GraalVM Undertow Issue

This repository reproduces an issue with GraalVM and Undertow that makes the native image failing at runtime

issue confirmed with GraalVM 21.0.0 as well

✅ issue fixed with GraalVM 21.3.0

build native image

$ mvn clean package -Pnative

run (leading to error)

$ mvn clean package -Pnative
$ ./target/graalvm-undertow-issue-native

Nov 24, 2020 11:48:10 AM io.undertow.Undertow start
INFO: starting server: Undertow - 2.2.2.Final
Nov 24, 2020 11:48:10 AM org.xnio.Xnio <clinit>
INFO: XNIO version 3.8.0.Final
Nov 24, 2020 11:48:10 AM org.xnio.nio.NioXnio <clinit>
INFO: XNIO NIO Implementation Version 3.8.0.Final
Nov 24, 2020 11:48:10 AM org.jboss.threads.Version <clinit>
INFO: JBoss Threads version 3.1.0.Final
Exception in thread "main" com.oracle.svm.core.jdk.UnsupportedFeatureError: Unsupported method of Unsafe
	at com.oracle.svm.core.util.VMError.unsupportedFeature(VMError.java:87)
	at jdk.internal.misc.Unsafe.staticFieldBase(Unsafe.java:236)
	at sun.misc.Unsafe.staticFieldBase(Unsafe.java:677)
	at org.jboss.threads.EnhancedQueueExecutor.<clinit>(EnhancedQueueExecutor.java:295)
	at com.oracle.svm.core.classinitialization.ClassInitializationInfo.invokeClassInitializer(ClassInitializationInfo.java:351)
	at com.oracle.svm.core.classinitialization.ClassInitializationInfo.initialize(ClassInitializationInfo.java:271)
	at org.xnio.XnioWorker.<init>(XnioWorker.java:139)
	at org.xnio.nio.NioXnioWorker.<init>(NioXnioWorker.java:84)
	at org.xnio.nio.NioXnio.build(NioXnio.java:233)
	at org.xnio.XnioWorker$Builder.build(XnioWorker.java:1191)
	at org.xnio.Xnio.createWorker(Xnio.java:481)
	at org.xnio.Xnio.createWorker(Xnio.java:463)
	at org.xnio.Xnio.createWorker(Xnio.java:450)
	at io.undertow.Undertow.start(Undertow.java:122)
	at com.softinstigate.App.main(App.java:25)

Analysis of error

The error comes from jboss-threads.

Here the static class initializer of EnhancedQueueExecutor fails.

The code is:

static {
        try {
            terminationWaitersOffset = unsafe.objectFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("terminationWaiters"));

            queueSizeOffset = unsafe.objectFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("queueSize"));

            peakThreadCountOffset = unsafe.objectFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("peakThreadCount"));
            activeCountOffset = unsafe.objectFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("activeCount"));
            peakQueueSizeOffset = unsafe.objectFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("peakQueueSize"));

            sequenceBase = unsafe.staticFieldBase(EnhancedQueueExecutor.class.getDeclaredField("sequence"));
            sequenceOffset = unsafe.staticFieldOffset(EnhancedQueueExecutor.class.getDeclaredField("sequence"));
        } catch (NoSuchFieldException e) {
            throw new NoSuchFieldError(e.getMessage());
        }
    }

The offending code line is:

static volatile int sequence = 1;

sequenceBase = unsafe.staticFieldBase(EnhancedQueueExecutor.class.getDeclaredField("sequence"));

The unsafe class is from JBossExecutors

workarounds

1 - remove unsafe calls and disable jboss executors (preferred)

see:

• https://github.com/SoftInstigate/graalvm-undertow-issue/commit/ad36bd2d5b5397800f3494613e7fecc22615beab
• oracle/graal#3020

2 - downgrade Xnio

downgrade Xnio to v3.5.9 (current is v3.8.0)

            <!-- downgraded XNio for native-image.
                 in version 3.6.0.Final xnio introduces dependency to org.jboss.threads:jboss-threads:2.3.0.Beta2
                 this generates runtime error with native image
                 see https://github.com/SoftInstigate/graalvm-undertow-issue
            -->
            <!-- downgraded for native-image -->
            <dependency>
                <groupId>org.jboss.xnio</groupId>
                <artifactId>xnio-api</artifactId>
                <version>3.5.9.Final</version>
            </dependency>
            <!-- downgraded for native-image -->
            <dependency>
                <groupId>org.jboss.xnio</groupId>
                <artifactId>xnio-nio</artifactId>
                <version>3.5.9.Final</version>
            </dependency>