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Fixes #1805 - ReservedThreadExecutor should start ReservedThreads lazily. 

Removed doStart() that was eagerly starting ReservedThreads.
Other small code cleanups.
This commit is contained in:
Simone Bordet 2017-09-08 10:27:36 +02:00
parent 5d8c605d96
commit c1a4153861
1 changed files with 33 additions and 46 deletions
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79
jetty-util/src/main/java/org/eclipse/jetty/util/thread/ReservedThreadExecutor.java
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@ -38,14 +38,14 @@ import org.eclipse.jetty.util.log.Logger;
public class ReservedThreadExecutor extends AbstractLifeCycle implements Executor
{
private static final Logger LOG = Log.getLogger(ReservedThreadExecutor.class);
private final Executor _executor;
private final Locker _locker = new Locker();
private final ReservedThread[] _queue;
private int _head;
private int _size;
private int _pending;
public ReservedThreadExecutor(Executor executor)
{
this(executor,1);
@ -54,7 +54,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
/**
* @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
* is calculated based on a heuristic from the number of available processors and
* thread pool size.
*/
public ReservedThreadExecutor(Executor executor,int capacity)
@ -74,7 +74,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
capacity = cpus;
}
}
_queue = new ReservedThread[capacity];
}
@ -106,21 +106,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
return _pending;
}
}
@Override
public void doStart() throws Exception
{
try (Locker.Lock lock = _locker.lock())
{
_head = _size = _pending = 0;
while (_pending<_queue.length)
{
_executor.execute(new ReservedThread());
_pending++;
}
}
}
@Override
public void doStop() throws Exception
{
@ -135,15 +121,15 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
thread._wakeup.signal();
}
}
}
}
@Override
public void execute(Runnable task) throws RejectedExecutionException
{
if (!tryExecute(task))
throw new RejectedExecutionException();
}
/**
* @param task The task to run
* @return True iff a reserved thread was available and has been assigned the task to run.
@ -152,7 +138,7 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
{
if (task==null)
return false;
try (Locker.Lock lock = _locker.lock())
{
if (_size==0)
@ -164,21 +150,21 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
}
return false;
}
ReservedThread thread = _queue[_head];
_queue[_head] = null;
_head = (_head+1)%_queue.length;
_size--;
if (_size==0 && _pending<_queue.length)
{
_executor.execute(new ReservedThread());
_pending++;
}
thread._task = task;
thread._wakeup.signal();
return true;
}
catch(RejectedExecutionException e)
@ -188,23 +174,31 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
}
}
@Override
public String toString()
{
try (Locker.Lock lock = _locker.lock())
{
return String.format("%s{s=%d,p=%d}",super.toString(),_size,_pending);
}
}
private class ReservedThread implements Runnable
{
private Condition _wakeup = null;
private Runnable _task = null;
private void reservedWait() throws InterruptedException
{
_wakeup.await();
}
@Override
public void run()
{
while (true)
{
Runnable task = null;
try (Locker.Lock lock = _locker.lock())
{
// if this is our first loop, decrement pending count
@ -213,20 +207,24 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
_pending--;
_wakeup = _locker.newCondition();
}
// Exit if no longer running or there now too many preallocated threads
if (!isRunning() || _size>=_queue.length)
break;
// Insert ourselves in the queue
_queue[(_head+_size++)%_queue.length] = this;
// Wait for a task, ignoring spurious interrupts
do
// Wait for a task, ignoring spurious wakeups
while (isRunning() && task==null)
{
try
{
if (LOG.isDebugEnabled())
LOG.debug("{} waiting", this);
reservedWait();
if (LOG.isDebugEnabled())
LOG.debug("{} woken up", this);
task = _task;
_task = null;
}
@ -235,7 +233,6 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
LOG.ignore(e);
}
}
while (isRunning() && task==null);
}
// Run any task
@ -245,22 +242,12 @@ public class ReservedThreadExecutor extends AbstractLifeCycle implements Executo
{
task.run();
}
catch (Exception e)
catch (Throwable e)
{
LOG.warn(e);
break;
}
}
}
}
}
@Override
public String toString()
{
try (Locker.Lock lock = _locker.lock())
{
return String.format("%s{s=%d,p=%d}",super.toString(),_size,_pending);
}
}
}