Jetty 9.4.x 5859 classloader leak queuedthreadpool

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

@@ -689,6 +689,7 @@ public Thread newThread(Runnable runnable)
         thread.setDaemon(isDaemon());
         thread.setPriority(getThreadsPriority());
         thread.setName(_name + "-" + thread.getId());
+        thread.setContextClassLoader(this.getClass().getClassLoader());
         return thread;
     }
 

jetty-util/src/test/java/org/eclipse/jetty/util/thread/QueuedThreadPoolTest.java

@@ -19,6 +19,8 @@
 package org.eclipse.jetty.util.thread;
 
 import java.io.Closeable;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -27,6 +29,7 @@
 import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.log.StacklessLogging;
 import org.eclipse.jetty.util.thread.ThreadPool.SizedThreadPool;
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -833,6 +836,34 @@ public void testDump() throws Exception
         assertThat(count(dump, "QueuedThreadPoolTest.lambda$testDump$"), is(1));
     }
 
+    @Test
+    public void testContextClassLoader() throws Exception
+    {
+        QueuedThreadPool tp = new QueuedThreadPool();
+        tp.setMinThreads(1);
+        tp.setMaxThreads(3);
+        tp.setIdleTimeout(1000);
+        tp.setThreadsPriority(Thread.NORM_PRIORITY - 1);
+        try (StacklessLogging stackless = new StacklessLogging(QueuedThreadPool.class))
+        {
+            //change the current thread's classloader to something else
+            Thread.currentThread().setContextClassLoader(new URLClassLoader(new URL[] {}));
+
+            //create a new thread
+            Thread t = tp.newThread(() ->
+            {
+                //the executing thread should be still set to the classloader of the QueuedThreadPool,
+                //not that of the thread that created this thread.
+                assertThat(Thread.currentThread().getContextClassLoader(), Matchers.equalTo(QueuedThreadPool.class.getClassLoader()));
+            });
+
+            //new thread should be set to the classloader of the QueuedThreadPool
+            assertThat(t.getContextClassLoader(), Matchers.equalTo(QueuedThreadPool.class.getClassLoader()));
+
+            t.start();
+        }
+    }
+
     private int count(String s, String p)
     {
         int c = 0;