Architectural Comparison of Apache Apex and Spark Streaming

WebinarJune 8th 2016

Thomas Weise, Apache Apex PMC@thweise thw@apache.org

Next Gen Stream Data Processing• Data from variety of sources (IoT, Kafka, files, social media etc.)• Unbounded, continuous data streams

ᵒ Batch can be processed as stream (but a stream is not a batch)• (In-memory) Processing with temporal boundaries (windows)• Stateful operations: Aggregation, Rules, … -> Analytics• Results stored to variety of sinks or destinations

ᵒ Streaming application can also serve data with very low latency

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Browser

Web Server

Kafka Input(logs)

Decompress, Parse, Filter

Dimensions Aggregate Kafka

LogsKafka

Batch vs. Streaming

Credit: Gyula Fóra & Márton Balassi: Large-Scale Stream Processing in the Hadoop Ecosystem

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Architecture and FeaturesSpark Streaming Apex

Model micro-batch native streaming/data-in-motion

Language Java, Scala, client bindings Java (Scala)

API declarative compositional (DAG), declarative*

Locality data locality advanced processing locality

Latency high very low (millis)

Throughput very high very high

Scalability scheduler limit horizontal

Partitioning standard advanced (parallel pipes, unifiers)

Connector Library Limited (certification), externally maintained

Rich library of connectors and processors, part of Apex (Malhar)

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OperabilitySpark Streaming Apex

State Management RDD, user code checkpointing

Recovery RDD lineage incremental (buffer server)

Processing Sem. exactly-once* end-to-end exactly-once

Backpressure user configuration Automatic (buffer server memory + disk)

Elasticity yes w/ limited control yes w/ full user control

Dynamic topology no yes

Security Kerberos Kerberos, RBAC*, LDAP*

Multi-tennancy depends on cluster manager YARN, full isolation

DevOps tools basic REST API, DataTorrent RTS

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Apache Apex Features• In-memory stream processing platform

ᵒ Developed since 2012, ASF TLP since 04/2016• Unobtrusive Java API to express (custom) logic• Scale out, distributed, parallel• High throughput & low latency processing• Windowing (temporal boundary)• Reliability, fault tolerance, operability• Hadoop native• Compute locality, affinity• Dynamic updates, elasticity

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Apex Platform Overview

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Apache Apex Malhar Library

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Application Development Model

A Stream is a sequence of data tuplesA typical Operator takes one or more input streams, performs computations & emits one or more output streams

• Each Operator is YOUR custom business logic in java, or built-in operator from our open source library• Operator has many instances that run in parallel and each instance is single-threaded

Directed Acyclic Graph (DAG) is made up of operators and streams

Directed Acyclic Graph (DAG)

Filtered

Stream

Output StreamTuple Tuple

Filtered Stream

Enriched Stream

Enriched

Stream

er

Operator

er

Operator

er

Operator

er

Operator

er

Operator

er

Operator

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Streaming Windows

Application window Sliding window and tumbling window

Checkpoint window No artificial latency

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Event time & Dimensions Computation

(All) : 5t=4:00 : 2t=5:00 : 3

k=A, t=4:00 : 2k=A, t=5:00 : 1k=B, t=5:00 : 2

(All) : 4t=4:00 : 2t=5:00 : 2

k=A, t=4:00 : 2

K=B, t=5:00 : 2

k=At=5:00

(All) : 1t=4:00 : 1

k=A, t=4:00 : 1

k=Bt=5:59

k=Bt=5:00

k=AT=4:30

k=At=4:00

Scalability• Large amount of data to process, arrival at high velocity

ᵒ Pipelining and partitioningᵒ Backpressure

• Partitioningᵒ Run same logic in multiple processes or threadsᵒ Each partition processes a subset of the data

• Apex supports partitioning out of the boxᵒ Different partitioning schemesᵒ Unificationᵒ Static & Dynamic Partitioningᵒ Separation of processing logic from scaling decisions

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PartitioningNxM PartitionsUnifier

0 1 2 3

Logical DAG

0 1 2

1

1 Unifier

1

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Logical Diagram

Physical Diagram with operator 1 with 3 partitions

0

Unifier

1a

1b

1c

2a

2b

Unifier 3

Physical DAG with (1a, 1b, 1c) and (2a, 2b): No bottleneck

Unifier

Unifier0

1a

1b

1c

2a

2b

Unifier 3

Physical DAG with (1a, 1b, 1c) and (2a, 2b): Bottleneck on intermediate Unifier

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Advanced Partitioning

0

1a

1b

2 3 4Unifier

Physical DAG

0 4

3a2a1a

1b 2b 3b

Unifier

Physical DAG with Parallel Partition

Parallel Partition

Container

uopr

uopr1

uopr2

uopr3

uopr4

uopr1

uopr2

uopr3

uopr4

dopr

dopr

doprunifier

unifier

unifier

unifier

Container

Container

NIC

NIC

NIC

NIC

NIC

Container

NIC

Logical Plan

Execution Plan, for N = 4; M = 1

Execution Plan, for N = 4; M = 1, K = 2 with cascading unifiers

Cascading Unifiers

0 1 2 3 4

Logical DAG

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Dynamic Partitioning

• Partitioning change while application is runningᵒ Change number of partitions at runtime based on statsᵒ Determine initial number of partitions dynamically

• Kafka operators scale according to number of kafka partitionsᵒ Supports re-distribution of state when number of partitions changeᵒ API for custom scaler or partitioner

2b

2c

3

2a

2d

1b

1a1a 2a

1b 2b

3

1a 2b

1b 2c 3b

2a

2d

3a

Unifiers not shown

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How dynamic partitioning works• Partitioning decision (yes/no) by trigger (StatsListener)

ᵒ Pluggable component, can use any system or custom metricᵒ Externally driven partitioning example: KafkaInputOperator

• Stateful! ᵒ Uses checkpointed stateᵒ Ability to transfer state from old to new partitions (partitioner, customizable)ᵒ Steps:

• Call partitioner• Modify physical plan, rewrite checkpoints as needed• Undeploy old partitions from execution layer• Release/request container resources• Deploy new partitions (from rewritten checkpoint)

ᵒ No loss of data (buffered)ᵒ Incremental operation, partitions that don’t change continue processing

• API: Partitioner interface

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Fault Tolerance• Operator state is checkpointed to persistent store

ᵒ Automatically performed by engine, no additional coding neededᵒ Asynchronous and distributed ᵒ In case of failure operators are restarted from checkpoint state

• Automatic detection and recovery of failed containersᵒ Heartbeat mechanismᵒ YARN process status notification

• Buffering to enable replay of data from recovered pointᵒ Fast, incremental recovery, spike handling

• Application master state checkpointedᵒ Snapshot of physical (and logical) planᵒ Execution layer change log

• In-memory PubSub• Stores results emitted by operator until committed• Handles backpressure / spillover to local disk• Ordering, idempotency

Operator 1

Container 1

BufferServer

Node 1

Operator 2

Container 2

Node 2

Buffer Server

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Recovery Scenario… EW2, 1, 3, BW2, EW1, 4, 2, 1, BW1

sum0

… EW2, 1, 3, BW2, EW1, 4, 2, 1, BW1sum

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… EW2, 1, 3, BW2, EW1, 4, 2, 1, BW1sum10

… EW2, 1, 3, BW2, EW1, 4, 2, 1, BW1sum

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Processing GuaranteesAt-least-once• On recovery data will be replayed from a previous checkpoint

ᵒ No messages lostᵒ Default, suitable for most applications

• Can be used to ensure data is written once to storeᵒ Transactions with meta information, Rewinding output, Feedback

from external entity, Idempotent operationsAt-most-once• On recovery the latest data is made available to operator

ᵒ Useful in use cases where some data loss is acceptable and latest data is sufficient

Exactly-onceᵒ At-least-once + idempotency + transactional mechanisms (operator

logic) to achieve end-to-end exactly once behavior

End-to-End Exactly Once

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• Becomes important when writing to external systems• Data should not be duplicated or lost in the external system even in

case of application failures• Common external systems

ᵒ Databasesᵒ Filesᵒ Message queues

• Platform support for at least once is a must so that no data is lost• Data duplication must still be avoided when data is replayed from

checkpointᵒ Operators implement the logic dependent on the external systemᵒ Platform provides checkpointing and repeatable windowing

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Data Processing Pipeline ExampleApp Builder

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Monitoring ConsoleLogical View

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Monitoring ConsolePhysical View

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Real-Time DashboardsReal Time Visualization

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Maximize Revenue w/ real-time insightsPubMatic is the leading marketing automation software company for publishers. Through real-time analytics, yield management, and workflow automation, PubMatic enables publishers to make smarter inventory decisions and improve revenue performance

Business Need Apex based Solution Client Outcome

• Ingest and analyze high volume clicks & views in real-time to help customers improve revenue

- 200K events/second data flow

• Report critical metrics for campaign monetization from auction and client logs

- 22 TB/day data generated• Handle ever increasing traffic with

efficient resource utilization• Always-on ad network

• DataTorrent Enterprise platform, powered by Apache Apex

• In-memory stream processing• Comprehensive library of pre-built

operators including connectors• Built-in fault tolerance• Dynamically scalable• Management UI & Data Visualization

console

• Helps PubMatic deliver ad performance insights to publishers and advertisers in real-time instead of 5+ hours

• Helps Publishers visualize campaign performance and adjust ad inventory in real-time to maximize their revenue

• Enables PubMatic reduce OPEX with efficient compute resource utilization

• Built-in fault tolerance ensures customers can always access ad network

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Industrial IoT applicationsGE is dedicated to providing advanced IoT analytics solutions to thousands of customers who are using their devices and sensors across different verticals. GE has built a sophisticated analytics platform, Predix, to help its customers develop and execute Industrial IoT applications and gain real-time insights as well as actions.

Business Need Apex based Solution Client Outcome

• Ingest and analyze high-volume, high speed data from thousands of devices, sensors per customer in real-time without data loss

• Predictive analytics to reduce costly maintenance and improve customer service

• Unified monitoring of all connected sensors and devices to minimize disruptions

• Fast application development cycle• High scalability to meet changing business

and application workloads

• Ingestion application using DataTorrent Enterprise platform

• Powered by Apache Apex• In-memory stream processing• Built-in fault tolerance• Dynamic scalability• Comprehensive library of pre-built

operators• Management UI console

• Helps GE improve performance and lower cost by enabling real-time Big Data analytics

• Helps GE detect possible failures and minimize unplanned downtimes with centralized management & monitoring of devices

• Enables faster innovation with short application development cycle

• No data loss and 24x7 availability of applications

• Helps GE adjust to scalability needs with auto-scaling

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Smart energy applications

Silver Spring Networks helps global utilities and cities connect, optimize, and manage smart energy and smart city infrastructure. Silver Spring Networks receives data from over 22 million connected devices, conducts 2 million remote operations per year

Business Need Apex based Solution Client Outcome

• Ingest high-volume, high speed data from millions of devices & sensors in real-time without data loss

• Make data accessible to applications without delay to improve customer service

• Capture & analyze historical data to understand & improve grid operations

• Reduce the cost, time, and pain of integrating with 3rd party apps

• Centralized management of software & operations

• DataTorrent Enterprise platform, powered by Apache Apex

• In-memory stream processing• Pre-built operator • Built-in fault tolerance• Dynamically scalable• Management UI console

• Helps Silver Spring Networks ingest & analyze data in real-time for effective load management & customer service

• Helps Silver Spring Networks detect possible failures and reduce outages with centralized management & monitoring of devices

• Enables fast application development for faster time to market

• Helps Silver Spring Networks scale with easy to partition operators

• Automatic recovery from failures

Demo / Q&A

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Resources

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• Apache Apex - http://apex.apache.org/• Subscribe - http://apex.apache.org/community.html• Download - https://www.datatorrent.com/download/• Twitter

ᵒ @ApacheApex; Follow - https://twitter.com/apacheapexᵒ @DataTorrent; Follow – https://twitter.com/datatorrent

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ᵒ https://www.datatorrent.com/product/startup-accelerator/

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