Fixes #1378 - Slow TLS clients may hang the server.

Properly overridden DecryptedEndPoint._writeCallback.isNonBlocking().

jetty-io/src/main/java/org/eclipse/jetty/io/ssl/SslConnection.java

@@ -345,6 +345,12 @@ public class SslConnection extends AbstractConnection
                     }
                 }, x);
             }
+
+            @Override
+            public boolean isNonBlocking()
+            {
+                return getWriteFlusher().isCallbackNonBlocking();
+            }
         };
 
         public DecryptedEndPoint()

jetty-server/src/test/java/org/eclipse/jetty/server/ssl/SlowClientsTest.java

@@ -0,0 +1,136 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+package org.eclipse.jetty.server.ssl;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InterruptedIOException;
+import java.io.OutputStream;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSocket;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.eclipse.jetty.server.Request;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.server.handler.AbstractHandler;
+import org.eclipse.jetty.toolchain.test.MavenTestingUtils;
+import org.eclipse.jetty.util.log.Log;
+import org.eclipse.jetty.util.log.Logger;
+import org.eclipse.jetty.util.ssl.SslContextFactory;
+import org.eclipse.jetty.util.thread.QueuedThreadPool;
+import org.junit.Test;
+
+public class SlowClientsTest
+{
+    private Logger logger = Log.getLogger(getClass());
+
+    @Test
+    public void testSlowClientsWithSmallThreadPool() throws Exception
+    {
+        File keystore = MavenTestingUtils.getTestResourceFile("keystore");
+        SslContextFactory sslContextFactory = new SslContextFactory();
+        sslContextFactory.setKeyStorePath(keystore.getAbsolutePath());
+        sslContextFactory.setKeyStorePassword("storepwd");
+        sslContextFactory.setKeyManagerPassword("keypwd");
+
+        int maxThreads = 8;
+        int contentLength = 32 * 1024 * 1024;
+        QueuedThreadPool serverThreads = new QueuedThreadPool(maxThreads);
+        serverThreads.setDetailedDump(true);
+        Server server = new Server(serverThreads);
+        try
+        {
+            ServerConnector connector = new ServerConnector(server, 1, 1, sslContextFactory);
+            connector.setPort(8888);
+            server.addConnector(connector);
+            server.setHandler(new AbstractHandler()
+            {
+                @Override
+                public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
+                {
+                    baseRequest.setHandled(true);
+                    logger.info("SERVING {}", target);
+                    // Write some big content.
+                    response.getOutputStream().write(new byte[contentLength]);
+                    logger.info("SERVED {}", target);
+                }
+            });
+            server.start();
+
+            SSLContext sslContext = sslContextFactory.getSslContext();
+
+            CompletableFuture[] futures = new CompletableFuture[2 * maxThreads];
+            ExecutorService executor = Executors.newFixedThreadPool(futures.length);
+            for (int i = 0; i < futures.length; i++)
+            {
+                int k = i;
+                futures[i] = CompletableFuture.runAsync(() ->
+                {
+                    try (SSLSocket socket = (SSLSocket)sslContext.getSocketFactory().createSocket("localhost", connector.getLocalPort()))
+                    {
+                        socket.setSoTimeout(contentLength / 1024);
+                        OutputStream output = socket.getOutputStream();
+                        String target = "/" + k;
+                        String request = "GET " + target + " HTTP/1.1\r\n" +
+                                "Host: localhost\r\n" +
+                                "Connection: close\r\n" +
+                                "\r\n";
+                        output.write(request.getBytes(StandardCharsets.UTF_8));
+                        output.flush();
+
+                        while (serverThreads.getIdleThreads() > 0)
+                            Thread.sleep(50);
+
+                        InputStream input = socket.getInputStream();
+                        while (true)
+                        {
+                            int read = input.read();
+                            if (read < 0)
+                                break;
+                        }
+                        logger.info("FINISHED {}", target);
+                    }
+                    catch (IOException x)
+                    {
+                        throw new UncheckedIOException(x);
+                    }
+                    catch (InterruptedException x)
+                    {
+                        throw new UncheckedIOException(new InterruptedIOException());
+                    }
+                }, executor);
+            }
+            CompletableFuture.allOf(futures).join();
+        }
+        finally
+        {
+            server.stop();
+        }
+    }
+}