustar.biz/
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CountMin Sketch (CMS) Approx Count
Approximate count
Twitter’s Algebird
Better than HashMap
Low, fixed memory
Known error bounds
Large num counters
Streaming example in Spark codebase
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Demo!
Using HLL and CMS for Streaming Count Approximations
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Monte Carlo Simulations
From Manhattan Project (Atomic bomb)
Simulate movement of neutrons
Law of Large Numbers (LLN)
Average of results of many trials
Converge on expected value
SparkPi example in Spark codebase
1 Argument: # of trials
Pi ~= # red dots
/ # total dots
* 4
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Demo!
Using a Monte Carlo Simulation to Estimate Pi
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Streaming Best Practices
Get Data Out of Streaming ASAP
Processing interval may exceed batch interval
Leads to unstable streaming system
Please Don’t…
Use updateStateByKey() like an in-memory DB
Put streaming jobs on the request/response hot path
Use Separate Jobs for Different Batch Intervals
Small Batch Interval: Store raw data (Redis, Cassandra, etc)
Medium Batch Interval: Transform, join, process data
High Batch Interval: Model training
Gotchas
Tune streamingContext.remember()
Use Approximations!!
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Presentation Outline
Spark Core: Tuning & Mechanical Sympathy
Spark SQL: Query Optimizing & Catalyst
Spark Streaming: Scaling & Approximations
Spark ML: Featurizing & Recommendations
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Spark ML: Featurizing & Recommendations
Understand Similarity and Dimension Reduction
Demonstrate Sampling and Bucketing
Generate Recommendations
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Live, Interactive Demo!
sparkafterdark.com
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Audience Participation Needed!!
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->
You are
here
->
Audience Instructions
Navigate to sparkafterdark.com
Click 3 actresses and 3 actors
Wait for us to analyze together!
Note: This is totally anonymous!!
Project Links
https://github.com/fluxcapacitor/pipeline
https://hub.docker.com/r/fluxcapacitor
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Similarity
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Types of Similarity
Euclidean
Linear-based measure
Suffers from Magnitude bias
Cosine
Angle-based measure
Adjusts for magnitude bias
Jaccard
Set intersection / union
Suffers Popularity bias
Log Likelihood
Netflix “Shawshank” Problem
Adjusts for popularity bias
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Ali Matei Reynold Patrick Andy
Kimberly 1 1 1 1
Leslie 1 1!
Meredith 1 1 1
Lisa 1 1 1
Holden 1 1 1 1 1
z!
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All-Pairs Similarity Comparison
Compare everything to everything
aka. “pair-wise similarity” or “similarity join”
Naïve shuffle: O(m*n^2); m=rows, n=cols
Minimize shuffle through approximations!
Reduce m (rows)
Sampling and bucketing
Reduce n (cols)
Remove most frequent value (ie.0)
Principle Component Analysis
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Dimension reduction!!
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Dimension Reduction
Sampling and Bucketing
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Reduce m: DIMSUM Sampling
“Dimension Independent Matrix Square Using MR”
Remove rows with low similarity probability
MLlib: RowMatrix.columnSimilarities(…)
Twitter: 40% efficiency gain vs. Cosine Similarity
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Reduce m: LSH Bucketing
“Locality Sensitive Hashing”
Split m into b buckets
Use similarity hash algorithm
Requires pre-processing of data
Parallel compare bucket contents
O(m*n^2) -> O(m*n/b*b^2);
m=rows, n=cols, b=buckets
ie. 500k x 500k matrix
O(1.25e17) -> O(1.25e13); b=50
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github.com/mrsqueeze/spark-hash
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Reduce n: Remove Most Frequent Value
Eliminate most-frequent value
Represent other values with (index,value) pairs
Converts O(m*n^2) -> O(m*nnz^2);
nnz=num nonzeros, nnz << n
Note: Choose most frequent value (may not be 0)
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(index,value)
(index,value)
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Recommendations
Summary Statistics and Top-K Historical Analysis
Collaborative Filtering and Clustering
Text Featurization and NLP
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Types of Recommendations
Non-personalized
No preference or behavior data for user, yet
aka “Cold Start Problem”
Personalized
User-Item Similarity
Items that others with similar prefs have liked
Item-Item Similarity
Items similar to your previously-liked items
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Recommendation Terminology
Feedback
Explicit: like, rating
Implicit: search, click, hover, view, scroll
Feature Engineering
Dimension reduction, polynomial expansion
Hyper-parameter Tuning
K-Folds Cross Validation, Grid Search
Pipelines/Workflows
Chaining together Transformers and Evaluators
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Single Machine ML Algorithms
Stay Local, Distribute As Needed
Helps migration of existing single-node algos to Spark
Convert between Spark and Pandas DataFrames
New “pdspark” package: integration w/ scikitlearn, R
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Non-Personalized Recommendations
Use Aggregate Data to Generate Recommendations
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Top Users by Like Count
“I might like users who have the most-likes overall
based on historical data.”
SparkSQL, DataFrames: Summary Stat, Aggs
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Top Influencers by Like Graph
“I might like the most-influential users in overall like graph.”
GraphX: PageRank
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Demo!
Generate Non-Personalized Recommendations
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Personalized Recommendations
Understand Similarity and Personalized Recommendations
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Like Behavior of Similar Users
“I like the same people that you like.
What other people did you like that I haven’t seen?”
MLlib: Matrix Factorization, User-Item Similarity
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Demo!
Generate Personalized Recommendations using
Collaborative Filtering & Matrix Factorization
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Similar Text-based Profiles as Me
“Our profiles have similar keywords and named entities.
We might like each other!”
MLlib: Word2Vec, TF/IDF, k-skip n-grams
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Similar Profiles to Previous Likes
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“Your profile text has similar keywords and named entities to
other profiles of people I like. I might like you, too!”
MLlib: Word2Vec, TF/IDF, Doc Similarity
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Relevant, High-Value Emails
“Your initial email references a lot of things in my profile.
I might like you for making the effort!”
MLlib: Word2Vec, TF/IDF, Entity Recognition
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^
Her Email< My Profile
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Demo!
Feature Engineering for Text/NLP Use Cases
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The Future of Recommendations
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Eigenfaces: Facial Recognition
“Your face looks similar to others that I’ve liked.
I might like you.”
MLlib: RowMatrix, PCA, Item-Item Similarity
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Image courtesy of http://crockpotveggies.com/2015/02/09/automating-tinder-with-eigenfaces.html
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NLP Conversation Starter Bot!
“If your responses to my generic opening
lines are positive, I may read your profile.”
MLlib: TF/IDF, DecisionTrees,
Sentiment Analysis
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Positive Negative
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Maintaining the Spark
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⑨ Recommendations for Couples
“I want Mad Max. You want Message In a Bottle.
Let’s find something in between to watch tonight.”
MLlib: RowMatrix, Item-Item Similarity
GraphX: Nearest Neighbors, Shortest Path
similar
similar
•
plots ->
<- actors
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Final Recommendation!
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Get Off the Computer & Meet People!
Thank you, Helsinki!!
Chris Fregly @cfregly
IBM Spark Technology Center
San Francisco, CA, USA
Relevant Links
advancedspark.com
Signup for the book & global meetup!
github.com/fluxcapacitor/pipeline
Clone, contribute, and commit code!
hub.docker.com/r/fluxcapacitor/pipeline/wiki
Run all demos in your own environment with Docker!
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More Relevant Links
http://meetup.com/Advanced-Apache-Spark-Meetup
http://advancedspark.com
http://github.com/fluxcapacitor/pipeline
http://hub.docker.com/r/fluxcapacitor/pipeline
http://sortbenchmark.org/ApacheSpark2014.pd
https://databricks.com/blog/2014/11/05/spark-officially-sets-a-new-record-in-large-scale-sorting.html
http://0x0fff.com/spark-architecture-shuffle/
http://www.cs.berkeley.edu/~kubitron/courses/cs262a-F13/projects/reports/project16_report.pdf
http://stackoverflow.com/questions/763262/how-does-one-write-code-that-best-utilizes-the-cpu-cache-to-improve-performance
http://www.aristeia.com/TalkNotes/ACCU2011_CPUCaches.pdf
http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
http://docs.scala-lang.org/overviews/quasiquotes/intro.html
http://lwn.net/Articles/252125/ (Memory Part 2: CPU Caches)
http://lwn.net/Articles/255364/ (Memory Part 5: What Programmers Can Do)
https://www.safaribooksonline.com/library/view/java-performance-the/9781449363512/ch04.html
http://web.eece.maine.edu/~vweaver/projects/perf_events/perf_event_open.html
http://www.brendangregg.com/perf.html
https://perf.wiki.kernel.org/index.php/Tutorial
http://techblog.netflix.com/2015/07/java-in-flames.html
http://techblog.netflix.com/2015/04/introducing-vector-netflixs-on-host.html
http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html#Java
http://sortbenchmark.org/ApacheSpark2014.pdf
https://databricks.com/blog/2014/11/05/spark-officially-sets-a-new-record-in-large-scale-sorting.html
http://0x0fff.com/spark-architecture-shuffle/
http://www.cs.berkeley.edu/~kubitron/courses/cs262a-F13/projects/reports/project16_report.pdf
http://stackoverflow.com/questions/763262/how-does-one-write-code-that-best-utilizes-the-cpu-cache-to-improve-performance
http://www.aristeia.com/TalkNotes/ACCU2011_CPUCaches.pdf
http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
http://docs.scala-lang.org/overviews/quasiquotes/intro.html
http://lwn.net/Articles/252125/ <-- Memory Part 2: CPU Caches
http://lwn.net/Articles/255364/ <-- Memory Part 5: What Programmers Can Do
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What’s Next?
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Power of data. Simplicity of design. Speed of innovation.
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What’s Next?
Autoscaling Spark Workers
Completely Docker-based
Docker Compose and Docker Machine
Lots of Demos and Examples!
Zeppelin & IPython/Jupyter notebooks
Advanced streaming use cases
Advanced ML, Graph, and NLP use cases
Performance Tuning and Profiling
Work closely with Brendan Gregg & Netflix
Surface & share more low-level details of Spark internals
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Upcoming Meetups and Conferences
London Spark Meetup (Oct 12th)
Scotland Data Science Meetup (Oct 13th)
Dublin Spark Meetup (Oct 15th)
Barcelona Spark Meetup (Oct 20th)
Madrid Big Data Meetup (Oct 22nd)
Paris Spark Meetup (Oct 26th)
Amsterdam Spark Summit (Oct 27th)
Brussels Spark Meetup (Oct 30th)
Zurich Big Data Meetup (Nov 2nd)
Geneva Spark Meetup (Nov 5th)
San Francisco Datapalooza.io (Nov 10th)
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San Francisco Advanced Spark (Nov 12th)
Oslo Big Data Hadoop Meetup (Nov 19th)
Helsinki Spark Meetup (Nov 20th)
Stockholm Spark Meetup (Nov 23rd)
Copenhagen Spark Meetup (Nov 25th)
Budapest Spark Meetup (Nov 26th)
Singapore Strata Conference (Dec 1st)
San Francisco Advanced Spark (Dec 8th)
Mountain View Advanced Spark (Dec 10th)
Toronto Spark Meetup (Dec 14th)
Austin Data Days Conference (Jan 2016)
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Power of data. Simplicity of design. Speed of innovation.
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