Under the hoods: How Quarkus operates with GraalVM demonstrated with Neo4j

Nearly 3 years since the inception many of us have seen amazing demos: How fast Quarkus based applications start, how helpful dev mode is, we have even learned continuous testing. And when going to production, it even works natively on GraalVM. This talk is the story that starts after a small meeting back in early 2019 in London that led to making the Neo4j driver compatible with GraalVM native over to providing a Quarkus extensions for just the connectivity and eventually ending with full support of Neo4j-ObjectGraphMapping framework in Quarkus. We will talk about the mechanisms Quarkus applies to create a closed world assumption that fulfills the needs of GraalVM native, how extensions need to deal with and the different modules being in a Quarkus extension. This talk will help you understanding why things in Quarkus work the way they do and how you can benefit from them. All of that will be demonstrated with Neo4j and the official Java connectivity to the worlds leading Graph database.

Transcript

1. © 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
   

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2. © 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
   

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3. © 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”
   

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4. © 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
   

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

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6. © 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")
   );
   }
   }
   }
   

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7. © 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.
   

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8. © 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
   

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9. © 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");
   }
   }
   

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10. © 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";
    }
    }
    

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

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12. © 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
    

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13. © 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
    

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14. © 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
    

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

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16. © 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)
    

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17. © 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
    

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18. © 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
    

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

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20. © 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
    

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

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22. © 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
    

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23. © 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)
    

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24. © 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 michael.simons@neo4j.com
    Twitter @rotnroll666
    Profile https://github.com/michael-simons
    Ramblings about
    Frameworks
    

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