#624: Use virtual threads to model test users

ant-scripts/test.xml

@@ -315,6 +315,7 @@
             <jvmarg value="--add-opens=java.base/java.util=ALL-UNNAMED" />
             <jvmarg value="--add-opens=java.base/java.util.concurrent=ALL-UNNAMED" />
             <jvmarg value="--add-opens=java.base/java.util.regex=ALL-UNNAMED" />
+            <jvmarg value="--add-opens=java.base/java.util.stream=ALL-UNNAMED" />
             <jvmarg value="--add-opens=java.base/java.io=ALL-UNNAMED" />
             <jvmarg value="--add-opens=java.base/sun.nio.fs=ALL-UNNAMED" />
 

samples/testsuite-performance/config/default.properties

@@ -428,6 +428,9 @@ com.xceptance.xlt.maximumTransactionRunTime = 900000
 ## Useful in case of severe server errors, etc.
 com.xceptance.xlt.maxErrors = 1000
 
+## Whether to use virtual threads instead of platform threads (default: false).
+#com.xceptance.xlt.virtualThreads.enabled = false
+
 
 ################################################################################
 #

samples/testsuite-posters/config/default.properties

@@ -428,6 +428,9 @@ com.xceptance.xlt.maximumTransactionRunTime = 900000
 ## Useful in case of severe server errors, etc.
 com.xceptance.xlt.maxErrors = 1000
 
+## Whether to use virtual threads instead of platform threads (default: false).
+#com.xceptance.xlt.virtualThreads.enabled = false
+
 
 ################################################################################
 #

samples/testsuite-showcases/config/default.properties

@@ -428,6 +428,9 @@ com.xceptance.xlt.maximumTransactionRunTime = 900000
 ## Useful in case of severe server errors, etc.
 com.xceptance.xlt.maxErrors = 1000
 
+## Whether to use virtual threads instead of platform threads (default: false).
+#com.xceptance.xlt.virtualThreads.enabled = false
+
 
 ################################################################################
 #

samples/testsuite-template/config/default.properties

@@ -428,6 +428,9 @@ com.xceptance.xlt.maximumTransactionRunTime = 900000
 ## Useful in case of severe server errors, etc.
 com.xceptance.xlt.maxErrors = 1000
 
+## Whether to use virtual threads instead of platform threads (default: false).
+#com.xceptance.xlt.virtualThreads.enabled = false
+
 
 ################################################################################
 #

samples/testsuite-xlt/config/default.properties

@@ -428,6 +428,9 @@ com.xceptance.xlt.maximumTransactionRunTime = 900000
 ## Useful in case of severe server errors, etc.
 com.xceptance.xlt.maxErrors = 1000
 
+## Whether to use virtual threads instead of platform threads (default: false).
+#com.xceptance.xlt.virtualThreads.enabled = false
+
 
 ################################################################################
 #

src/main/java/com/xceptance/common/util/Holder.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2005-2025 Xceptance Software Technologies GmbH
+ *
+ * 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
+ *
+ *     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 com.xceptance.common.util;
+
+/**
+ * Simple Holder class that holds a value. Use this class to mimic a mutable reference.
+ */
+public class Holder<T>
+{
+    /**
+     * The value.
+     */
+    private T value;
+
+    /**
+     * Creates a new Holder instance and initializes it with a <code>null</code> value.
+     */
+    public Holder()
+    {
+        this(null);
+    }
+
+    /**
+     * Creates a new Holder instance and initializes it with the given value.
+     * 
+     * @param value
+     *            the initial value of the holder
+     */
+    public Holder(final T value)
+    {
+        this.value = value;
+    }
+
+    /**
+     * Returns the current value.
+     * 
+     * @return the value
+     */
+    public T get()
+    {
+        return value;
+    }
+
+    /**
+     * Sets the new value.
+     * 
+     * @param value
+     *            the new value
+     */
+    public void set(T value)
+    {
+        this.value = value;
+    }
+
+    /**
+     * Removes the current value.
+     * 
+     * @return the value just removed
+     */
+    public T remove()
+    {
+        final T oldValue = value;
+        value = null;
+
+        return oldValue;
+    }
+}

src/main/java/com/xceptance/xlt/agent/LoadTest.java

@@ -24,6 +24,7 @@
 import com.xceptance.xlt.agentcontroller.TestUserConfiguration;
 import com.xceptance.xlt.api.util.XltProperties;
 import com.xceptance.xlt.common.XltConstants;
+import com.xceptance.xlt.engine.XltThreadFactory;
 
 /**
  * Class responsible for running a load test.
@@ -37,17 +38,28 @@ public class LoadTest
      */
     private static final long DEFAULT_GRACE_PERIOD = 30 * 1000;
 
+    /**
+     * The thread factory that creates either virtual threads or platform threads for the {@link LoadTestRunner}
+     * instances.
+     */
+    private static final XltThreadFactory xltThreadFactory;
+
     /**
      * The configured time period [ms] to wait for threads to finish voluntarily before quitting the JVM.
      */
     private static final long gracePeriod;
 
     static
     {
-        final long v = XltProperties.getInstance().getProperty(XltConstants.XLT_PACKAGE_PATH + ".hangingUsersGracePeriod",
-                                                               DEFAULT_GRACE_PERIOD);
+        final XltProperties props = XltProperties.getInstance();
 
+        // grace period
+        final long v = props.getProperty(XltConstants.XLT_PACKAGE_PATH + ".hangingUsersGracePeriod", DEFAULT_GRACE_PERIOD);
         gracePeriod = (v < 0) ? DEFAULT_GRACE_PERIOD : v;
+
+        // thread factory
+        final boolean useVirtualThreads = props.getProperty(XltConstants.PROP_VIRTUAL_THREADS_ENABLED, false);
+        xltThreadFactory = new XltThreadFactory(useVirtualThreads, false);
     }
 
     /**
@@ -85,8 +97,7 @@ public void run()
             final AbstractExecutionTimer timer = ExecutionTimerFactory.createTimer(config);
 
             // create runner for configuration
-            final LoadTestRunner runner = new LoadTestRunner(config, agentInfo, timer);
-            runner.setDaemon(true);
+            final LoadTestRunner runner = new LoadTestRunner(config, agentInfo, timer, xltThreadFactory);
 
             // add runner to list of known runners
             testRunners.add(runner);

src/main/java/com/xceptance/xlt/agent/LoadTestRunner.java

@@ -30,6 +30,7 @@
 import com.xceptance.xlt.api.engine.GlobalClock;
 import com.xceptance.xlt.engine.DataManagerImpl;
 import com.xceptance.xlt.engine.SessionImpl;
+import com.xceptance.xlt.engine.XltThreadFactory;
 import com.xceptance.xlt.engine.util.TimerUtils;
 
 /**
@@ -40,7 +41,7 @@
  *
  * @author Jörg Werner (Xceptance Software Technologies GmbH)
  */
-public class LoadTestRunner extends Thread
+public class LoadTestRunner
 {
     /**
      * Class logger instance.
@@ -72,6 +73,11 @@ public class LoadTestRunner extends Thread
      */
     private volatile boolean aborted;
 
+    /**
+     * The main thread of this runner.
+     */
+    private final Thread thread;
+
     /**
      * Creates a new LoadTestRunner object for the given load test configuration. Typically, multiple runners are
      * started for one test case configuration, so the number of the current runner is passed as well.
@@ -82,19 +88,49 @@ public class LoadTestRunner extends Thread
      *            load test agent information
      * @param timer
      *            the execution timer that controls this load test runner
+     * @param xltThreadFactory
+     *            the thread factory to create the worker thread
      */
-    public LoadTestRunner(final TestUserConfiguration config, final AgentInfo agentInfo, final AbstractExecutionTimer timer)
+    public LoadTestRunner(final TestUserConfiguration config, final AgentInfo agentInfo, final AbstractExecutionTimer timer,
+                          final XltThreadFactory xltThreadFactory)
     {
-        // create a new thread group for each LoadTestRunner as a means
-        // to keep the main thread and any supporting threads together
-        super(new ThreadGroup(config.getUserId()), config.getUserId());
-
         this.config = config;
         this.agentInfo = agentInfo;
         this.timer = timer;
 
         status = new TestUserStatus();
         status.setUserName(config.getUserId());
+
+        thread = xltThreadFactory.newThread(this::run);
+        thread.setName(config.getUserId());
+    }
+
+    /**
+     * Returns the thread this runner is using under the hood.
+     * <p>
+     * Note: For unit-testing only.
+     * 
+     * @return the thread
+     */
+    Thread getThread()
+    {
+        return thread;
+    }
+
+    /**
+     * Starts this runner.
+     */
+    public void start()
+    {
+        thread.start();
+    }
+
+    /**
+     * Waits until this runner is finished.
+     */
+    public void join() throws InterruptedException
+    {
+        thread.join();
     }
 
     /**
@@ -110,8 +146,7 @@ public TestUserStatus getTestUserStatus()
     /**
      * Runs the test case as configured in the test case configuration.
      */
-    @Override
-    public void run()
+    private void run()
     {
         try
         {
@@ -196,7 +231,7 @@ public void run()
         }
         catch (final Exception ex)
         {
-            log.error("Failed to run test as user: " + getName(), ex);
+            log.error("Failed to run test as user: " + thread.getName(), ex);
 
             status.setState(TestUserStatus.State.Failed);
             status.setException(ex);

src/main/java/com/xceptance/xlt/common/XltConstants.java

@@ -509,4 +509,10 @@ private XltConstants()
      * The name of the HTML output file for rendering the scorecard report page.
      */
     public static final String SCORECARD_REPORT_HTML_FILENAME = "scorecard.html";
+
+    /*
+     * Virtual threads
+     */
+
+    public static final String PROP_VIRTUAL_THREADS_ENABLED = XLT_PACKAGE_PATH + ".virtualThreads.enabled";
 }

src/main/java/com/xceptance/xlt/engine/RequestQueue.java

@@ -22,7 +22,6 @@
 import java.util.concurrent.ThreadFactory;
 
 import com.xceptance.common.util.SynchronizingCounter;
-import com.xceptance.common.util.concurrent.DaemonThreadFactory;
 import com.xceptance.xlt.api.engine.Session;
 import com.xceptance.xlt.api.util.XltLogger;
 
@@ -74,14 +73,16 @@ public class RequestQueue
      *            the web client to use
      * @param threadCount
      *            the number of threads
+     * @param useVirtualThreads
+     *            whether to use virtual threads instead of platform threads
      */
-    public RequestQueue(final XltWebClient webClient, final int threadCount)
+    public RequestQueue(final XltWebClient webClient, final int threadCount, final boolean useVirtualThreads)
     {
         this.webClient = webClient;
         this.threadCount = threadCount;
         parallelModeEnabled = true;
 
-        final ThreadFactory threadFactory = new DaemonThreadFactory(i -> Session.getCurrent().getUserID() + "-pool-" + i);
+        final ThreadFactory threadFactory = new XltThreadFactory(useVirtualThreads, true, Session.getCurrent().getUserID() + "-pool-");
 
         executorService = Executors.newFixedThreadPool(threadCount, threadFactory);
         ongoingRequestsCount = new SynchronizingCounter(0);