© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 © 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 1 Under the hoods: How Quarkus and others operate on GraalVM Michael Simons, Java Champion & Staff Software Engineer @ Neo4j Øredev 2022

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Neo4j ● Graph database ● Custom wire protocol with drivers for a broad range of languages ● Web and CLI based shells, including visualization *and nice places like Aachen and Braunschweig and some others like London and San Mateo 2 MATCH (p:Product {name: 'Neo4j'}) -[:IS_CREATED_IN {with: '💙'}]-> (c:City {name: 'Malmö(*)'}) RETURN p, c View from Nordenskiöldsgatan

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 © 2022 Neo4j, Inc. All rights reserved. 3 Why this talk? ● Frameworks do magic all the time (i.e. beans seems to be created from thin air and injected into the right place) ● Java allows access to all kind of things via magic incarnations ● Resources can be easily accessed ➡ Understanding what happens in a software becomes even more important as many things taken for granted do work differently in GraalVM. We want Neo4j to be excellent with GraalVM! “They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance.” - Terry Pratchett in “Equal Rites”

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 4 What is GraalVM? Native image, polyglot runtime, language framework or all of the before? 4

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 5 GraalVM Architecture

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 6 All of it! import static java.lang.System.out; import org.graalvm.polyglot.*; public class HelloJS { public static void main(String... args) { var program = """ const LocalDate = Java.type('java.time.LocalDate') let result = JSON.parse('{"greeting": "Hello, Øredev"}') result = { ...result, "when": LocalDate.now()} """; try (var context = Context.newBuilder().allowAllAccess(true).build()) { var result = context.eval(Source.create("js", program)); out.println( result.getMember("greeting") + " on " + result.getMember("when") ); } } }

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Two execution modes ● JVM Runtime Mode When running programs on the HotSpot JVM, GraalVM defaults to the GraalVM compiler as the top-tier JIT compiler. At runtime, an application is loaded and executed normally on the JVM. The JVM passes bytecodes for Java or any other JVM-native language to the compiler, which compiles that to the machine code and returns it to the JVM. ● Native Image Native Image compiles Java code into a standalone native executable or a native shared library. The Java bytecode that is processed during the build of a native executable includes all application classes, dependencies, third party dependent libraries, and any JDK classes that are required.

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 8 Build-Time- and Runtime-Initialization ● Java semantics requires classes to be initialized at first access => Degrades performances, even hello world initializes a couple of hundred classes ○ Native image can push this to Build-Time, including static state ○ Used to be the default for nearly all classes ● Runtime-Initialization now the default, required classes must be enumerated still ○ JDK classes, including GC, are build-time initialized ○ So are “safe” classes ○ So are explicitly listed classes

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 9 Demo native image public class Hello { public static void main(String... a) { System.out.println("Hello, Øredev"); } }

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 10 Not so fast… public class Hello2 { // native-image --no-fallback Hello2 // java -agentlib:native-image-agent=config-output-dir=c Hello2.java // native-image -H:ReflectionConfigurationFiles=c/reflect-config.json Hello2 public static void main(String... a) throws Exception { var method = Hello2.class .getDeclaredMethod(a.length == 0 ? "greeting1" : a[0]); System.out.println(method.invoke(null)); } static String greeting1() { return "Hello, Øredev"; } static String greeting2() { return "God morgon, Øredev"; } }

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 11 What is Quarkus? 11

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Quarkus ● First appearance 2019 ● Java framework tailored for deployment on Kubernetes. ○ Hotspot and GraalVM on par ● Container first ● unified configuration ● "Batteries included" approach ○ Live coding: Quick turnaround ○ Dev mode ○ Dev containers / (bast on Testcontainers) ● Fast startup, low memory

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 13 All-in towards build-time initialization ● Configuration ● (CDI-Lite) Beans ● Resources ● Entities Done for both JVM mode and Native mode!!! Building a lot of synthetic byte code

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Goals Challenges for (Neo4j) connectivity ● Creating persistent TCP connections ● Discover classes (aka Entities) for OGM ● Evaluate unified configurations ● Discover or enumerate needed resources ● Bossfight SSL

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Create a closed world 15 Or at least, assume one. 15

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Different solutions ● Annotation processing (javax.annotation.processing.*) ● Programmatically (Explicit) ● Functional extension points / Hints (More for the developers building on frameworks and libraries)

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Quarkus ● Programmatically for providers of extensions ● Hints (Annotationen) for end users and direct access to native-image related tools

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Structure and flow of a Quarkus-Extension Augmentation Static Init Runtime Init

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 19 Demo time (Break all the things) 19

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Going with the defaults ● GraalVM has defaulted to Runtime-initialization ● We followed that (move everything Built-Time to Quarkus) and than this

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 The relevance to the ecosystem 21 (and Neo4j) 21

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 The relevance to the ecosystem ● GraalVM and Quarkus challenged a lot of assumptions ● Breath of fresh air, especially for Spring(!) ○ Spring going into a different direction here (Code instead of Bytecode generation) ● As a vendor, we want to not a single obstacle for our users to facilitate the driver in their native program

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 Why? ● Faster startup times, less resource usage ○ (Startup times can be addressed by the CRaC (Coordinated Restore at Checkpoint) Project) ● Elasticity (scale to 0, scale up) ● Lambda ● Probably more secure ● Empowers Java to be used proper in CLI (together with PioCLI and others)

© 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 © 2022 Neo4j, Inc. All rights reserved. Michael Simons aka @rotnroll666 at Øredev 2022 24 Tack! Tooling around GraalVM Email [email protected] Twitter @rotnroll666 Profile https://github.com/michael-simons Ramblings about Frameworks