Proof of concept support for virtual threads using a mjar

build.gradle

@@ -1,16 +1,16 @@
 buildscript {
     ext {
         palantirGitVersionVersion = "${JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_11) ? '0.15.0' : '0.13.0'}"
-        kotlinVersion = "${project.hasProperty("edgeDepsTest") ? '1.8.20' : (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_16) ? '1.5.32' : '1.4.32')}"
+        kotlinVersion = "${project.hasProperty("edgeDepsTest") ? '1.8.20' : '1.6.20' }"
     }
 }
 
 plugins {
-    id 'net.ltgt.errorprone' version '3.0.1' apply false
+    id 'net.ltgt.errorprone' version '3.1.0' apply false
     id 'org.cadixdev.licenser' version '0.6.1'
     id 'com.palantir.git-version' version "${palantirGitVersionVersion}" apply false
     id 'io.github.gradle-nexus.publish-plugin' version '1.3.0'
-    id 'com.diffplug.spotless' version '6.18.0' apply false
+    id 'com.diffplug.spotless' version '6.25.0' apply false
     id 'com.github.nbaztec.coveralls-jacoco' version "1.2.15" apply false
 
     //    id 'org.jetbrains.kotlin.jvm' version '1.4.32'
@@ -61,7 +61,7 @@ ext {
     // test scoped
     // we don't upgrade to 1.3 and 1.4 because they require slf4j 2.x
     logbackVersion = project.hasProperty("edgeDepsTest") ? '1.3.5' : '1.2.11'
-    mockitoVersion = '5.2.0'
+    mockitoVersion = '5.11.0'
     junitVersion = '4.13.2'
 }
 

gradle/errorprone.gradle

@@ -5,7 +5,7 @@ subprojects {
     dependencies {
         errorproneJavac('com.google.errorprone:javac:9+181-r4173-1')
         if (JavaVersion.current().isJava11Compatible()) {
-            errorprone('com.google.errorprone:error_prone_core:2.18.0')
+            errorprone('com.google.errorprone:error_prone_core:2.26.0')
         } else {
             errorprone('com.google.errorprone:error_prone_core:2.10.0')
         }

gradle/java.gradle

@@ -5,9 +5,9 @@ subprojects {
     apply plugin: 'java-library'
 
     java {
-        // graal only supports java 8, 11, 16, 17
-        sourceCompatibility = project.hasProperty("edgeDepsTest") ? JavaVersion.VERSION_17 : JavaVersion.VERSION_1_8
-        targetCompatibility = project.hasProperty("edgeDepsTest") ? JavaVersion.VERSION_17 : JavaVersion.VERSION_1_8
+        // graal only supports java 8, 11, 16, 17, 21
+        sourceCompatibility = project.hasProperty("edgeDepsTest") ? JavaVersion.VERSION_21 : JavaVersion.VERSION_21
+        targetCompatibility = project.hasProperty("edgeDepsTest") ? JavaVersion.VERSION_21 : JavaVersion.VERSION_21
         withJavadocJar()
         withSourcesJar()
     }
@@ -24,10 +24,10 @@ subprojects {
     compileTestJava {
         options.encoding = 'UTF-8'
         options.compilerArgs << '-Xlint:none' << '-Xlint:deprecation' << '-Werror' << '-parameters'
-        if (JavaVersion.current().isJava9Compatible() && !project.hasProperty("edgeDepsTest")) {
-            // https://stackoverflow.com/a/43103115/525203
-            options.compilerArgs.addAll(['--release', '8'])
-        }
+//        if (JavaVersion.current().isJava9Compatible() && !project.hasProperty("edgeDepsTest")) {
+//            // https://stackoverflow.com/a/43103115/525203
+//            options.compilerArgs.addAll(['--release', '8'])
+//        }
     }
 
     javadoc {

gradle/linting.gradle

@@ -9,7 +9,7 @@ subprojects {
             target 'src/*/java/**/*.java'
             targetExclude '**/generated/*'
             targetExclude '**/.idea/**'
-            googleJavaFormat('1.16.0')
+            googleJavaFormat('1.17.0')
         }
 
         kotlin {

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
 networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

temporal-opentracing/src/main/java/io/temporal/opentracing/StandardTagNames.java

@@ -25,6 +25,7 @@ public class StandardTagNames {
   public static final String RUN_ID = "runId";
   public static final String PARENT_WORKFLOW_ID = "parentWorkflowId";
   public static final String PARENT_RUN_ID = "parentRunId";
+
   /**
    * @deprecated use {@link io.opentracing.tag.Tags#ERROR}
    */

temporal-sdk/build.gradle

@@ -28,6 +28,34 @@ dependencies {
     testImplementation group: 'ch.qos.logback', name: 'logback-classic', version: "${logbackVersion}"
 }
 
+if (JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_21)) {
+    sourceSets {
+        java21 {
+            java {
+                srcDirs = ['src/main/java21']
+            }
+        }
+    }
+
+    dependencies {
+        java21Implementation files(sourceSets.main.output.classesDirs) { builtBy compileJava }
+    }
+
+    compileJava21Java {
+        targetCompatibility = JavaVersion.VERSION_21
+        sourceCompatibility = JavaVersion.VERSION_21
+    }
+
+    jar {
+        into('META-INF/versions/21') {
+            from sourceSets.java21.output
+        }
+        manifest.attributes(
+                'Multi-Release': 'true'
+        )
+    }
+}
+
 task registerNamespace(type: JavaExec) {
     getMainClass().set('io.temporal.internal.docker.RegisterTestNamespace')
     classpath = sourceSets.test.runtimeClasspath

temporal-sdk/src/main/java/io/temporal/client/WorkflowClient.java

@@ -114,6 +114,7 @@ public interface WorkflowClient {
 
   /** Use this constant as a query type to get a workflow stack trace. */
   String QUERY_TYPE_STACK_TRACE = "__stack_trace";
+
   /** Replays workflow to the current state and returns empty result or error if replay failed. */
   String QUERY_TYPE_REPLAY_ONLY = "__replay_only";
 

temporal-sdk/src/main/java/io/temporal/internal/common/WorkflowExecutionHistory.java

@@ -45,6 +45,7 @@
 public class WorkflowExecutionHistory {
   protected static final String DEFAULT_WORKFLOW_ID = "workflow_id_in_replay";
   private static final Gson GSON_PRETTY_PRINTER = new GsonBuilder().setPrettyPrinting().create();
+
   // we stay on using the old API that uses a JsonParser instance instead of static methods
   // to give users a larger range of supported version
   @SuppressWarnings("deprecation")

temporal-sdk/src/main/java/io/temporal/internal/statemachines/LocalActivityCallback.java

@@ -39,6 +39,7 @@ public interface LocalActivityCallback
   class LocalActivityFailedException extends RuntimeException {
     private final @Nonnull Failure failure;
     private final int lastAttempt;
+
     /**
      * If this is not null, code that processes this exception will schedule a workflow timer to
      * continue retrying the execution

temporal-sdk/src/main/java/io/temporal/internal/statemachines/LocalActivityStateMachine.java

@@ -64,6 +64,7 @@ final class LocalActivityStateMachine
 
   private ExecuteLocalActivityParameters localActivityParameters;
   private final Functions.Func<Boolean> replaying;
+
   /** Accepts proposed current time. Returns accepted current time. */
   private final Functions.Func1<Long, Long> setCurrentTimeCallback;
 
@@ -74,6 +75,7 @@ final class LocalActivityStateMachine
 
   /** Workflow timestamp when the LA state machine is initialized */
   private final long workflowTimeMillisWhenStarted;
+
   /**
    * System.nanoTime result at the moment of LA state machine initialization. May be used to
    * calculate elapsed time

temporal-sdk/src/main/java/io/temporal/internal/statemachines/VersionStateMachine.java

@@ -45,6 +45,7 @@ final class VersionStateMachine {
   private final Functions.Proc1<StateMachine> stateMachineSink;
 
   @Nullable private Integer version;
+
   /**
    * This variable is used for replay only. When we replay, we look one workflow task ahead and
    * preload all version markers to be able to return from Workflow.getVersion called in the event
@@ -368,6 +369,7 @@ private VersionStateMachine(
     this.commandSink = Objects.requireNonNull(commandSink);
     this.stateMachineSink = stateMachineSink;
   }
+
   /**
    * Get the version for this state machine.
    *

temporal-sdk/src/main/java/io/temporal/internal/sync/CancellationScopeImpl.java

@@ -57,6 +57,7 @@ private static void popCurrent(CancellationScopeImpl expected) {
   private final Runnable runnable;
   private CancellationScopeImpl parent;
   private final Set<CancellationScopeImpl> children = new HashSet<>();
+
   /**
    * When disconnected scope has no parent and thus doesn't receive cancellation requests from it.
    */

temporal-sdk/src/main/java/io/temporal/internal/sync/POJOWorkflowImplementationFactory.java

@@ -85,9 +85,11 @@ public final class POJOWorkflowImplementationFactory implements ReplayWorkflowFa
   /** Key: workflow type name, Value: function that creates SyncWorkflowDefinition instance. */
   private final Map<String, Functions.Func1<WorkflowExecution, SyncWorkflowDefinition>>
       workflowDefinitions = Collections.synchronizedMap(new HashMap<>());
+
   /** Factories providing instances of workflow classes. */
   private final Map<Class<?>, Functions.Func<?>> workflowInstanceFactories =
       Collections.synchronizedMap(new HashMap<>());
+
   /** If present then it is called for any unknown workflow type. */
   private Functions.Func<? extends DynamicWorkflow> dynamicWorkflowImplementationFactory;
 

temporal-sdk/src/main/java/io/temporal/internal/task/ThreadConfigurator.java

@@ -0,0 +1,5 @@
+package io.temporal.internal.task;
+
+public interface ThreadConfigurator {
+  void configure(Thread t);
+}

temporal-sdk/src/main/java/io/temporal/internal/task/VirtualThreadDelegate.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2024 Temporal Technologies, Inc. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this material except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://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.temporal.internal.task;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadFactory;
+
+/**
+ * Internal delegate for virtual thread handling on JDK 21.
+ * This is a dummy version for reachability on JDK <21.
+ */
+public final class VirtualThreadDelegate {
+
+  public VirtualThreadDelegate() {
+    throw new UnsupportedOperationException("Virtual threads not supported on JDK <21");
+  }
+
+  public ThreadFactory virtualThreadFactory() {
+    throw new UnsupportedOperationException();
+  }
+
+  public ExecutorService newVirtualThreadExecutor(ThreadConfigurator configurator) {
+    throw new UnsupportedOperationException();
+  }
+}

temporal-sdk/src/main/java/io/temporal/internal/worker/LocalActivityResult.java

@@ -34,6 +34,7 @@ public final class LocalActivityResult {
   private final @Nullable RespondActivityTaskCompletedRequest executionCompleted;
   private final @Nullable ExecutionFailedResult executionFailed;
   private final @Nullable RespondActivityTaskCanceledRequest executionCanceled;
+
   /**
    * If present, it will cause an immediate WFT failure instead of providing LA result to the
    * workflow code.

temporal-sdk/src/main/java/io/temporal/payload/context/WorkflowSerializationContext.java

@@ -27,6 +27,7 @@
 public class WorkflowSerializationContext implements HasWorkflowSerializationContext {
   private final @Nonnull String namespace;
   private final @Nonnull String workflowId;
+
   // We can't currently reliably and consistency provide workflowType to the DataConverter.
   // 1. Signals and queries don't know workflowType when they are sent.
   // 2. WorkflowStub#getResult call is not aware of the workflowType, workflowType is an optional

temporal-sdk/src/main/java/io/temporal/worker/ActiveThreadReportingExecutor.java

@@ -22,6 +22,7 @@
 
 import com.uber.m3.tally.Scope;
 import io.temporal.internal.sync.WorkflowThreadExecutor;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -34,11 +35,11 @@
  * reasons. {@link ThreadPoolExecutor#getActiveCount()} take a pool-wide lock.
  */
 class ActiveThreadReportingExecutor implements WorkflowThreadExecutor {
-  private final ThreadPoolExecutor workflowThreadPool;
+  private final ExecutorService workflowThreadPool;
   private final Scope metricsScope;
   private final AtomicInteger tasksInFlight = new AtomicInteger();
 
-  ActiveThreadReportingExecutor(ThreadPoolExecutor workflowThreadPool, Scope metricsScope) {
+  ActiveThreadReportingExecutor(ExecutorService workflowThreadPool, Scope metricsScope) {
     this.workflowThreadPool = workflowThreadPool;
     this.metricsScope = metricsScope;
   }

temporal-sdk/src/main/java/io/temporal/worker/MetricsType.java

@@ -54,6 +54,7 @@ private MetricsType() {}
       TEMPORAL_METRICS_PREFIX + "workflow_task_schedule_to_start_latency";
   public static final String WORKFLOW_TASK_EXECUTION_LATENCY =
       TEMPORAL_METRICS_PREFIX + "workflow_task_execution_latency";
+
   /** Total latency of a workflow task which can include multiple forced decision tasks */
   public static final String WORKFLOW_TASK_EXECUTION_TOTAL_LATENCY =
       TEMPORAL_METRICS_PREFIX + "workflow_task_execution_total_latency";
@@ -64,6 +65,7 @@ private MetricsType() {}
   /** Workflow task failed, possibly failing workflow or reporting failure to the service. */
   public static final String WORKFLOW_TASK_EXECUTION_FAILURE_COUNTER =
       TEMPORAL_METRICS_PREFIX + "workflow_task_execution_failed";
+
   /**
    * Workflow task failed with unhandled exception without replying to the service.<br>
    * This typically happens when workflow task fails second time in a row.<br>
@@ -93,6 +95,7 @@ private MetricsType() {}
       TEMPORAL_METRICS_PREFIX + "activity_execution_failed";
   public static final String ACTIVITY_EXEC_CANCELLED_COUNTER =
       TEMPORAL_METRICS_PREFIX + "activity_execution_cancelled";
+
   /**
    * @deprecated use {@link #ACTIVITY_EXEC_CANCELLED_COUNTER}
    */
@@ -113,6 +116,7 @@ private MetricsType() {}
 
   public static final String LOCAL_ACTIVITY_EXEC_CANCELLED_COUNTER =
       TEMPORAL_METRICS_PREFIX + "local_activity_execution_cancelled";
+
   /**
    * @deprecated use {@link #LOCAL_ACTIVITY_EXEC_CANCELLED_COUNTER}
    */
@@ -122,6 +126,7 @@ private MetricsType() {}
 
   public static final String LOCAL_ACTIVITY_EXEC_FAILED_COUNTER =
       TEMPORAL_METRICS_PREFIX + "local_activity_execution_failed";
+
   /**
    * @deprecated use {@link #LOCAL_ACTIVITY_EXEC_FAILED_COUNTER}
    */
@@ -144,6 +149,7 @@ private MetricsType() {}
   public static final String STICKY_CACHE_HIT = TEMPORAL_METRICS_PREFIX + "sticky_cache_hit";
   // tagged with namespace, task_queue, worker_type, workflow_type
   public static final String STICKY_CACHE_MISS = TEMPORAL_METRICS_PREFIX + "sticky_cache_miss";
+
   // tagged with namespace, task_queue, worker_type, workflow_type
   @Deprecated
   // This metric in its current form is useless, it's not possible for users to interpret it for any
@@ -161,6 +167,7 @@ private MetricsType() {}
   //  Otherwise deprecate it everywhere and remove from docs.
   public static final String STICKY_CACHE_TOTAL_FORCED_EVICTION =
       TEMPORAL_METRICS_PREFIX + "sticky_cache_total_forced_eviction";
+
   // tagged with namespace, task_queue, worker_type, workflow_type
   public static final String STICKY_CACHE_THREAD_FORCED_EVICTION =
       TEMPORAL_METRICS_PREFIX + "sticky_cache_thread_forced_eviction";