TDC Connections 2023 - Revolutionize Java DB AppDev with Reactive Streams and Virtual Threads

Revolutionize Java Database App Development with Reactive Streams and Virtual Threads The Developer’s Conference – TDC Connections 2023 Juarez Barbosa Junior - @juarezjunior March 2023 Copyright © 2022, Oracle and/or its affiliates

Agenda • Java App Dev with Oracle Database • Support for the Latest Java Versions • Overview of Oracle DB Access with Java • Oracle JDBC – Sync and Async • Classic Java Platform Threads • Project Loom – Virtual Threads • Virtual Threads - JEP 425 (Preview API) • Demo # 1: Virtual vs Platform Threads • Reactive JDBC - Synchronous vs Asynchronous JDBC • Reactive Streams Ingestion (RSI) • Demo # 2: Reactive Streams Ingestion (RSI) • From Sync to Reactive JDBC: Oracle R2DBC • Demo # 3: Oracle R2DBC • Live Labs/Free Oracle Cloud Account/Oracle ACE Program Copyright © 2022, Oracle and/or its affiliates

Copyright © 2022, Oracle and/or its affiliates Support for the Latest Java Versions • Java 11 - native support, compiled with it • Java 17 - certified • JDBC Standards - 4.2 and 4.3 • JMS 1.1 - latest is 2.0 • GraalVM - native image instrumentation • Reactive Streams - Java Flow API support • Project Loom - Virtual Threads support • Data access is critical in mission-critical apps

Copyright © 2022, Oracle and/or its affiliates Overview of Oracle DB Access with Java User Java Code JDBC Reactive Extension Standard JDBC API R2DBC + 3rd party Reactive Streams Libraries Async call with non-blocking backpressure operators (map, reduce, filters), concurrency modeling, monitoring, tracing Implements Java SE reactive stream interface (Flow) Full Reactive Streams Sync/blocking JDBC calls Java Business Logic User Java code Oracle Database Oracle JDBC driver VTs/lightweight JDBC calls

Copyright © 2022, Oracle and/or its affiliates Oracle JDBC – Sync and Async ⚫ Reactive Programming − Asynchronous database access with non-blocking network I/O − Oracle R2DBC + Oracle JDBC Reactive Extensions + Oracle Reactive Streams Ingestion − Application call stack must be fully asynchronous − Libraries are here to support it: Reactor, RxJava, Akka, Vert.x ⚫ Project Loom/Virtual Threads − Synchronous database access with lightweight threads − Standard JDBC + Virtual Threads − Client application call stack may use conventional (synchronous) code − Libraries must be compatible with Virtual Threads − Oracle instrumented the Oracle JDBC 21c driver to support Virtual Threads

Copyright © 2022, Oracle and/or its affiliates Classic Java Platform Threads ⚫ Blocking Threads ⚫ A JDBC call blocks a thread for 100’s of milliseconds (thread-per-request style) ⚫ Thread count increases linearly with the number of JDBC calls ⚫ Performance degrades as the number of threads increases ⚫ 1 MB of stack memory per thread ⚫ Scheduling many platform threads is expensive ⚫ Preemptive scheduling vs time-slicing

Copyright © 2022, Oracle and/or its affiliates Virtual Threads - JEP 425 (Preview API) ⚫ Virtual Threads ⚫ Lightweight threads that dramatically reduce the effort of writing, maintaining, and observing high-throughput concurrent applications ⚫ Enable applications written in the simple thread-per-request style to scale with near- optimal hardware utilization ⚫ Enable existing code that uses the java.lang.Thread API to adopt virtual threads with minimal change ⚫ Enable easy troubleshooting, debugging, and profiling of virtual threads with existing JDK tools ⚫ Do not remove the traditional implementation of threads ⚫ Do not alter the basic concurrency model of Java

Copyright © 2022, Oracle and/or its affiliates Demo # 1: Virtual vs Platform Threads ⚫ Virtual Threads versus Platform Threads ⚫ JEP 425 Virtual Threads (Project) ⚫ Runs on Java 19 (Preview API) ⚫ javac --release 19 --enable-preview ⚫ java --enable-preview ⚫ Comparison of OS resources consumption (Threads only + JDBC) ⚫ Oracle JDBC Driver 21c instrumented to support Virtual Threads ⚫ API is Oracle JDBC with the Java SE library (Executor, ThreadFactory)

Copyright © 2022, Oracle and/or its affiliates Reactive JDBC - Synchronous vs Asynchronous JDBC Setup Blocking Handle Result Setup Non-Blocking Handle Result Synchronous JDBC Setup Blocking Handle Result Setup Non-Blocking Handle Result Setup Non-Blocking Handle Result Reactive JDBC Database Setup Blocking Handle Result Database

Copyright © 2022, Oracle and/or its affiliates Reactive Streams Ingestion (RSI) ⚫ Java Library for Reactive Streams Ingestion ⚫ Streaming capability: Ingest data in an unblocking, and reactive way from a large group of clients ⚫ Group records through RAC (Real App Clusters), and Shard affinity using native UCP (Universal Connection Pool) ⚫ Optimize CPU allocation while decoupling record Processing from I/O ⚫ Fastest insert method for the Oracle Database through Direct Path Insert, bypassing SQL and writing directly into the DB files

Copyright © 2022, Oracle and/or its affiliates Demo # 2: Reactive Streams Ingestion (RSI) Container Pipelines, Jenkins, etc. Build Test Push Push Docker images to Registry Cloud Infrastructur e Registry Container Engine for Kubernetes Pull images from Registry Deploy images to production Kubernetes worker nodes Containers running microservices deployed over Kubernetes ORACLE CLOUD INFRASTRUCTURE ATP, ADW, ATP-D, AFDW-D Memoptimized Rowstore RSI Runtime: Non- blocking, optimized library for streaming data through Direct Path, Shard & RAC/FAN support. HTTP / REST Engine over Helidon Define build for CI/CD toolchain gRPC / AMQP / MQTT Engines Microservices Files / Logs IoT Devices / Apps cv MQTT gRPC AMQP HTTP / REST JDBC Direct Path INSERT Record Streaming over multiple protocols.

Copyright © 2022, Oracle and/or its affiliates From Sync to Reactive JDBC: Oracle R2DBC static String queryJdbc(java.sql.Connection connection) throws SQLException { try (java.sql.Statement statement = connection.createStatement()) { ResultSet resultSet = statement.executeQuery("SELECT * FROM CUSTOMERS"); if (resultSet.next()) return resultSet.getString(1); else throw new NoSuchElementException("Query returned zero rows"); } } static Publisher<String> queryR2dbc(io.r2dbc.spi.Connection connection) { return Flux.from(connection.createStatement( "SELECT * FROM CUSTOMERS") .execute()) .flatMap(result -> result.map(row -> row.get(0, String.class))) .switchIfEmpty(Flux.error( new NoSuchElementException("Query returned zero rows"))); }

Copyright © 2022, Oracle and/or its affiliates Demo # 3: Oracle R2DBC ⚫ Oracle Reactive Relational Database Connectivity (R2DBC) ⚫ Oracle R2DBC Driver is a Java library that supports reactive Programming with Oracle Database ⚫ It implements the R2DBC Service Provider Interface (SPI) as specified by the Reactive Relational Database Connectivity (R2DBC) ⚫ The R2DBC SPI exposes Reactive Streams as an abstraction for Remote database operations ⚫ The sample code uses Project Reactor. It could use RxJava, Akka, or any RS library ⚫ Runs on Java 11+

Virtual Threads or Reactive? • Oracle JDBC supports both! • Want Virtual Threads? • Oracle JDBC has been “Virtual Thread Compatible” since 21.1.0.0 • Want Reactive? • Oracle R2DBC 1.0.0 is available now • Consume Flow interfaces directly from Oracle JDBC’s Reactive Extensions Copyright © 2022, Oracle and/or its affiliates

Virtual Threads or Reactive? • Benefits of Virtual Threads: • Easier to read and write • Easier to debug • Integration with JDK tools • Limitations of Virtual Threads: • Still a preview feature in JDK 19 • Some libraries are not compatible Copyright © 2022, Oracle and/or its affiliates Benefits of Reactive: • Available now. Supported on JDK 11 • Reactive Libraries (Reactor, RxJava, Akka, Vert.x) • Stream-like API with a functional style • Low-level concurrency is handled for you (locks, atomics, queues). Limitations of Reactive: • Steep learning curve • Harder to read and write • Harder to debug

Copyright © 2022, Oracle and/or its affiliates References • JDK 19 / Project Loom • JDK 19 - https://openjdk.org/projects/jdk/19/ • Loom - https://openjdk.org/projects/loom/ • JEP 425 Virtual Threads (Preview) - https://bugs.openjdk.org/browse/JDK-8277131 • Introduction to Oracle JDBC 21c Driver Support for Virtual Threads - https://bit.ly/3UlNJWP • Reactive Streams Ingestion Library • Getting Started with the Java library for Reactive Streams Ingestion (RSI) - https://bit.ly/3rEiRnC • High-throughput stream processing with the Java Library for Reactive Streams Ingestion (RSI), Virtual Threads, and the Oracle ATP Database - https://bit.ly/3rATCTd • RSI - https://docs.oracle.com/en/database/oracle/ • R2DBC • Oracle R2DBC Driver – https://github.com/oracle/oracle-r2dbc • Develop Java applications with Oracle Database • JDBC – https://www.oracle.com/database/technologies/appdev/jdbc.html

About me • Juarez Barbosa Junior - @juarezjunior • Senior Principal Java Developer Evangelist • 27 years of experience • SW Engineering, Developer Relations • Microsoft, Oracle, IBM, Nokia, Unisys, Accenture, and a few startups • Microsoft Azure Developer Relations Lead • IBM Watson Tech Evangelist & Cloud Rockstar • IBM Mobile Tech Evangelist & Global Thought Leader • Nokia Developers Global Champion • Lead Software/DevOps Architect • Expertise • Java, Cloud, DevOps, Cloud-native, Blockchain Copyright © 2022, Oracle and/or its affiliates

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TDC Connections 2023 - Revolutionize Java DB AppDev with Reactive Streams and Virtual Threads

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