Instant Netty startup using GraalVM's Native Image Generation

The purpose of this repo is to walk you through generating a native executable image from a simple Netty application using the GraalVM native-image tool.

Setting up the development environment

To set up your development environment you first need to download GraalVM. Either the Comunity Edition or the Enterprise Edition will work for the purpose of this example. The GraalVM download contains a full JVM plus few other utilities like the native-image tool. Then you need to set your JAVA_HOME to point to GraalVM:

$ export JAVA_HOME=<graalvm-download-location>/graalvm-1.0.0-rc12

Then you need to add GraalVM to your path:

$ export PATH=$JAVA_HOME/bin:$PATH

Now you can run the native-image tool:

$ native-image --help

GraalVM native-image building tool

This tool can be used to generate an image that contains ahead-of-time compiled Java code.
...

Alternativelly, you could build native-image from source following the quick start guide.

For compilation native-image depends on the local toolchain, so please make sure: glibc-devel, zlib-devel (header files for the C library and zlib) and gcc are available on your system. On the OS that this demo was tested, Ubuntu 16.04, the following command was required to install zlib-devel, the rest of the dependencies being installed out-of-the-box:

$ sudo apt-get install zlib1g-dev

Setting up the project

For the purpose of this demo we copied the HttpHelloWorldServer example from the netty examples repo.

The example is built with Maven. The pom.xml file declares an svm.jar dependency:

<dependency>
  <groupId>com.oracle.substratevm</groupId>
  <artifactId>svm</artifactId>
  <version>1.0.0-rc12</version>
  <scope>provided</scope>
</dependency>

The svm.jar library contains all the code needed to compile the substitutions required for Netty. The other required library, graal-sdk.jar, is automatically added to the classpath when you run the javac command shipped with GraalVM.

Now you can build with:

$ mvn clean package

This will create a jar file with all dependencies embedded.

Run Netty on JVM

On the regular JVM you can run as usual using the java command:

$ java -jar target/netty-svm-httpserver-full.jar
Open your web browser and navigate to http://127.0.0.1:8080/

Run Netty with GraalVM Native

To build the native image we use the native-image tool:

$ native-image -jar target/netty-svm-httpserver-full.jar -H:ReflectionConfigurationResources=netty_reflection_config.json -H:Name=netty-svm-http-server --delay-class-initialization-to-runtime=io.netty.handler.codec.http.HttpObjectEncoder -Dio.netty.noUnsafe=true
Build on Server(pid: 29456, port: 26681)
   classlist:     194.15 ms
       (cap):     468.11 ms
       setup:     626.51 ms
  (typeflow):   3,709.95 ms
   (objects):   2,402.43 ms
  (features):      42.58 ms
    analysis:   6,274.84 ms
    universe:     141.76 ms
     (parse):     310.85 ms
    (inline):     658.15 ms
   (compile):   1,782.15 ms
     compile:   3,055.74 ms
       image:     484.51 ms
       write:     132.26 ms
     [total]:  10,936.45 ms

This creates an executable file that is less than 9 MB in size:

$ ls -Gg --block-size=k netty-svm-http-server
-rwxrwxr-x 1 8330K May  8 23:33 netty-svm-http-server

We can now run the executable:

$ ./netty-svm-http-server
Open your web browser and navigate to http://127.0.0.1:8080/

vjovanov/netty-native-demo

Instant Netty startup using GraalVM's Native Image Generation

Setting up the development environment

Setting up the project

Run Netty on JVM

Run Netty with GraalVM Native