Experiment with fully virtual VirtualThreadPool

jetty-core/jetty-server/src/main/config/etc/jetty-threadpool-all-virtual.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "https://www.eclipse.org/jetty/configure_10_0.dtd">
+
+<Configure>
+  <New id="threadPool" class="org.eclipse.jetty.util.thread.VirtualThreadPool">
+    <Set name="name" property="jetty.threadPool.namePrefix" />
+  </New>
+
+  <Call class="org.slf4j.LoggerFactory" name="getLogger">
+    <Arg>org.eclipse.jetty</Arg>
+    <Call name="info">
+      <Arg>All Virtual threads are enabled.</Arg>
+    </Call>
+  </Call>
+</Configure>

jetty-core/jetty-server/src/main/config/modules/threadpool-all-virtual.mod

@@ -0,0 +1,19 @@
+[description]
+Enables and configures the Server ThreadPool with support for virtual threads to be used for all threads.
+There is some risk of CPU pinning with this configuration.  Only supported in Java 21 or later.
+
+[depends]
+logging
+
+[provides]
+threadpool
+
+[xml]
+etc/jetty-threadpool-all-virtual.xml
+
+[ini-template]
+# tag::documentation[]
+## Platform threads name prefix.
+#jetty.threadPool.namePrefix=vtp<hashCode>
+
+# end::documentation[]

jetty-core/jetty-server/src/main/config/modules/threadpool-virtual.mod

@@ -1,5 +1,6 @@
 [description]
-Enables and configures the Server ThreadPool with support for virtual threads in Java 21 or later.
+Enables and configures the Server ThreadPool with support for virtual threads to be used for blocking tasks.
+Only supported in Java 21 or later.
 
 [depends]
 logging

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/VirtualThreads.java

@@ -32,21 +32,9 @@
 public class VirtualThreads
 {
     private static final Logger LOG = LoggerFactory.getLogger(VirtualThreads.class);
-    private static final Executor executor = probeVirtualThreadExecutor();
+    private static final ThreadFactoryExecutor executor = getNamedVirtualThreadFactoryExecutor(null);
     private static final Method isVirtualThread = probeIsVirtualThread();
 
-    private static Executor probeVirtualThreadExecutor()
-    {
-        try
-        {
-            return (Executor)Executors.class.getMethod("newVirtualThreadPerTaskExecutor").invoke(null);
-        }
-        catch (Throwable x)
-        {
-            return null;
-        }
-    }
-
     private static Method probeIsVirtualThread()
     {
         try
@@ -126,14 +114,41 @@ public static boolean isVirtualThread()
      * @return a virtual threads {@code Executor} that will name the virtual threads according to the provided name prefix.
      */
     public static Executor getNamedVirtualThreadsExecutor(String namePrefix)
+    {
+        return getNamedVirtualThreadFactoryExecutor(namePrefix);
+    }
+
+    /**
+     * Get a virtual threads {@code Executor} that names the virtual threads according to the provided name prefix.
+     * While named virtual threads enable observability they do also incur a minor performance penalty.
+     *
+     * @param namePrefix the prefix to use for the name of the virtual threads
+     * @return a virtual threads {@code Executor} that will name the virtual threads according to the provided name prefix.
+     */
+    public static ThreadFactoryExecutor getNamedVirtualThreadFactoryExecutor(String namePrefix)
     {
         try
         {
             Class<?> builderClass = Class.forName("java.lang.Thread$Builder");
             Object threadBuilder = Thread.class.getMethod("ofVirtual").invoke(null);
-            threadBuilder = builderClass.getMethod("name", String.class, long.class).invoke(threadBuilder, namePrefix, 0L);
+            if (StringUtil.isNotBlank(namePrefix))
+                threadBuilder = builderClass.getMethod("name", String.class, long.class).invoke(threadBuilder, namePrefix, 0L);
             ThreadFactory factory = (ThreadFactory)builderClass.getMethod("factory").invoke(threadBuilder);
-            return (Executor)Executors.class.getMethod("newThreadPerTaskExecutor", ThreadFactory.class).invoke(null, factory);
+            Executor executor =  (Executor)Executors.class.getMethod("newThreadPerTaskExecutor", ThreadFactory.class).invoke(null, factory);
+            return new ThreadFactoryExecutor()
+            {
+                @Override
+                public void execute(Runnable command)
+                {
+                    executor.execute(command);
+                }
+
+                @Override
+                public Thread newThread(Runnable r)
+                {
+                    return factory.newThread(r);
+                }
+            };
         }
         catch (Throwable x)
         {
@@ -150,6 +165,15 @@ public static Executor getDefaultVirtualThreadsExecutor()
         return executor;
     }
 
+    /**
+     * Get a default virtual thread per task {@code Executor}.
+     * @return a default virtual thread per task {@code Executor}
+     */
+    public static ThreadFactoryExecutor getDefaultVirtualThreadFactoryExecutor()
+    {
+        return executor;
+    }
+
     /**
      * @param executor the {@code Executor} to obtain a virtual threads {@code Executor} from
      * @return a virtual threads {@code Executor} obtained from the given {@code Executor}
@@ -233,4 +257,7 @@ default void setUseVirtualThreads(boolean useVirtualThreads)
     private VirtualThreads()
     {
     }
+
+    public interface ThreadFactoryExecutor extends ThreadFactory, Executor
+    {}
 }

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/thread/QueuedThreadPool.java

@@ -449,7 +449,7 @@ public void setReservedThreads(int reservedThreads)
     }
 
     /**
-     * @return the name of the this thread pool
+     * @return the name of this thread pool
      */
     @ManagedAttribute("name of the thread pool")
     public String getName()
@@ -460,7 +460,7 @@ public String getName()
     /**
      * <p>Sets the name of this thread pool, used as a prefix for the thread names.</p>
      *
-     * @param name the name of the this thread pool
+     * @param name the name of this thread pool
      */
     public void setName(String name)
     {
@@ -835,7 +835,7 @@ public void join() throws InterruptedException
 
         while (isStopping())
         {
-            Thread.sleep(1);
+            Thread.onSpinWait();
         }
     }