Deep learning and streaming in Apache Spark 2.2 by Matei Zaharia

Deep Learning and Streaming in Apache Spark 2.2

Matei Zaharia@matei_zaharia

Evolution of Big Data SystemsTremendous potential, but very hard to use at first:

• Low-level APIs (MapReduce)

• Separate systems for each workload (SQL, ETL, ML, etc)

How Spark Tackled this Problem1) Composable, high-level APIs• Functional programs in Scala, Python, Java, R• Opens big data to many more users

2) Unified engine• Combines batch, interactive, streaming• Simplifies building end-to-end apps

SQLStreaming ML Graph

…

Expanding Spark to New Areas

Structured Streaming

Deep Learning

1

2

Real-Time Applications TodayIncreasingly important to put big data in production• Real-time reporting, model serving, etc

But very hard to build: • Disparate code for streaming & batch• Complex interactions with

external systems• Hard to operate and debug

Goal: unified API for end-to-end continuous appsBatch

Job

Ad-hocQueries

InputStream

AtomicOutput

Continuous Application

Static Data

Batch Jobs

>_

Structured StreamingNew end-to-end streaming API built on Spark SQL• Simple APIs: DataFrames, Datasets and SQL – same as in batch.

Event-time processing and out-of-order data.• End-to-end exactly once: Transactional both in processing & output.• Complete app lifecycle: Code upgrades, ad-hoc queries and more.

Marked GA in Apache Spark 2.2

Simple APIs: Benchmark

7

KStream<String, ProjectedEvent> filteredEvents = kEvents.filter((key, value) -> {return value.event_type.equals("view");

}).mapValues((value) -> {return new ProjectedEvent(value.ad_id, value.event_time);

});

KTable<String, String> kCampaigns = builder.table("campaigns", "campaign-state");KTable<String, CampaignAd> deserCampaigns = kCampaigns.mapValues((value) -> {Map<String, String> campMap = Json.parser.readValue(value);return new CampaignAd(campMap.get("ad_id"), campMap.get("campaign_id"));

});KStream<String, String> joined =filteredEvents.join(deserCampaigns, (value1, value2) -> {return value2.campaign_id;

}, Serdes.String(), Serdes.serdeFrom(new ProjectedEventSerializer(), new ProjectedEventDeserializer()));

KStream<String, String> keyedByCampaign = joined.selectKey((key, value) -> value);KTable<Windowed<String>, Long> counts = keyedByCampaign.groupByKey().count(TimeWindows.of(10000), "time-windows");

Filter by click type and project

Join with campaigns table

Group and windowed count

streams






});

KStream<String, String> keyedByCampaign = joined.selectKey((key, value) -> value);KTable<Windowed<String>, Long> counts =keyedByCampaign.groupByKey().count(TimeWindows.of(10000), "time-windows");

8

DataFrames

Simple APIs: Benchmarkstreams

events.where("event_type = 'view'").join(table("campaigns"), "ad_id").groupBy(

window('event_time, "10 seconds"),'campaign_id)

.count()

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streamsSimple APIs: Benchmark

SQL

SELECT COUNT(*)FROM eventsJOIN campaigns USING ad_idWHERE event_type = 'view'GROUP BY

window(event_time, "10 seconds"),campaign_id)






});

KStream<String, String> keyedByCampaign = joined.selectKey((key, value) -> value);KTable<Windowed<String>, Long> counts =keyedByCampaign.groupByKey().count(TimeWindows.of(10000), "time-windows");

streams

DataFrame,Dataset or SQL

input = spark.readStream.format("kafka").option("subscribe", "topic").load()

result = input.select("device", "signal").where("signal > 15")

result.writeStream.format("parquet").start("dest-path")

Logical Plan

Read from Kafka

Projectdevice, signal

Filtersignal > 15

Write to Kafka

Under the Covers

Structured Streaming automatically incrementalizesthe provided batch computation

Series of IncrementalExecution Plans

Kafka Source

Optimized Operatorcodegen, off-

heap, etc.

KafkaSink

OptimizedPhysical Plan

proc

ess

new

dat

a

t = 1 t = 2 t = 3

proc

ess

new

dat

a

proc

ess

new

dat

a

Structured Streaming reuses the Spark SQL Optimizer

and Tungsten Engine.

11https://data-artisans.com/blog/extending-the-yahoo-streaming-benchmark

Throughput At ~200ms Latency

700K

15M

65M

010203040506070

Kafka Streams

Flink Structured Streaming

Mill

ions

5xlower cost

Performance: Benchmark

What About Latency?Continuous processing mode for execution without microbatches• <1 ms latency (same as per-record streaming systems)• No changes to user code• Proposal in SPARK-20928

Databricks blog post: tinyurl.com/spark-continuous-processing

Structured Streaming Use Cases

Cloud big data platform serving 500+ orgs

Metrics pipeline: 14B events/h on 10 nodes

Dashboards Analyzeusagetrendsinrealtime

Alerts Notifyengineersofcriticalissues

Ad-hocAnalysis Diagnoseissueswhentheyoccur

ETL Clean and store historical data


Cloud big data platform serving 500+ orgs

Metrics pipeline: 14B events/h on 10 nodes

=

Metrics

Filter

ETL

Dashboards

Ad-hocAnalysis

Alerts


Monitor quality of live video in production across dozens of online properties

Analyze data from 1000s of WiFi hotspots to find anomalous behavior

More info: see talks at Spark Summit 2017

Expanding Spark to New Areas

Structured Streaming

Deep Learning

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2

Deep Learning has Huge Potential

Unprecedented ability to work with unstructured data such as images and text

But Deep Learning is Hard to Use

Current APIs (TensorFlow, Keras, BigDL, etc) are low-level• Build a computation graph from scratch• Scale-out typically requires manual parallelization

Hard to expose models in larger applications

Very similar to early big data APIs (MapReduce)

Our GoalEnable an order of magnitude more users to build applications using deep learning

Provide scale & production use out of the box

Deep Learning PipelinesA new high-level API for deep learning that integrates with Apache Spark’s ML Pipelines• Common use cases in just a few lines of code• Automatically scale out on Spark• Expose models in batch/streaming apps & Spark SQL

Builds on existing DL engines (TensorFlow, Keras, BigDL)

Image Loading

from sparkdl import readImagesimage_df = readImages(sample_img_dir)

Applying Popular ModelsPopular pre-trained models included as MLlib Transformers

predictor = DeepImagePredictor(inputCol="image", outputCol="predicted_labels", modelName="InceptionV3")

predictions_df = predictor.transform(image_df)

Fast Model Training via Transfer Learning

Example: identify James Bond cars

Transfer Learning

SoftMaxGIANT PANDA 0.9RED PANDA 0.05RACCOON 0.01…

Classifier

Transfer Learning

DeepImageFeaturizer

Transfer Learning as an ML Pipeline

MLlib Pipeline

ImageLoading Preprocessing Logistic

RegressionDeepImageFeaturizer

Transfer Learning Code

featurizer = DeepImageFeaturizer(modelName="InceptionV3”)lr = LogisticRegression()p = Pipeline(stages=[featurizer, lr])

model = p.fit(train_images_df)

Automatically distributed across cluster!

Transfer Learning Results

Distributed Model Tuning

Distributed Model Tuning CodemyEstimator = KerasImageFileEstimator(

inputCol='input', outputCol='output', modelFile='/model.h5')

params1 = {'batch_size':10, epochs:10}

params2 = {'batch_size':5, epochs:20}

myParamMaps = ParamGridBuilder() \

.addGrid(myEstimator.kerasParams, [params1, params2]).build()

cv = CrossValidator(myEstimator, myEvaluator, myParamMaps)

cvModel = cv.fit()

Sharing and Applying Models

Take a trained model / Pipeline, register a SQL UDF usable by anyone in the organization

In Spark SQL:

registerKerasUDF("my_object_recognition_function", keras_model_file="/mymodels/007model.h5")

select image, my_object_recognition_function(image) as objects from traffic_imgs

Cannowapplyinstreaming,batchorinteractivequeries!

Other Upcoming Features

Distributed training of one model via TensorFlowOnSpark(https://github.com/yahoo/TensorFlowOnSpark)

More built-in data types: text, time series, etc

Scalable Deep Learning made Simple

High-level API for Deep Learning, integrated with MLlib

Scales common tasks with transformers and estimators

Expose deep learning models in MLlib and Spark SQL

Early release of Deep Learning Pipelines:github.com/databricks/spark-deep-learning

ConclusionAs new use cases mature for big data, systems will naturally move from specialized/complex to unified

We’re applying the lessons from early Spark to streaming & DL • High-level, composable APIs• Flexible execution (SQL optimizer, continuous processing)• Support for end-to-end apps

https://spark-summit.org/eu-2017/15% discount code: MateiAMS

Free preview release:dbricks.co/2sK35XT

Deep learning and streaming in Apache Spark 2.2 by Matei Zaharia

Technology

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