Issue #354 (Spin loop in case of exception thrown during accept()).

Fixed by introducing an overridable method that performs an arbitrary
sleep to avoid the spin loop. Subclasses may customize.

jetty-server/src/main/java/org/eclipse/jetty/server/AbstractConnector.java

@@ -528,6 +528,34 @@ public abstract class AbstractConnector extends ContainerLifeCycle implements Co
         return getConnectionFactory(_defaultProtocol);
     }
 
+    protected boolean handleAcceptFailure(Throwable previous, Throwable current)
+    {
+        if (isAccepting())
+        {
+            if (previous == null)
+                LOG.warn(current);
+            else
+                LOG.debug(current);
+        }
+        else
+        {
+            LOG.ignore(current);
+        }
+
+        try
+        {
+            // Arbitrary sleep to avoid spin looping.
+            // Subclasses may decide for a different
+            // sleep policy or closing the connector.
+            Thread.sleep(1000);
+            return true;
+        }
+        catch (Throwable x)
+        {
+            return false;
+        }
+    }
+
     private class Acceptor implements Runnable
     {
         private final int _id;
@@ -557,18 +585,20 @@ public abstract class AbstractConnector extends ContainerLifeCycle implements Co
 
             try
             {
+                Throwable exception = null;
                 while (isAccepting())
                 {
                     try
                     {
                         accept(_id);
+                        exception = null;
                     }
-                    catch (Throwable e)
+                    catch (Throwable x)
                     {
-                        if (isAccepting())
-                            LOG.warn(e);
+                        if (handleAcceptFailure(exception, x))
+                            exception = x;
                         else
-                            LOG.ignore(e);
+                            break;
                     }
                 }
             }

jetty-server/src/test/java/org/eclipse/jetty/server/ServerConnectorTest.java

@@ -28,6 +28,7 @@ import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.charset.StandardCharsets;
 import java.util.Collection;
+import java.util.concurrent.atomic.AtomicLong;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
@@ -40,6 +41,7 @@ import org.eclipse.jetty.server.handler.DefaultHandler;
 import org.eclipse.jetty.server.handler.HandlerList;
 import org.eclipse.jetty.toolchain.test.OS;
 import org.eclipse.jetty.util.IO;
+import org.hamcrest.Matchers;
 import org.junit.Test;
 
 import static org.hamcrest.Matchers.anyOf;
@@ -235,4 +237,32 @@ public class ServerConnectorTest
         assertEquals(2, connector.getBeans(ConnectionFactory.class).size());
         assertEquals(proxy.getProtocol(), connector.getDefaultProtocol());
     }
+
+    @Test
+    public void testExceptionWhileAccepting() throws Exception
+    {
+        Server server = new Server();
+        AtomicLong spins = new AtomicLong();
+        ServerConnector connector = new ServerConnector(server)
+        {
+            @Override
+            public void accept(int acceptorID) throws IOException
+            {
+                spins.incrementAndGet();
+                throw new IOException("explicitly_thrown_by_test");
+            }
+        };
+        server.addConnector(connector);
+        server.start();
+
+        try
+        {
+            Thread.sleep(1000);
+            assertThat(spins.get(), Matchers.lessThan(5L));
+        }
+        finally
+        {
+            server.stop();
+        }
+    }
 }