Adjust JFR checks for J9

Author: jbachorik

dd-java-agent/agent-profiling/profiling-uploader/src/main/java/com/datadog/profiling/uploader/util/JfrCliHelper.java

@@ -2,6 +2,7 @@
 
 import static datadog.trace.util.AgentThreadFactory.AgentThread.PROFILER_HTTP_DISPATCHER;
 
+import datadog.trace.api.Platform;
 import datadog.trace.api.profiling.RecordingData;
 import datadog.trace.relocate.api.IOLogger;
 import datadog.trace.util.AgentThreadFactory;
@@ -44,7 +45,7 @@ public static void invokeOn(final RecordingData data, final IOLogger ioLogger) {
     File tmp = null;
     try {
       Path jfr = Paths.get(System.getProperty("java.home"), "bin", "jfr");
-      if (!Files.exists(jfr)) {
+      if (Platform.isJ9() || !Files.exists(jfr)) {
         ioLogger.error("Failed to gather information on recording, can't find `jfr`");
         return;
       }

dd-java-agent/agent-profiling/profiling-uploader/src/test/java/com/datadog/profiling/uploader/ProfileUploaderTest.java

@@ -42,6 +42,7 @@
 import datadog.common.version.VersionInfo;
 import datadog.trace.api.Config;
 import datadog.trace.api.DDTags;
+import datadog.trace.api.Platform;
 import datadog.trace.api.profiling.ProfilingSnapshot;
 import datadog.trace.api.profiling.RecordingData;
 import datadog.trace.api.profiling.RecordingInputStream;
@@ -561,7 +562,10 @@ public void test413Response() throws Exception {
 
     verify(recording).release();
 
-    if (Files.exists(Paths.get(System.getProperty("java.home"), "bin", "jfr"))) {
+    // J9 has 'almost' implemented JFR, but not really
+    // we need to skip this part for J9
+    if (!Platform.isJ9()
+        && Files.exists(Paths.get(System.getProperty("java.home"), "bin", "jfr"))) {
       verify(ioLogger)
           .error(
               eq("Failed to upload profile, it's too big. Dumping information about the profile"));

dd-java-agent/agent-profiling/profiling-uploader/src/test/java/com/datadog/profiling/uploader/util/JfrCliHelperTest.java

@@ -9,6 +9,7 @@
 import static org.mockito.Mockito.when;
 import static org.mockito.Mockito.withSettings;
 
+import datadog.trace.api.Platform;
 import datadog.trace.api.profiling.RecordingData;
 import datadog.trace.api.profiling.RecordingInputStream;
 import datadog.trace.relocate.api.IOLogger;
@@ -24,6 +25,7 @@
 import java.util.Set;
 import java.util.zip.GZIPOutputStream;
 import org.apache.commons.io.IOUtils;
+import org.junit.jupiter.api.Assumptions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
@@ -44,6 +46,9 @@ public class JfrCliHelperTest {
 
   @Test
   public void testInvokeOn() throws Exception {
+    // J9 may have 'jfr' command present but it requires additional setup
+    // Currently we don't support J9 JFR so we can safely skip this test
+    Assumptions.assumeFalse(Platform.isJ9());
     final RecordingData recording = mockRecordingData();
 
     JfrCliHelper.invokeOn(recording, ioLogger);

dd-java-agent/agent-profiling/src/main/java/com/datadog/profiling/agent/CompositeController.java

@@ -153,8 +153,11 @@ public static Controller build(ConfigProvider provider, ControllerContext contex
       }
       if (!isOracleJDK8) {
         try {
-          Class.forName("jdk.jfr.Event");
-          controllers.add(OpenJdkController.instance(provider));
+          if (Platform.hasJfr()) {
+            controllers.add(OpenJdkController.instance(provider));
+          } else {
+            log.debug("JFR is not available on this platform");
+          }
         } catch (Throwable ignored) {
           log.debug("Failed to load openjdk profiler", ignored);
         }

dd-java-agent/testing/src/test/groovy/AgentTestRunnerTest.groovy

@@ -3,6 +3,7 @@ import datadog.trace.agent.test.AgentTestRunner
 import datadog.trace.agent.test.SpockRunner
 import datadog.trace.agent.test.utils.ClasspathUtils
 import datadog.trace.api.GlobalTracer
+import datadog.trace.api.Platform
 import datadog.trace.bootstrap.Constants
 import datadog.trace.bootstrap.instrumentation.api.AgentScope
 import datadog.trace.bootstrap.instrumentation.api.AgentSpan
@@ -180,11 +181,6 @@ class AgentTestRunnerTest extends AgentTestRunner {
   }
 
   boolean isJFRSupported() {
-    try {
-      Class.forName("jdk.jfr.Recording")
-      return true
-    } catch (Throwable e) {
-      return false
-    }
+    return Platform.hasJfr()
   }
 }

internal-api/src/main/java/datadog/trace/api/Platform.java

@@ -41,8 +41,10 @@ private static boolean checkForJfr() {
        * enhanced.
        * Need this custom check because ClassLoaderMatchers.hasClassNamed() does not support bootstrap class loader yet.
        * Note: the downside of this is that we load some JFR classes at startup.
+       * Note: as of version 0.49.0 of J9 the JVM contains JFR classes, but it is not fully functional
        */
-      return ClassLoader.getSystemClassLoader().getResource("jdk/jfr/Event.class") != null;
+      return !isJ9()
+          && ClassLoader.getSystemClassLoader().getResource("jdk/jfr/Event.class") != null;
     } catch (Throwable e) {
       return false;
     }