Virtual threads metrics

build.gradle

@@ -343,7 +343,7 @@ subprojects {
 
             check.dependsOn("testModules")
 
-            if (!(project.name in ['micrometer-test-aspectj-ltw', 'micrometer-test-aspectj-ctw'])) { // add projects here that do not exist in the previous minor so should be excluded from japicmp
+            if (!(project.name in ['micrometer-test-aspectj-ltw', 'micrometer-test-aspectj-ctw', 'micrometer-java21'])) { // add projects here that do not exist in the previous minor so should be excluded from japicmp
                 apply plugin: 'me.champeau.gradle.japicmp'
                 apply plugin: 'de.undercouch.download'
 

micrometer-java21/build.gradle

@@ -0,0 +1,23 @@
+description 'Micrometer core classes that require Java 21'
+
+// skip this module when building with jdk <21
+if (!javaLanguageVersion.canCompileOrRun(21)) {
+    project.tasks.configureEach { task -> task.enabled = false }
+}
+
+dependencies {
+    api project(":micrometer-core")
+
+    testImplementation 'org.junit.jupiter:junit-jupiter'
+    testImplementation 'org.awaitility:awaitility'
+}
+
+java {
+    targetCompatibility = 21
+}
+
+tasks.withType(JavaCompile).configureEach {
+    sourceCompatibility = JavaVersion.VERSION_21
+    targetCompatibility = JavaVersion.VERSION_21
+    options.release = 21
+}

micrometer-java21/src/main/java/io/micrometer/java21/instrument/binder/jfr/JfrVirtualThreadEventMetrics.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2024 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micrometer.java21.instrument.binder.jfr;
+
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.Timer;
+import io.micrometer.core.instrument.binder.MeterBinder;
+import jdk.jfr.consumer.RecordingStream;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Objects;
+
+import static java.util.Collections.emptyList;
+
+public class JfrVirtualThreadEventMetrics implements MeterBinder, Closeable {
+
+    private static final String PINNED_EVENT = "jdk.VirtualThreadPinned";
+
+    private static final String SUBMIT_FAILED_EVENT = "jdk.VirtualThreadSubmitFailed";
+
+    private final RecordingSettings settings;
+
+    private final Iterable<Tag> tags;
+
+    private boolean started = false;
+
+    private RecordingStream recordingStream;
+
+    public JfrVirtualThreadEventMetrics() {
+        this(new RecordingSettings(), emptyList());
+    }
+
+    public JfrVirtualThreadEventMetrics(Iterable<Tag> tags) {
+        this(new RecordingSettings(), tags);
+    }
+
+    public JfrVirtualThreadEventMetrics(RecordingSettings settings, Iterable<Tag> tags) {
+        this.settings = settings;
+        this.tags = tags;
+    }
+
+    @Override
+    public void bindTo(MeterRegistry registry) {
+        if (started) {
+            return;
+        }
+
+        started = true;
+        recordingStream = createRecordingStream(settings);
+
+        final Timer pinnedTimer = Timer.builder("jvm.virtual.thread.pinned")
+            .tags(tags)
+            .description("The duration of virtual threads that were pinned to a physical thread")
+            .register(registry);
+
+        final Counter submitFailedCounter = Counter.builder("jvm.virtual.thread.submit.failed")
+            .tags(tags)
+            .description("The number of virtual thread submissions that failed")
+            .register(registry);
+
+        recordingStream.onEvent(PINNED_EVENT, event -> pinnedTimer.record(event.getDuration()));
+        recordingStream.onEvent(SUBMIT_FAILED_EVENT, event -> submitFailedCounter.increment());
+    }
+
+    protected RecordingStream createRecordingStream(RecordingSettings settings) {
+        final RecordingStream recordingStream = new RecordingStream();
+        recordingStream.enable(PINNED_EVENT).withThreshold(settings.pinnedThreshold);
+        recordingStream.enable(SUBMIT_FAILED_EVENT);
+        recordingStream.setMaxAge(settings.maxAge);
+        recordingStream.setMaxSize(settings.maxSizeBytes);
+        recordingStream.startAsync();
+        return recordingStream;
+    }
+
+    @Override
+    public void close() throws IOException {
+        if (started) {
+            recordingStream.close();
+        }
+    }
+
+    public record RecordingSettings(Duration maxAge, long maxSizeBytes, Duration pinnedThreshold) {
+        public RecordingSettings {
+            Objects.requireNonNull(maxAge, "maxAge parameter must not be null");
+            Objects.requireNonNull(pinnedThreshold, "pinnedThreshold must not be null");
+            if (maxSizeBytes < 0) {
+                throw new IllegalArgumentException("maxSizeBytes must be positive");
+            }
+        }
+
+        public RecordingSettings() {
+            this(Duration.ofSeconds(5), 10L * 1024 * 1024, Duration.ofMillis(20));
+        }
+    }
+
+}

micrometer-java21/src/main/java/io/micrometer/java21/instrument/binder/jfr/package-info.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2024 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Instrumentation of JDK classes.
+ */
+@NonNullApi
+@NonNullFields
+package io.micrometer.java21.instrument.binder.jfr;
+
+import io.micrometer.common.lang.NonNullApi;
+import io.micrometer.common.lang.NonNullFields;

micrometer-java21/src/test/java/io/micrometer/java21/instrument/binder/jfr/JfrVirtualThreadEventMetricsTests.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2022 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micrometer.java21.instrument.binder.jfr;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tags;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.time.Duration;
+
+import static org.awaitility.Awaitility.await;
+
+class JfrVirtualThreadEventMetricsTests {
+
+    private static final Tags USER_TAGS = Tags.of("k", "v");
+
+    private MeterRegistry registry;
+
+    private JfrVirtualThreadEventMetrics jfrMetrics;
+
+    @BeforeEach
+    void setup() {
+        registry = new SimpleMeterRegistry();
+        jfrMetrics = new JfrVirtualThreadEventMetrics(USER_TAGS);
+        jfrMetrics.bindTo(registry);
+    }
+
+    @Test
+    void registerPinnedEvent() throws Exception {
+        Thread.ofVirtual().name("vt-test").start(() -> {
+            synchronized (this) {
+                sleep(Duration.ofMillis(100));
+            }
+        }).join();
+
+        await().atMost(Duration.ofSeconds(2))
+            .until(() -> registry.get("jvm.virtual.thread.pinned").tags(USER_TAGS).timer().count() == 1);
+    }
+
+    private void sleep(Duration duration) {
+        try {
+            Thread.sleep(duration);
+        }
+        catch (InterruptedException ignored) {
+        }
+    }
+
+    @AfterEach
+    void cleanup() throws IOException {
+        jfrMetrics.close();
+    }
+
+}

settings.gradle

@@ -47,6 +47,7 @@ include 'concurrency-tests'
 include 'micrometer-bom'
 include 'micrometer-jakarta9'
 include 'micrometer-java11'
+include 'micrometer-java21'
 include 'micrometer-jetty11'
 include 'micrometer-jetty12'
 include 'micrometer-osgi-test'