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Issue #547 EWYK leaves low resource mode 

Directly implement PEC in EPC low resource mode
This commit is contained in:
Greg Wilkins 2016-05-05 10:42:08 +10:00
parent e6e63d5549
commit 6591137ba0
5 changed files with 122 additions and 77 deletions
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1
jetty-server/src/test/java/org/eclipse/jetty/server/ThreadStarvationTest.java
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@ -139,7 +139,6 @@ public class ThreadStarvationTest extends HttpServerTestFixture
assertThat(response,containsString("200 OK"));
assertThat(response,containsString("Read Input 10"));
}
}

3
jetty-util/src/main/java/org/eclipse/jetty/util/thread/ExecutionStrategy.java
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@ -79,7 +79,8 @@ public interface ExecutionStrategy
*/
Runnable produce();
}
/**
* <p>A factory for {@link ExecutionStrategy}.</p>
*/

104
jetty-util/src/main/java/org/eclipse/jetty/util/thread/strategy/ExecuteProduceConsume.java
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@ -43,32 +43,30 @@ import org.eclipse.jetty.util.thread.ThreadPool;
* pressure on producers.
* </p>
*/
public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
public class ExecuteProduceConsume extends ExecutingExecutionStrategy implements ExecutionStrategy, Runnable
{
private static final Logger LOG = Log.getLogger(ExecuteProduceConsume.class);
private final Locker _locker = new Locker();
private final Runnable _runExecute = new RunExecute();
private final Producer _producer;
private final Executor _executor;
private boolean _idle=true;
private boolean _execute;
private boolean _producing;
private boolean _pending;
private final ThreadPool _threadpool;
private final ExecutionStrategy _lowresources;
public ExecuteProduceConsume(Producer producer, Executor executor)
{
this(producer,executor,(executor instanceof ThreadPool)?new ProduceExecuteConsume(producer,executor):null);
super(executor);
this._producer = producer;
_threadpool = (executor instanceof ThreadPool)?((ThreadPool)executor):null;
}
@Deprecated
public ExecuteProduceConsume(Producer producer, Executor executor, ExecutionStrategy lowResourceStrategy)
{
this._producer = producer;
this._executor = executor;
_threadpool = (executor instanceof ThreadPool)?((ThreadPool)executor):null;
_lowresources = _threadpool==null?null:lowResourceStrategy;
this(producer,executor);
}
@Override
@ -100,7 +98,7 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
}
if (produce)
produceAndRun();
produceConsume();
}
@Override
@ -117,7 +115,7 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
_execute=true;
}
if (dispatch)
_executor.execute(_runExecute);
execute(_runExecute);
}
@Override
@ -137,28 +135,50 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
if (produce)
{
// If we are low on resources, then switch to PEC strategy which does not
// suffer as badly from thread starvation
while (_threadpool!=null && _threadpool.isLowOnThreads())
{
LOG.debug("EPC low resources {}",this);
try
{
_lowresources.execute();
}
catch(Throwable e)
{
// just warn if lowresources execute fails and keep producing
LOG.warn(e);
}
}
// If we are low on threads, this could be the last thread, so we must not consume.
// So call produceExecuteConsume instead
if (_threadpool!=null && _threadpool.isLowOnThreads() && !produceExecuteConsume())
return;
// no longer low resources so produceAndRun normally
produceAndRun();
produceConsume();
}
}
private void produceAndRun()
/**
* @return true if we are still producing
*/
private boolean produceExecuteConsume()
{
if (LOG.isDebugEnabled())
LOG.debug("{} Low Resources",this);
while (_threadpool.isLowOnThreads())
{
Runnable task = _producer.produce();
if (LOG.isDebugEnabled())
LOG.debug("{} produced {}", _producer, task);
if (task == null)
{
// No task, so we are now idle
try (Lock locked = _locker.lock())
{
if (LOG.isDebugEnabled())
LOG.debug("{} Idle Low Resources",this);
_producing=false;
_idle=false;
}
return false;
}
// Execute the task.
execute(task);
}
if (LOG.isDebugEnabled())
LOG.debug("{} No longer Low Resources",this);
return true;
}
private void produceConsume()
{
if (LOG.isDebugEnabled())
LOG.debug("{} produce enter",this);
@ -184,6 +204,7 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
if (task == null)
{
// There is no task.
// Could another one just have been queued with an execute?
if (_execute)
{
_idle=false;
@ -214,30 +235,8 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
// Spawn a new thread to continue production by running the produce loop.
if (LOG.isDebugEnabled())
LOG.debug("{} dispatch",this);
try
{
_executor.execute(this);
}
catch(RejectedExecutionException e)
{
// If we cannot execute, then discard/reject the task and keep producing
LOG.debug(e);
LOG.warn("RejectedExecution {}",task);
try
{
if (task instanceof Rejectable)
((Rejectable)task).reject();
}
catch (Exception x)
{
e.addSuppressed(x);
LOG.warn(e);
}
finally
{
task=null;
}
}
if (!execute(this))
task=null;
}
// Run the task.
@ -262,6 +261,7 @@ public class ExecuteProduceConsume implements ExecutionStrategy, Runnable
LOG.debug("{} produce exit",this);
}
public Boolean isIdle()
{
try (Lock locked = _locker.lock())

65
jetty-util/src/main/java/org/eclipse/jetty/util/thread/strategy/ExecutingExecutionStrategy.java Normal file
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@ -0,0 +1,65 @@
//
// ========================================================================
// Copyright (c) 1995-2016 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.strategy;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
import org.eclipse.jetty.util.thread.ExecutionStrategy;
public abstract class ExecutingExecutionStrategy implements ExecutionStrategy
{
private static final Logger LOG = Log.getLogger(ExecutingExecutionStrategy.class);
private final Executor _executor;
protected ExecutingExecutionStrategy(Executor executor)
{
_executor=executor;
}
protected boolean execute(Runnable task)
{
try
{
_executor.execute(task);
return true;
}
catch(RejectedExecutionException e)
{
// If we cannot execute, then discard/reject the task and keep producing
LOG.debug(e);
LOG.warn("RejectedExecution {}",task);
try
{
if (task instanceof Rejectable)
((Rejectable)task).reject();
}
catch (Exception x)
{
e.addSuppressed(x);
LOG.warn(e);
}
}
return false;
}
}

26
jetty-util/src/main/java/org/eclipse/jetty/util/thread/strategy/ProduceExecuteConsume.java
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@ -29,18 +29,17 @@ import org.eclipse.jetty.util.thread.ExecutionStrategy;
* <p>A strategy where the caller thread iterates over task production, submitting each
* task to an {@link Executor} for execution.</p>
*/
public class ProduceExecuteConsume implements ExecutionStrategy
public class ProduceExecuteConsume extends ExecutingExecutionStrategy implements ExecutionStrategy
{
private static final Logger LOG = Log.getLogger(ProduceExecuteConsume.class);
private final Producer _producer;
private final Executor _executor;
private State _state = State.IDLE;
public ProduceExecuteConsume(Producer producer, Executor executor)
{
super(executor);
this._producer = producer;
this._executor = executor;
}
@Override
@ -73,26 +72,7 @@ public class ProduceExecuteConsume implements ExecutionStrategy
}
// Execute the task.
try
{
_executor.execute(task);
}
catch (RejectedExecutionException e)
{
// Discard/reject tasks that cannot be executed
if (task instanceof Rejectable)
{
try
{
((Rejectable)task).reject();
}
catch (Throwable x)
{
e.addSuppressed(x);
LOG.warn(e);
}
}
}
execute(task);
}
}