Merge remote-tracking branch 'origin/jetty-10.0.x' into jetty-11.0.x

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

@@ -0,0 +1,51 @@
+//
+// ========================================================================
+// Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+// ========================================================================
+//
+
+package org.eclipse.jetty.util.thread;
+
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.function.Supplier;
+
+/**
+ * Convenience class to ensure that a new Thread is created
+ * inside a privileged block. 
+ * 
+ * This prevents the Thread constructor
+ * from pinning the caller's context classloader. This happens
+ * when the Thread constructor takes a snapshot of the current
+ * calling context - which contains ProtectionDomains that may
+ * reference the context classloader - and remembers it for the
+ * lifetime of the Thread.
+ */
+class PrivilegedThreadFactory
+{
+    /**
+     * Use a Supplier to make a new thread, calling it within
+     * a privileged block to prevent classloader pinning.
+     * 
+     * @param newThreadSupplier a Supplier to create a fresh thread
+     * @return a new thread, protected from classloader pinning.
+     */
+    static <T extends Thread> T newThread(Supplier<T> newThreadSupplier)
+    {
+        return AccessController.doPrivileged(new PrivilegedAction<T>()
+        {
+            @Override
+            public T run()
+            {
+                return newThreadSupplier.get();
+            }
+        });
+    }
+}

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

@@ -15,6 +15,8 @@ package org.eclipse.jetty.util.thread;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
@@ -697,11 +699,15 @@ public class QueuedThreadPool extends ContainerLifeCycle implements ThreadFactor
     @Override
     public Thread newThread(Runnable runnable)
     {
-        Thread thread = new Thread(_threadGroup, runnable);
-        thread.setDaemon(isDaemon());
-        thread.setPriority(getThreadsPriority());
-        thread.setName(_name + "-" + thread.getId());
-        return thread;
+        return PrivilegedThreadFactory.newThread(() ->
+        {
+            Thread thread = new Thread(_threadGroup, runnable);
+            thread.setDaemon(isDaemon());
+            thread.setPriority(getThreadsPriority());
+            thread.setName(_name + "-" + thread.getId());
+            thread.setContextClassLoader(getClass().getClassLoader());
+            return thread;
+        });
     }
 
     protected void removeThread(Thread thread)

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

@@ -13,6 +13,8 @@
 
 package org.eclipse.jetty.util.thread;
 
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -31,7 +33,10 @@ import org.slf4j.LoggerFactory;
 public class ShutdownThread extends Thread
 {
     private static final Logger LOG = LoggerFactory.getLogger(ShutdownThread.class);
-    private static final ShutdownThread _thread = new ShutdownThread();
+    private static final ShutdownThread _thread = PrivilegedThreadFactory.newThread(() ->
+    {
+        return new ShutdownThread();
+    });
 
     private final AutoLock _lock = new AutoLock();
     private boolean _hooked;

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

@@ -14,6 +14,8 @@
 package org.eclipse.jetty.util.thread;
 
 import java.io.Closeable;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.time.Duration;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -22,6 +24,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 import org.eclipse.jetty.logging.StacklessLogging;
 import org.eclipse.jetty.util.component.LifeCycle;
 import org.eclipse.jetty.util.thread.ThreadPool.SizedThreadPool;
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -849,6 +852,28 @@ public class QueuedThreadPoolTest extends AbstractThreadPoolTest
         assertThat(count(dump, "QueuedThreadPoolTest.lambda$testDump$"), is(1));
     }
 
+    @Test
+    public void testContextClassLoader() throws Exception
+    {
+        QueuedThreadPool tp = new QueuedThreadPool();
+        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()));
+        }
+    }
+    
     private int count(String s, String p)
     {
         int c = 0;