Merge pull request #49937 from Sanne/JvmChecks

Check for --sun-misc-unsafe-memory-access=allow, log a user friendly warning when not

Author: Sanne

core/deployment/src/main/java/io/quarkus/deployment/steps/CheckJVMparamsProcessor.java

@@ -0,0 +1,16 @@
+package io.quarkus.deployment.steps;
+
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.annotations.ExecutionTime;
+import io.quarkus.deployment.annotations.Record;
+import io.quarkus.deployment.pkg.steps.NativeBuild;
+import io.quarkus.runtime.JVMChecksRecorder;
+
+public class CheckJVMparamsProcessor {
+
+    @BuildStep(onlyIfNot = NativeBuild.class)
+    @Record(ExecutionTime.RUNTIME_INIT)
+    public void recordJvmChecks(JVMChecksRecorder recorder) {
+        recorder.check();
+    }
+}

core/runtime/src/main/java/io/quarkus/runtime/JVMChecksRecorder.java

@@ -0,0 +1,36 @@
+package io.quarkus.runtime;
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.RuntimeMXBean;
+import java.util.List;
+
+import org.jboss.logging.Logger;
+
+import io.quarkus.runtime.annotations.Recorder;
+
+@Recorder
+public class JVMChecksRecorder {
+
+    public void check() {
+        if (!isUnsafeMemoryAccessAllowed()) {
+            Logger.getLogger("JVM").warn(
+                    "Unsafe memory access is not going to be allowed in future versions of the JVM. Since Java 24, the JVM will print a warning on boot (most likely shown above), but several Quarkus extensions still require it. "
+                            +
+                            "There is currently no need to worry: please add the `--sun-misc-unsafe-memory-access=allow` JVM argument to avoid these warnings. "
+                            +
+                            "We are working with the maintainers of those libraries to get this resolved in future versions; when this is done, we will remove the need for this argument.");
+        }
+    }
+
+    public static boolean isUnsafeMemoryAccessAllowed() {
+        if (Runtime.version().feature() < 24) {
+            //Versions before Java 24 would not complain about the use of Unsafe.
+            //Also, setting `--sun-misc-unsafe-memory-access=allow` isn't possible (not a valid argument) before Java 24.
+            return true;
+        }
+        RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
+        List<String> arguments = runtimeMxBean.getInputArguments();
+        return arguments.contains("--sun-misc-unsafe-memory-access=allow");
+    }
+
+}