Jetty 9.4.x 1803 proposal 0 - single ReservedThreadExecutor (#2119)

Issue #1803 - Review usage of scheduling strategies

Use a single ReservedThreadExecutor built into the QueuedThreadPool
via new interface TryExecutor.

Signed-off-by: Greg Wilkins <gregw@webtide.com>
Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-http2/http2-client/src/main/java/org/eclipse/jetty/http2/client/HTTP2ClientConnectionFactory.java

@@ -39,7 +39,6 @@ import org.eclipse.jetty.io.EndPoint;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.Promise;
 import org.eclipse.jetty.util.component.LifeCycle;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
 import org.eclipse.jetty.util.thread.Scheduler;
 
 public class HTTP2ClientConnectionFactory implements ClientConnectionFactory
@@ -69,36 +68,19 @@ public class HTTP2ClientConnectionFactory implements ClientConnectionFactory
         HTTP2ClientSession session = new HTTP2ClientSession(scheduler, endPoint, generator, listener, flowControl);
         Parser parser = new Parser(byteBufferPool, session, 4096, 8192);
 
-        ReservedThreadExecutor reservedExecutor = provideReservedThreadExecutor(client, executor);
+        HTTP2ClientConnection connection = new HTTP2ClientConnection(client, byteBufferPool, executor, endPoint,
-
-        HTTP2ClientConnection connection = new HTTP2ClientConnection(client, byteBufferPool, reservedExecutor, endPoint,
                 parser, session, client.getInputBufferSize(), promise, listener);
         connection.addListener(connectionListener);
         return customize(connection, context);
     }
 
-    protected ReservedThreadExecutor provideReservedThreadExecutor(HTTP2Client client, Executor executor)
-    {
-        synchronized (this)
-        {
-            ReservedThreadExecutor reservedExecutor = client.getBean(ReservedThreadExecutor.class);
-            if (reservedExecutor == null)
-            {
-                // TODO: see HTTP2Connection.FillableCallback
-                reservedExecutor = new ReservedThreadExecutor(executor, 0);
-                client.addManaged(reservedExecutor);
-            }
-            return reservedExecutor;
-        }
-    }
-
     private class HTTP2ClientConnection extends HTTP2Connection implements Callback
     {
         private final HTTP2Client client;
         private final Promise<Session> promise;
         private final Session.Listener listener;
 
-        private HTTP2ClientConnection(HTTP2Client client, ByteBufferPool byteBufferPool, ReservedThreadExecutor executor, EndPoint endpoint, Parser parser, ISession session, int bufferSize, Promise<Session> promise, Session.Listener listener)
+        private HTTP2ClientConnection(HTTP2Client client, ByteBufferPool byteBufferPool, Executor executor, EndPoint endpoint, Parser parser, ISession session, int bufferSize, Promise<Session> promise, Session.Listener listener)
         {
             super(byteBufferPool, executor, endpoint, parser, session, bufferSize);
             this.client = client;

jetty-http2/http2-common/src/main/java/org/eclipse/jetty/http2/HTTP2Connection.java

@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.ArrayDeque;
 import java.util.Queue;
+import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicLong;
 
 import org.eclipse.jetty.http2.parser.Parser;
@@ -35,7 +36,7 @@ import org.eclipse.jetty.util.component.LifeCycle;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.thread.ExecutionStrategy;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
+import org.eclipse.jetty.util.thread.TryExecutor;
 import org.eclipse.jetty.util.thread.strategy.EatWhatYouKill;
 
 public class HTTP2Connection extends AbstractConnection implements WriteFlusher.Listener
@@ -51,14 +52,15 @@ public class HTTP2Connection extends AbstractConnection implements WriteFlusher.
     private final int bufferSize;
     private final ExecutionStrategy strategy;
 
-    public HTTP2Connection(ByteBufferPool byteBufferPool, ReservedThreadExecutor executor, EndPoint endPoint, Parser parser, ISession session, int bufferSize)
+    public HTTP2Connection(ByteBufferPool byteBufferPool, Executor executor, EndPoint endPoint, Parser parser, ISession session, int bufferSize)
     {
-        super(endPoint, executor.getExecutor());
+        super(endPoint, executor);
         this.byteBufferPool = byteBufferPool;
         this.parser = parser;
         this.session = session;
         this.bufferSize = bufferSize;
-        this.strategy = new EatWhatYouKill(producer, executor.getExecutor(), executor);
+        // TODO HTTP2 cannot use EWYK without fix for #1803
+        this.strategy = new EatWhatYouKill(producer, new TryExecutor.NoTryExecutor(executor));
         LifeCycle.start(strategy);
     }
 

jetty-http2/http2-server/src/main/config/etc/jetty-http2.xml

@@ -12,7 +12,6 @@
         <Set name="maxConcurrentStreams"><Property name="jetty.http2.maxConcurrentStreams" deprecated="http2.maxConcurrentStreams" default="128"/></Set>
         <Set name="initialStreamRecvWindow"><Property name="jetty.http2.initialStreamRecvWindow" default="524288"/></Set>
         <Set name="initialSessionRecvWindow"><Property name="jetty.http2.initialSessionRecvWindow" default="1048576"/></Set>
-        <Set name="reservedThreads"><Property name="jetty.http2.reservedThreads" default="-1"/></Set>
       </New>
     </Arg>
   </Call>

jetty-http2/http2-server/src/main/config/modules/http2.mod

@@ -27,7 +27,3 @@ etc/jetty-http2.xml
 
 ## Initial session receive window (client to server)
 # jetty.http2.initialSessionRecvWindow=1048576
-
-## Reserve threads for high priority tasks (-1 use number of Selectors, 0 no reserved threads)
-# jetty.http2.reservedThreads=-1
-

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/AbstractHTTP2ServerConnectionFactory.java

@@ -35,7 +35,6 @@ import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 import org.eclipse.jetty.util.annotation.Name;
 import org.eclipse.jetty.util.component.LifeCycle;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
 
 @ManagedObject
 public abstract class AbstractHTTP2ServerConnectionFactory extends AbstractConnectionFactory
@@ -49,7 +48,6 @@ public abstract class AbstractHTTP2ServerConnectionFactory extends AbstractConne
     private int maxHeaderBlockFragment = 0;
     private FlowControlStrategy.Factory flowControlStrategyFactory = () -> new BufferingFlowControlStrategy(0.5F);
     private long streamIdleTimeout;
-    private int reservedThreads;
 
     public AbstractHTTP2ServerConnectionFactory(@Name("config") HttpConfiguration httpConfiguration)
     {
@@ -143,20 +141,23 @@ public abstract class AbstractHTTP2ServerConnectionFactory extends AbstractConne
     }
 
     /**
-     * @see ReservedThreadExecutor
+     * @return -1
-     * @return The number of reserved threads
+     * @deprecated
      */
-    @ManagedAttribute("The number of threads reserved for high priority tasks")
+    @Deprecated
     public int getReservedThreads()
     {
-        return reservedThreads;
+        return -1;
     }
 
+    /**
+     * @param threads ignored
+     * @deprecated
+     */
+    @Deprecated
     public void setReservedThreads(int threads)
     {
-        // TODO: see also HTTP2Connection.FillableCallback.
+        throw new UnsupportedOperationException();
-        // TODO: currently disabled since the only value that works is 0.
-//        this.reservedThreads = threads;
     }
 
     public HttpConfiguration getHttpConfiguration()
@@ -183,30 +184,14 @@ public abstract class AbstractHTTP2ServerConnectionFactory extends AbstractConne
             streamIdleTimeout = endPoint.getIdleTimeout();
         session.setStreamIdleTimeout(streamIdleTimeout);
         session.setInitialSessionRecvWindow(getInitialSessionRecvWindow());
-
-        ReservedThreadExecutor executor = provideReservedThreadExecutor(connector);
         
         ServerParser parser = newServerParser(connector, session);
-        HTTP2Connection connection = new HTTP2ServerConnection(connector.getByteBufferPool(), executor,
+        HTTP2Connection connection = new HTTP2ServerConnection(connector.getByteBufferPool(), connector.getExecutor(),
                         endPoint, httpConfiguration, parser, session, getInputBufferSize(), listener);
         connection.addListener(connectionListener);
         return configure(connection, connector, endPoint);
     }
 
-    protected ReservedThreadExecutor provideReservedThreadExecutor(Connector connector)
-    {
-        synchronized (this)
-        {
-            ReservedThreadExecutor executor = getBean(ReservedThreadExecutor.class);
-            if (executor == null)
-            {
-                executor = new ReservedThreadExecutor(connector.getExecutor(), getReservedThreads());
-                addManaged(executor);
-            }
-            return executor;
-        }
-    }
-
     protected abstract ServerSessionListener newSessionListener(Connector connector, EndPoint endPoint);
 
     protected ServerParser newServerParser(Connector connector, ServerParser.Listener listener)

jetty-http2/http2-server/src/main/java/org/eclipse/jetty/http2/server/HTTP2ServerConnection.java

@@ -26,6 +26,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Queue;
+import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicLong;
 
 import org.eclipse.jetty.http.BadMessageException;
@@ -58,7 +59,6 @@ import org.eclipse.jetty.util.BufferUtil;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.CountingCallback;
 import org.eclipse.jetty.util.TypeUtil;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
 
 public class HTTP2ServerConnection extends HTTP2Connection implements Connection.UpgradeTo
 {
@@ -94,7 +94,7 @@ public class HTTP2ServerConnection extends HTTP2Connection implements Connection
     private final HttpConfiguration httpConfig;
     private boolean recycleHttpChannels;
 
-    public HTTP2ServerConnection(ByteBufferPool byteBufferPool, ReservedThreadExecutor executor, EndPoint endPoint, HttpConfiguration httpConfig, ServerParser parser, ISession session, int inputBufferSize, ServerSessionListener listener)
+    public HTTP2ServerConnection(ByteBufferPool byteBufferPool, Executor executor, EndPoint endPoint, HttpConfiguration httpConfig, ServerParser parser, ISession session, int inputBufferSize, ServerSessionListener listener)
     {
         super(byteBufferPool, executor, endPoint, parser, session, inputBufferSize);
         this.listener = listener;

jetty-io/src/main/java/org/eclipse/jetty/io/ManagedSelector.java

@@ -48,7 +48,6 @@ import org.eclipse.jetty.util.component.DumpableCollection;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.thread.ExecutionStrategy;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
 import org.eclipse.jetty.util.thread.Scheduler;
 import org.eclipse.jetty.util.thread.strategy.EatWhatYouKill;
 
@@ -77,7 +76,7 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
         _id = id;
         SelectorProducer producer = new SelectorProducer();
         Executor executor = selectorManager.getExecutor();
-        _strategy = new EatWhatYouKill(producer,executor,_selectorManager.getBean(ReservedThreadExecutor.class));
+        _strategy = new EatWhatYouKill(producer,executor);
         addBean(_strategy,true);
         setStopTimeout(5000);
     }
@@ -136,17 +135,17 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
 
     /**
      * Submit an {@link SelectorUpdate} to be acted on between calls to {@link Selector#select()}
-     * @param action
+     * @param update The selector update to apply at next wakeup
      */
-    public void submit(SelectorUpdate action)
+    public void submit(SelectorUpdate update)
     {
         if (LOG.isDebugEnabled())
-            LOG.debug("Queued change {} on {}", action, this);
+            LOG.debug("Queued change {} on {}", update, this);
 
         Selector selector = null;
         synchronized(ManagedSelector.this)
         {
-            _updates.offer(action);
+            _updates.offer(update);
             
             if (_selecting)
             {
@@ -265,15 +264,15 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
     {
         Selector selector = _selector;
         List<String> keys = null;
-        List<SelectorUpdate> actions = null;
+        List<SelectorUpdate> updates = null;
         if (selector != null && selector.isOpen())
         {
             DumpKeys dump = new DumpKeys();
-            String actionsAt;
+            String updatesAt;
             synchronized(ManagedSelector.this)
             {
-                actionsAt = DateTimeFormatter.ISO_OFFSET_DATE_TIME.format(ZonedDateTime.now());
+                updatesAt = DateTimeFormatter.ISO_OFFSET_DATE_TIME.format(ZonedDateTime.now());
-                actions = new ArrayList<>(_updates);
+                updates = new ArrayList<>(_updates);
                 _updates.addFirst(dump);
                 _selecting = false;
             }
@@ -282,7 +281,7 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
             String keysAt = DateTimeFormatter.ISO_OFFSET_DATE_TIME.format(ZonedDateTime.now());
             if (keys==null)
                 keys = Collections.singletonList("No dump keys retrieved");
-            dumpBeans(out, indent, Arrays.asList(new DumpableCollection("actions @ "+actionsAt, actions),
+            dumpBeans(out, indent, Arrays.asList(new DumpableCollection("updates @ "+updatesAt, updates),
                     new DumpableCollection("keys @ "+keysAt, keys)));
         }
         else
@@ -295,7 +294,7 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
     public String toString()
     {
         Selector selector = _selector;
-        return String.format("%s id=%s keys=%d selected=%d actions=%d",
+        return String.format("%s id=%s keys=%d selected=%d updates=%d",
                 super.toString(),
                 _id,
                 selector != null && selector.isOpen() ? selector.keys().size() : -1,
@@ -377,16 +376,16 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
             _updateable.clear();
 
             Selector selector;
-            int actions;
+            int updates;
             synchronized(ManagedSelector.this)
             {
-                actions = _updates.size();
+                updates = _updates.size();
-                _selecting = actions==0;
+                _selecting = updates==0;
                 selector = _selecting?null:_selector;
             }
 
             if (LOG.isDebugEnabled())
-                LOG.debug("actions {}",actions);
+                LOG.debug("updates {}",updates);
             
             if (selector != null)
                 selector.wakeup();           
@@ -405,18 +404,18 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
                     if (LOG.isDebugEnabled())
                         LOG.debug("Selector {} woken up from select, {}/{} selected", selector, selected, selector.keys().size());
 
-                    int actions;
+                    int updates;
                     synchronized(ManagedSelector.this)
                     {
                         // finished selecting
                         _selecting = false;
-                        actions = _updates.size();
+                        updates = _updates.size();
                     }
 
                     _keys = selector.selectedKeys();
                     _cursor = _keys.iterator();
                     if (LOG.isDebugEnabled())
-                        LOG.debug("Selector {} processing {} keys, {} actions", selector, _keys.size(), actions);
+                        LOG.debug("Selector {} processing {} keys, {} updates", selector, _keys.size(), updates);
 
                     return true;
                 }
@@ -489,7 +488,7 @@ public class ManagedSelector extends ContainerLifeCycle implements Dumpable
         {
             // Do update keys for only previously selected keys.
             // This will update only those keys whose selection did not cause an
-            // updateKeys action to be submitted.
+            // updateKeys update to be submitted.
             for (SelectionKey key : _keys)
                 updateKey(key);
             _keys.clear();

jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java

@@ -38,11 +38,9 @@ import org.eclipse.jetty.util.component.ContainerLifeCycle;
 import org.eclipse.jetty.util.component.Dumpable;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
 import org.eclipse.jetty.util.thread.Scheduler;
 import org.eclipse.jetty.util.thread.ThreadPool;
 import org.eclipse.jetty.util.thread.ThreadPoolBudget;
-import org.eclipse.jetty.util.thread.strategy.EatWhatYouKill;
 
 /**
  * <p>{@link SelectorManager} manages a number of {@link ManagedSelector}s that
@@ -63,9 +61,7 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
     private final AtomicInteger _selectorIndex = new AtomicInteger();
     private final IntUnaryOperator _selectorIndexUpdate;
     private long _connectTimeout = DEFAULT_CONNECT_TIMEOUT;
-    private int _reservedThreads = -1;
     private ThreadPoolBudget.Lease _lease;
-    private ReservedThreadExecutor _reservedThreadExecutor;
 
     private static int defaultSelectors(Executor executor)
     {
@@ -133,34 +129,23 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
     }
 
     /**
-     * Get the number of preallocated producing threads
+     * @return -1
-     * @see EatWhatYouKill
+     * @deprecated
-     * @see ReservedThreadExecutor
-     * @return The number of threads preallocated to producing (default -1).
      */
-    @ManagedAttribute("The number of reserved producer threads")
+    @Deprecated
     public int getReservedThreads()
     {
-        return _reservedThreads;
+        return -1;
     }
-    
+
     /**
-     * Set the number of reserved threads for high priority tasks.
+     * @param threads ignored
-     * <p>Reserved threads are used to take over producing duties, so that a 
+     * @deprecated
-     * producer thread may immediately consume a task it has produced (EatWhatYouKill
-     * scheduling). If a reserved thread is not available, then produced tasks must
-     * be submitted to an executor to be executed by a different thread.
-     * @see EatWhatYouKill
-     * @see ReservedThreadExecutor
-     * @param threads  The number of producing threads to preallocate. If 
-     * less that 0 (the default), then a heuristic based on the number of CPUs and
-     * the thread pool size is used to select the number of threads. If 0, no 
-     * threads are preallocated and the EatWhatYouKill scheduler will be 
-     * disabled and all produced tasks will be executed in a separate thread. 
      */
+    @Deprecated
     public void setReservedThreads(int threads)
     {
-        _reservedThreads = threads;
+        throw new UnsupportedOperationException();
     }
     
     /**
@@ -182,7 +167,7 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
         return _selectors.length;
     }
 
-    private ManagedSelector chooseSelector(SelectableChannel channel)
+    private ManagedSelector chooseSelector()
     {
         return _selectors[_selectorIndex.updateAndGet(_selectorIndexUpdate)];
     }
@@ -199,7 +184,7 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
      */
     public void connect(SelectableChannel channel, Object attachment)
     {
-        ManagedSelector set = chooseSelector(channel);
+        ManagedSelector set = chooseSelector();
         set.submit(set.new Connect(channel, attachment));
     }
 
@@ -224,7 +209,7 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
      */
     public void accept(SelectableChannel channel, Object attachment)
     {
-        final ManagedSelector selector = chooseSelector(channel);
+        final ManagedSelector selector = chooseSelector();
         selector.submit(selector.new Accept(channel, attachment));
     }
 
@@ -239,7 +224,7 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
      */
     public Closeable acceptor(SelectableChannel server)
     {
-        final ManagedSelector selector = chooseSelector(null);
+        final ManagedSelector selector = chooseSelector();
         ManagedSelector.Acceptor acceptor = selector.new Acceptor(server);
         selector.submit(acceptor);
         return acceptor;
@@ -262,8 +247,6 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
     @Override
     protected void doStart() throws Exception
     {
-        _reservedThreadExecutor = new ReservedThreadExecutor(getExecutor(),_reservedThreads,this);
-        addBean(_reservedThreadExecutor,true);
         _lease = ThreadPoolBudget.leaseFrom(getExecutor(), this, _selectors.length);
         for (int i = 0; i < _selectors.length; i++)
         {
@@ -301,9 +284,6 @@ public abstract class SelectorManager extends ContainerLifeCycle implements Dump
                     removeBean(selector);
             }
             Arrays.fill(_selectors,null);
-            if (_reservedThreadExecutor!=null)
-                removeBean(_reservedThreadExecutor);
-            _reservedThreadExecutor = null;
             if (_lease != null)
                 _lease.close();
         }

jetty-osgi/test-jetty-osgi/src/test/config/etc/jetty-http2.xml

@@ -12,7 +12,6 @@
         <Set name="maxConcurrentStreams"><Property name="jetty.http2.maxConcurrentStreams" deprecated="http2.maxConcurrentStreams" default="128"/></Set>
         <Set name="initialStreamRecvWindow"><Property name="jetty.http2.initialStreamRecvWindow" default="524288"/></Set>
         <Set name="initialSessionRecvWindow"><Property name="jetty.http2.initialSessionRecvWindow" default="1048576"/></Set>
-        <Set name="reservedThreads"><Property name="jetty.http2.reservedThreads" default="-1"/></Set>
       </New>
     </Arg>
   </Call>

jetty-server/src/main/config/etc/jetty-http.xml

@@ -42,7 +42,6 @@
         <Set name="acceptQueueSize"><Property name="jetty.http.acceptQueueSize" deprecated="http.acceptQueueSize" default="0"/></Set>
         <Get name="SelectorManager">
           <Set name="connectTimeout"><Property name="jetty.http.connectTimeout" default="15000"/></Set>
-          <Set name="reservedThreads"><Property name="jetty.http.reservedThreads" default="-2"/></Set>
         </Get>
       </New>
     </Arg>

jetty-server/src/main/config/etc/jetty-ssl.xml

@@ -34,7 +34,6 @@
         <Set name="acceptQueueSize"><Property name="jetty.ssl.acceptQueueSize" deprecated="ssl.acceptQueueSize" default="0"/></Set>
         <Get name="SelectorManager">
           <Set name="connectTimeout"><Property name="jetty.ssl.connectTimeout" default="15000"/></Set>
-          <Set name="reservedThreads"><Property name="jetty.ssl.reservedThreads" default="-2"/></Set>
         </Get>
       </New>
     </Arg>

jetty-server/src/main/config/etc/jetty-threadpool.xml

@@ -22,6 +22,7 @@
   <!-- =========================================================== -->
   <Set name="minThreads" type="int"><Property name="jetty.threadPool.minThreads" deprecated="threads.min" default="10"/></Set>
   <Set name="maxThreads" type="int"><Property name="jetty.threadPool.maxThreads" deprecated="threads.max" default="200"/></Set>
+  <Set name="reservedThreads" type="int"><Property name="jetty.threadPool.reservedThreads" default="-1"/></Set>
   <Set name="idleTimeout" type="int"><Property name="jetty.threadPool.idleTimeout" deprecated="threads.timeout" default="60000"/></Set>
   <Set name="detailedDump" type="boolean"><Property name="jetty.threadPool.detailedDump" default="false"/></Set>
 </Configure>

jetty-server/src/main/config/etc/jetty.xml

@@ -24,7 +24,6 @@
 <!-- configuration that may be set here.                             -->
 <!-- =============================================================== -->
 <Configure id="Server" class="org.eclipse.jetty.server.Server">
-
     <Arg name="threadpool"><Ref refid="threadPool"/></Arg>
 
     <!-- =========================================================== -->

jetty-server/src/main/config/modules/http.mod

@@ -40,9 +40,6 @@ etc/jetty-http.xml
 ## Thread priority delta to give to acceptor threads
 # jetty.http.acceptorPriorityDelta=0
 
-## Reserve threads for high priority tasks (-1 use a heuristic, 0 no reserved threads)
-# jetty.http.reservedThreads=-1
-
 ## Connect Timeout in milliseconds
 # jetty.http.connectTimeout=15000
 

jetty-server/src/main/config/modules/ssl.mod

@@ -44,9 +44,6 @@ basehome:modules/ssl/keystore|etc/keystore
 ## Thread priority delta to give to acceptor threads
 # jetty.ssl.acceptorPriorityDelta=0
 
-## Preallocated producer threads (0 disables EatWhatYouKill scheduling)
-# jetty.ssl.reservedThreads=-1
-
 ## Connect Timeout in milliseconds
 # jetty.ssl.connectTimeout=15000
 

jetty-server/src/main/config/modules/threadpool.mod

@@ -13,6 +13,9 @@ etc/jetty-threadpool.xml
 ## Maximum Number of Threads
 #jetty.threadPool.maxThreads=200
 
+## Number of reserved threads (-1 for heuristic)
+# jetty.threadPool.reservedThreads=-1
+
 ## Thread Idle Timeout (in milliseconds)
 #jetty.threadPool.idleTimeout=60000
 

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

@@ -36,7 +36,6 @@ import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 import org.eclipse.jetty.util.annotation.ManagedOperation;
 import org.eclipse.jetty.util.annotation.Name;
-import org.eclipse.jetty.util.component.AbstractLifeCycle;
 import org.eclipse.jetty.util.component.ContainerLifeCycle;
 import org.eclipse.jetty.util.component.Dumpable;
 import org.eclipse.jetty.util.component.DumpableCollection;
@@ -46,7 +45,7 @@ import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.thread.ThreadPool.SizedThreadPool;
 
 @ManagedObject("A thread pool")
-public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPool, Dumpable
+public class QueuedThreadPool extends ContainerLifeCycle implements SizedThreadPool, Dumpable, TryExecutor
 {
     private static final Logger LOG = Log.getLogger(QueuedThreadPool.class);
 
@@ -61,6 +60,8 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
     private int _idleTimeout;
     private int _maxThreads;
     private int _minThreads;
+    private int _reservedThreads = -1;
+    private TryExecutor _tryExecutor = TryExecutor.NO_TRY;
     private int _priority = Thread.NORM_PRIORITY;
     private boolean _daemon = false;
     private boolean _detailedDump = false;
@@ -93,12 +94,17 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
     }
 
     public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("queue") BlockingQueue<Runnable> queue, @Name("threadGroup") ThreadGroup threadGroup)
+    {
+        this(maxThreads, minThreads, idleTimeout, -1, queue, threadGroup);
+    }
+    
+    public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("reservedThreads") int reservedThreads, @Name("queue") BlockingQueue<Runnable> queue, @Name("threadGroup") ThreadGroup threadGroup)
     {
         setMinThreads(minThreads);
         setMaxThreads(maxThreads);
         setIdleTimeout(idleTimeout);
         setStopTimeout(5000);
-
+        setReservedThreads(reservedThreads);
         if (queue==null)
         {
             int capacity=Math.max(_minThreads, 8);
@@ -106,7 +112,7 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         }
         _jobs=queue;
         _threadGroup=threadGroup;
-        _budget=new ThreadPoolBudget(this);
+        setThreadPoolBudget(new ThreadPoolBudget(this));
     }
 
     @Override
@@ -125,15 +131,21 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
     @Override
     protected void doStart() throws Exception
     {
+        _tryExecutor = new ReservedThreadExecutor(this,_reservedThreads);
+        addBean(_tryExecutor);
+        
         super.doStart();
         _threadsStarted.set(0);
 
-        startThreads(_minThreads);
+        startThreads(_minThreads);  
     }
 
     @Override
     protected void doStop() throws Exception
     {
+        removeBean(_tryExecutor);
+        _tryExecutor = TryExecutor.NO_TRY;
+        
         super.doStop();
 
         long timeout = getStopTimeout();
@@ -222,7 +234,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
      * Set the maximum thread idle time.
      * Threads that are idle for longer than this period may be
      * stopped.
-     * Delegated to the named or anonymous Pool.
      *
      * @param idleTimeout Max idle time in ms.
      * @see #getIdleTimeout
@@ -234,7 +245,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
 
     /**
      * Set the maximum number of threads.
-     * Delegated to the named or anonymous Pool.
      *
      * @param maxThreads maximum number of threads.
      * @see #getMaxThreads
@@ -249,7 +259,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
 
     /**
      * Set the minimum number of threads.
-     * Delegated to the named or anonymous Pool.
      *
      * @param minThreads minimum number of threads
      * @see #getMinThreads
@@ -266,6 +275,19 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         if (isStarted() && threads < _minThreads)
             startThreads(_minThreads - threads);
     }
+    
+    /**
+     * Set the number of reserved threads.
+     *
+     * @param reservedThreads number of reserved threads or -1 for heuristically determined 
+     * @see #getReservedThreads
+     */
+    public void setReservedThreads(int reservedThreads)
+    {
+        if (isRunning())
+            throw new IllegalStateException(getState());
+        _reservedThreads = reservedThreads;
+    }
 
     /**
      * @param name Name of this thread pool to use when naming threads.
@@ -289,7 +311,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
 
     /**
      * Get the maximum thread idle time.
-     * Delegated to the named or anonymous Pool.
      *
      * @return Max idle time in ms.
      * @see #setIdleTimeout
@@ -302,7 +323,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
 
     /**
      * Get the maximum number of threads.
-     * Delegated to the named or anonymous Pool.
      *
      * @return maximum number of threads.
      * @see #setMaxThreads
@@ -316,7 +336,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
 
     /**
      * Get the minimum number of threads.
-     * Delegated to the named or anonymous Pool.
      *
      * @return minimum number of threads.
      * @see #setMinThreads
@@ -328,6 +347,20 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         return _minThreads;
     }
 
+    /**
+     * Get the number of reserved threads.
+     *
+     * @return number of reserved threads or or -1 for heuristically determined
+     * @see #setReservedThreads
+     */
+    @ManagedAttribute("the number of reserved threads in the pool")
+    public int getReservedThreads()
+    {
+        if (isStarted())
+            return getBean(ReservedThreadExecutor.class).getCapacity();
+        return _reservedThreads;
+    }
+
     /**
      * @return The name of the this thread pool
      */
@@ -409,6 +442,13 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         }
     }
 
+    @Override
+    public boolean tryExecute(Runnable task)
+    {
+        TryExecutor tryExecutor = _tryExecutor;
+        return tryExecutor!=null && tryExecutor.tryExecute(task);
+    }
+
     /**
      * Blocks until the thread pool is {@link LifeCycle#stop stopped}.
      */
@@ -509,13 +549,6 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         return new Thread(_threadGroup, runnable);
     }
 
-    @Override
-    @ManagedOperation("dumps thread pool state")
-    public String dump()
-    {
-        return ContainerLifeCycle.dump(this);
-    }
-
     @Override
     public void dump(Appendable out, String indent) throws IOException
     {
@@ -585,14 +618,21 @@ public class QueuedThreadPool extends AbstractLifeCycle implements SizedThreadPo
         if (isDetailedDump())
             jobs = new ArrayList<>(getQueue());
 
-        ContainerLifeCycle.dumpObject(out, this);
+        dumpBeans(out, indent, threads, Collections.singletonList(new DumpableCollection("jobs", jobs)));
-        ContainerLifeCycle.dump(out, indent, threads, Collections.singletonList(new DumpableCollection("jobs",jobs)));
     }
 
     @Override
     public String toString()
     {
-        return String.format("QueuedThreadPool@%s{%s,%d<=%d<=%d,i=%d,q=%d}", _name, getState(), getMinThreads(), getThreads(), getMaxThreads(), getIdleThreads(), (_jobs == null ? -1 : _jobs.size()));
+        return String.format("QueuedThreadPool@%s{%s,%d<=%d<=%d,i=%d,q=%d,r=%s}", 
+            _name,
+            getState(),
+            getMinThreads(),
+            getThreads(),
+            getMaxThreads(),
+            getIdleThreads(),
+            _jobs.size(),
+            _tryExecutor);
     }
 
     private Runnable idleJobPoll() throws InterruptedException

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

@@ -42,7 +42,7 @@ import org.eclipse.jetty.util.log.Logger;
  * whenever it has been idle for that period.
  */
 @ManagedObject("A pool for reserved threads")
-public class ReservedThreadExecutor extends AbstractLifeCycle implements Executor
+public class ReservedThreadExecutor extends AbstractLifeCycle implements TryExecutor
 {
     private static final Logger LOG = Log.getLogger(ReservedThreadExecutor.class);
     private static final Runnable STOP = new Runnable()
@@ -66,42 +66,24 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
     private final AtomicInteger _pending = new AtomicInteger();
 
     private ThreadPoolBudget.Lease _lease;
-    private Object _owner;
     private long _idleTime = 1L;
     private TimeUnit _idleTimeUnit = TimeUnit.MINUTES;
 
-    public ReservedThreadExecutor(Executor executor)
-    {
-        this(executor,1);
-    }
-
-    /**
-     * @param executor The executor to use to obtain threads
-     * @param capacity The number of threads to preallocate. If less than 0 then capacity
-     * is calculated based on a heuristic from the number of available processors and
-     * thread pool size.
-     */
-    public ReservedThreadExecutor(Executor executor, int capacity)
-    {
-        this(executor,capacity,null);
-    }
-
     /**
      * @param executor The executor to use to obtain threads
      * @param capacity The number of threads to preallocate. If less than 0 then capacity
      *                 is calculated based on a heuristic from the number of available processors and
      *                 thread pool size.
-     * @param owner    the owner of the instance. Only used for debugging purpose withing the {@link #toString()} method
      */
-    public ReservedThreadExecutor(Executor executor,int capacity, Object owner)
+    public ReservedThreadExecutor(Executor executor,int capacity)
     {
         _executor = executor;
         _capacity = reservedThreads(executor,capacity);
         _stack = new ConcurrentLinkedDeque<>();
-        _owner = owner;
 
         LOG.debug("{}",this);
     }
+
     /**
      * @param executor The executor to use to obtain threads
      * @param capacity The number of threads to preallocate, If less than 0 then capacity
@@ -110,7 +92,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
      * @return the number of reserved threads that would be used by a ReservedThreadExecutor
      * constructed with these arguments.
      */
-    public static int reservedThreads(Executor executor,int capacity)
+    private static int reservedThreads(Executor executor,int capacity)
     {
         if (capacity>=0)
             return capacity;
@@ -118,7 +100,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
         if (executor instanceof ThreadPool.SizedThreadPool)
         {
             int threads = ((ThreadPool.SizedThreadPool)executor).getMaxThreads();
-            return Math.max(1, Math.min(cpus, threads / 8));
+            return Math.max(1, Math.min(cpus, threads / 10));
         }
         return cpus;
     }
@@ -193,8 +175,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
     @Override
     public void execute(Runnable task) throws RejectedExecutionException
     {
-        if (!tryExecute(task))
+        _executor.execute(task);
-            throw new RejectedExecutionException();
     }
 
     /**
@@ -255,13 +236,12 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
     @Override
     public String toString()
     {
-        return String.format("%s@%x{s=%d/%d,p=%d}@%s",
+        return String.format("%s@%x{s=%d/%d,p=%d}",
                 getClass().getSimpleName(),
                 hashCode(),
                 _size.get(),
                 _capacity,
-                _pending.get(),
+                _pending.get());
-                _owner);
     }
 
     private class ReservedThread implements Runnable

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

@@ -0,0 +1,72 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2018 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.util.thread;
+
+import java.util.concurrent.Executor;
+import java.util.concurrent.RejectedExecutionException;
+
+/** 
+ * A variation of Executor that can confirm if a thread is available immediately 
+ */
+public interface TryExecutor extends Executor
+{
+    /**
+     * Attempt to execute a task.
+     * @param task The task to be executed
+     * @return True IFF the task has been given directly to a thread to execute.  The task cannot be queued pending the later availability of a Thread. 
+     */
+    boolean tryExecute(Runnable task);
+    
+    default void execute(Runnable task)
+    {
+        if (!tryExecute(task))
+            throw new RejectedExecutionException();
+    }
+    
+    public static TryExecutor asTryExecutor(Executor executor)
+    {        
+        if (executor instanceof TryExecutor)
+            return (TryExecutor)executor;
+        return new NoTryExecutor(executor);
+    }
+
+    public static class NoTryExecutor implements TryExecutor
+    {
+        private final Executor executor;
+
+        public NoTryExecutor(Executor executor)
+        {
+            this.executor = executor;
+        }
+
+        @Override
+        public void execute(Runnable task)
+        {
+            executor.execute(task);
+        }
+
+        @Override
+        public boolean tryExecute(Runnable task)
+        {
+            return false;
+        }
+    }
+
+    public static final TryExecutor NO_TRY = task -> false;
+}

jetty-util/src/main/java/org/eclipse/jetty/util/thread/strategy/EatWhatYouKill.java

@@ -34,7 +34,7 @@ import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.thread.ExecutionStrategy;
 import org.eclipse.jetty.util.thread.Invocable;
 import org.eclipse.jetty.util.thread.Invocable.InvocationType;
-import org.eclipse.jetty.util.thread.ReservedThreadExecutor;
+import org.eclipse.jetty.util.thread.TryExecutor;
 
 /**
  * <p>A strategy where the thread that produces will run the resulting task if it
@@ -73,25 +73,16 @@ public class EatWhatYouKill extends ContainerLifeCycle implements ExecutionStrat
     private final LongAdder _executed = new LongAdder();
     private final Producer _producer;
     private final Executor _executor;
-    private final ReservedThreadExecutor _producers;
+    private final TryExecutor _tryExecutor;
     private State _state = State.IDLE;
 
     public EatWhatYouKill(Producer producer, Executor executor)
-    {
-        this(producer,executor,new ReservedThreadExecutor(executor,1));
-    }
-
-    public EatWhatYouKill(Producer producer, Executor executor, int maxReserved)
-    {
-        this(producer,executor,new ReservedThreadExecutor(executor,maxReserved));
-    }
-
-    public EatWhatYouKill(Producer producer, Executor executor, ReservedThreadExecutor producers)
     {
         _producer = producer;
         _executor = executor;
-        _producers = producers;
+        _tryExecutor = TryExecutor.asTryExecutor(executor);
         addBean(_producer);
+        addBean(_tryExecutor);
         if (LOG.isDebugEnabled())
             LOG.debug("{} created", this);        
     }
@@ -214,7 +205,7 @@ public class EatWhatYouKill extends ContainerLifeCycle implements ExecutionStrat
                 {
                     synchronized(this)
                     {
-                        if (_producers.tryExecute(this))
+                        if (_tryExecutor.tryExecute(this))
                         {
                             // EXECUTE PRODUCE CONSUME!
                             // We have executed a new Producer, so we can EWYK consume
@@ -334,7 +325,7 @@ public class EatWhatYouKill extends ContainerLifeCycle implements ExecutionStrat
     {
         builder.append(_state);
         builder.append('/');
-        builder.append(_producers);
+        builder.append(_tryExecutor);
         builder.append("[nb=");
         builder.append(getNonBlockingTasksConsumed());
         builder.append(",c=");