add support for Virtual threads

Signed-off-by: Ceki Gulcu <ceki@qos.ch>

logback-core/src/main/java/ch/qos/logback/core/Context.java

@@ -132,6 +132,13 @@ public interface Context extends PropertyContainer {
      */
     ExecutorService getExecutorService();
 
+    /**
+     * Return an alternate {@link ExecutorService} used for one task per thread execution.
+     * @return ExecutorService
+     */
+    default ExecutorService getAlternateExecutorService() {
+        return getExecutorService();
+    }
 
     /**
      * Register a component that participates in the context's life cycle.

logback-core/src/main/java/ch/qos/logback/core/ContextBase.java

@@ -54,6 +54,8 @@ public class ContextBase implements Context, LifeCycle {
     private ScheduledExecutorService scheduledExecutorService;
 
     private ThreadPoolExecutor threadPoolExecutor;
+    private ExecutorService alternateExecutorService;
+
 
     protected List<ScheduledFuture<?>> scheduledFutures = new ArrayList<ScheduledFuture<?>>(1);
     private LifeCycleManager lifeCycleManager;
@@ -225,8 +227,15 @@ public synchronized ExecutorService getExecutorService() {
         return threadPoolExecutor;
     }
 
-
     @Override
+    public synchronized ExecutorService getAlternateExecutorService() {
+        if(alternateExecutorService == null) {
+            alternateExecutorService = ExecutorServiceUtil.newAlternateThreadPoolExecutor();
+        }
+        return alternateExecutorService;
+    }
+
+        @Override
     public synchronized ScheduledExecutorService getScheduledExecutorService() {
         if (scheduledExecutorService == null) {
             scheduledExecutorService = ExecutorServiceUtil.newScheduledExecutorService();

logback-core/src/main/java/ch/qos/logback/core/CoreConstants.java

@@ -29,13 +29,14 @@ public class CoreConstants {
      */
     public static final int CORE_POOL_SIZE = 0;
 
-    public static final int SCHEDULED_EXECUTOR_POOL_SIZE = 2;
+    // In Java 21 and later the actual threads are assumed to be virtual
+    public static final int SCHEDULED_EXECUTOR_POOL_SIZE = 4;
 
     /**
      * Maximum number of threads to allow in a context's executor service.
      */
-    // if you need a different MAX_POOL_SIZE, please file create a jira issue
-    // asking to make MAX_POOL_SIZE a parameter.
+    // if you need a different MAX_POOL_SIZE, please file create a github issue
+    // asking for a larger MAX_POOL_SIZE parameter.
     public static final int MAX_POOL_SIZE = 32;
 
     // Note that the line.separator property can be looked up even by

logback-core/src/main/java/ch/qos/logback/core/rolling/helper/TimeBasedArchiveRemover.java

@@ -47,6 +47,18 @@ public TimeBasedArchiveRemover(FileNamePattern fileNamePattern, RollingCalendar
 
     int callCount = 0;
 
+    public Future<?> cleanAsynchronously(Instant now) {
+        ArhiveRemoverRunnable runnable = new ArhiveRemoverRunnable(now);
+        ExecutorService alternateExecutorService = context.getAlternateExecutorService();
+        Future<?> future = alternateExecutorService.submit(runnable);
+        return future;
+    }
+
+    /**
+     * Called from the cleaning thread.
+     *
+     * @param now
+     */
     @Override
     public void clean(Instant now) {
 
@@ -233,12 +245,7 @@ public String toString() {
         return "c.q.l.core.rolling.helper.TimeBasedArchiveRemover";
     }
 
-    public Future<?> cleanAsynchronously(Instant now) {
-        ArhiveRemoverRunnable runnable = new ArhiveRemoverRunnable(now);
-        ExecutorService executorService = context.getExecutorService();
-        Future<?> future = executorService.submit(runnable);
-        return future;
-    }
+
 
     public class ArhiveRemoverRunnable implements Runnable {
         Instant now;

logback-core/src/main/java/ch/qos/logback/core/util/EnvUtil.java

@@ -108,6 +108,14 @@ static public boolean isJDK18OrHigher() {
         return isJDK_N_OrHigher(18);
     }
 
+    /**
+     * @since logback 1.3.12/1.4.12
+     * @return true if runtime JDK is version 21 or higher
+     */
+    static public boolean isJDK21OrHigher() {
+        return isJDK_N_OrHigher(21);
+    }
+
     static public boolean isJaninoAvailable() {
         ClassLoader classLoader = EnvUtil.class.getClassLoader();
         try {

logback-core/src/main/java/ch/qos/logback/core/util/ExecutorServiceUtil.java

@@ -13,6 +13,8 @@
  */
 package ch.qos.logback.core.util;
 
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
@@ -33,11 +35,39 @@
  */
 public class ExecutorServiceUtil {
 
-    private static final ThreadFactory THREAD_FACTORY = new ThreadFactory() {
+    static private final String  NEW_VIRTUAL_TPT_METHOD_NAME = "newVirtualThreadPerTaskExecutor";
+
+    private static final ThreadFactory THREAD_FACTORY_FOR_SCHEDULED_EXECUTION_SERVICE = new ThreadFactory() {
 
-        private final ThreadFactory defaultFactory = Executors.defaultThreadFactory();
         private final AtomicInteger threadNumber = new AtomicInteger(1);
 
+
+        private final ThreadFactory defaultFactory = makeThreadFactory();
+
+        /**
+         * A thread factory which may be a virtual thread factory if available.
+         *
+         * @return
+         */
+        private ThreadFactory makeThreadFactory() {
+            if(EnvUtil.isJDK21OrHigher()) {
+                try {
+                    Method ofVirtualMethod = Thread.class.getMethod("ofVirtual");
+                    Object threadBuilderOfVirtual = ofVirtualMethod.invoke(null);
+                    Method factoryMethod = threadBuilderOfVirtual.getClass().getMethod("factory");
+                    System.out.println("virtual THREAD FACTORY");
+                    return (ThreadFactory) factoryMethod.invoke(threadBuilderOfVirtual);
+                } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
+                    return Executors.defaultThreadFactory();
+                }
+
+            } else {
+                System.out.println("default THREAD FACTORY");
+                return Executors.defaultThreadFactory();
+            }
+        }
+
+        @Override
         public Thread newThread(Runnable r) {
             Thread thread = defaultFactory.newThread(r);
             if (!thread.isDaemon()) {
@@ -49,7 +79,8 @@ public Thread newThread(Runnable r) {
     };
 
     static public ScheduledExecutorService newScheduledExecutorService() {
-        return new ScheduledThreadPoolExecutor(CoreConstants.SCHEDULED_EXECUTOR_POOL_SIZE, THREAD_FACTORY);
+        return new ScheduledThreadPoolExecutor(CoreConstants.SCHEDULED_EXECUTOR_POOL_SIZE,
+                THREAD_FACTORY_FOR_SCHEDULED_EXECUTION_SERVICE);
     }
 
     /**
@@ -68,7 +99,7 @@ static public ExecutorService newExecutorService() {
      */
     static public ThreadPoolExecutor newThreadPoolExecutor() {
         return new ThreadPoolExecutor(CoreConstants.CORE_POOL_SIZE, CoreConstants.MAX_POOL_SIZE, 0L,
-                TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>(), THREAD_FACTORY);
+                TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>(), THREAD_FACTORY_FOR_SCHEDULED_EXECUTION_SERVICE);
     }
 
     /**
@@ -83,4 +114,23 @@ static public void shutdown(ExecutorService executorService) {
         }
     }
 
+    /**
+     * An alternate implementation of {@linl #newThreadPoolExecutor} which returns a virtual thread per task executor when
+     * available.
+     *
+     * @since 1.3.12/1.4.12
+     */
+    static public ExecutorService newAlternateThreadPoolExecutor() {
+
+        if(EnvUtil.isJDK21OrHigher()) {
+            try {
+                Method newVirtualTPTMethod = Executors.class.getMethod(NEW_VIRTUAL_TPT_METHOD_NAME);
+                return (ExecutorService) newVirtualTPTMethod.invoke(null);
+            } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
+                return newThreadPoolExecutor();
+            }
+        } else {
+            return newThreadPoolExecutor();
+        }
+    }
 }

logback-core/src/test/java/ch/qos/logback/core/rolling/TimeBasedRollingWithArchiveRemoval_Test.java

@@ -22,7 +22,6 @@
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.ZonedDateTime;
-import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.Collections;
@@ -33,10 +32,8 @@
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.time.temporal.ChronoUnit;
 
-//import org.joda.time.DateTimeZone;
-//import org.joda.time.Days;
-//import org.joda.time.LocalDate;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;

pom.xml

@@ -49,11 +49,13 @@
 
   <properties>
     <!-- yyyy-MM-dd'T'HH:mm:ss'Z' -->
-    <project.build.outputTimestamp>2023-08-09T19:41:28Z</project.build.outputTimestamp>    
+    <project.build.outputTimestamp>2023-08-09T19:41:28Z</project.build.outputTimestamp>
+
+    <!-- minimal JDK version at runtime -->
     <jdk.version>11</jdk.version>
     <maven.compiler.release>${jdk.version}</maven.compiler.release>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <junit.version>4.13.1</junit.version>
+
     <junit-jupiter-api.version>5.9.1</junit-jupiter-api.version>
     <junit-vintage-engine.version>5.9.1</junit-vintage-engine.version>
     <junit-jupiter-params.version>5.9.1</junit-jupiter-params.version>
@@ -380,6 +382,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
+
         <configuration>
           <release>${jdk.version}</release>
         </configuration>