Fixes #12289 - Improve ConcurrentPool concurrency. (#12290)

A call to `sweep()`, although protected by the lock for concurrent calls to `reserve()`, may be concurrent with `remove(Entry)`.

`remove(Entry)` in turn calls `entries.remove(Object)`, so that the concurrent iteration in `sweep()` over `entries` fails with an `ArrayIndexOutOfBoundsException`.

Now using the bulk `entries.removeIf(Predicate)` method in `sweep()`, so that sweeping is atomic with respect to `entries.remove(Object)`.

Fixed other occurrences of manual iteration over CopyOnWriteArrayList that may be concurrent with removals.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
This commit is contained in:
Simone Bordet 2024-09-20 16:50:39 +03:00 committed by GitHub
parent 9c342637cc
commit 115ee1cf39
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7 changed files with 48 additions and 36 deletions

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@ -653,11 +653,11 @@ public class ContextHandler extends Handler.Wrapper implements Attributes, Alias
*/
protected void notifyExitScope(Request request)
{
for (int i = _contextListeners.size(); i-- > 0; )
for (ContextScopeListener listener : TypeUtil.reverse(_contextListeners))
{
try
{
_contextListeners.get(i).exitScope(_context, request);
listener.exitScope(_context, request);
}
catch (Throwable e)
{

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@ -87,7 +87,7 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
* @param cache whether a {@link ThreadLocal} cache should be used for the most recently released entry
* @deprecated cache is no longer supported. Use {@link StrategyType#THREAD_ID}
*/
@Deprecated
@Deprecated(since = "12.0.4", forRemoval = true)
public ConcurrentPool(StrategyType strategyType, int maxSize, boolean cache)
{
this(strategyType, maxSize, pooled -> 1);
@ -103,7 +103,7 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
* @param maxMultiplex a function that given the pooled object returns the max multiplex count
* @deprecated cache is no longer supported. Use {@link StrategyType#THREAD_ID}
*/
@Deprecated
@Deprecated(since = "12.0.4", forRemoval = true)
public ConcurrentPool(StrategyType strategyType, int maxSize, boolean cache, ToIntFunction<P> maxMultiplex)
{
this(strategyType, maxSize, maxMultiplex);
@ -148,7 +148,7 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
{
leaked.increment();
if (LOG.isDebugEnabled())
LOG.debug("Leaked " + holder);
LOG.debug("Leaked {}", holder);
leaked();
}
@ -195,15 +195,14 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
void sweep()
{
for (int i = 0; i < entries.size(); i++)
// Remove entries atomically with respect to remove(Entry).
entries.removeIf(holder ->
{
Holder<P> holder = entries.get(i);
if (holder.getEntry() == null)
{
entries.remove(i--);
boolean remove = holder.getEntry() == null;
if (remove)
leaked(holder);
}
}
return remove;
});
}
@Override
@ -285,8 +284,7 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
if (!removed)
return false;
// No need to lock, no race with reserve()
// and the race with terminate() is harmless.
// In a harmless race with reserve()/sweep()/terminate().
Holder<P> holder = ((ConcurrentEntry<P>)entry).getHolder();
boolean evicted = entries.remove(holder);
if (LOG.isDebugEnabled())
@ -313,10 +311,7 @@ public class ConcurrentPool<P> implements Pool<P>, Dumpable
// Field this.terminated must be modified with the lock held
// because the list of entries is modified, see reserve().
terminated = true;
copy = entries.stream()
.map(Holder::getEntry)
.filter(Objects::nonNull)
.toList();
copy = stream().toList();
entries.clear();
}

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@ -173,6 +173,21 @@ public class TypeUtil
return Arrays.asList(a);
}
/**
* <p>Returns a new list with the elements of the specified list in reverse order.</p>
* <p>The specified list is not modified, differently from {@link Collections#reverse(List)}.</p>
*
* @param list the list whose elements are to be reversed
* @return a new list with the elements in reverse order
* @param <T> the element type
*/
public static <T> List<T> reverse(List<T> list)
{
List<T> result = new ArrayList<>(list);
Collections.reverse(result);
return result;
}
/**
* Class from a canonical name for a type.
*

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@ -95,6 +95,7 @@ import org.eclipse.jetty.util.DeprecationWarning;
import org.eclipse.jetty.util.ExceptionUtil;
import org.eclipse.jetty.util.Loader;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.TypeUtil;
import org.eclipse.jetty.util.URIUtil;
import org.eclipse.jetty.util.annotation.ManagedAttribute;
import org.eclipse.jetty.util.annotation.ManagedObject;
@ -518,8 +519,7 @@ public class ServletContextHandler extends ContextHandler
//Call context listeners
Throwable multiException = null;
ServletContextEvent event = new ServletContextEvent(getServletContext());
Collections.reverse(_destroyServletContextListeners);
for (ServletContextListener listener : _destroyServletContextListeners)
for (ServletContextListener listener : TypeUtil.reverse(_destroyServletContextListeners))
{
try
{
@ -574,17 +574,17 @@ public class ServletContextHandler extends ContextHandler
if (!_servletRequestListeners.isEmpty())
{
final ServletRequestEvent sre = new ServletRequestEvent(getServletContext(), request);
for (int i = _servletRequestListeners.size(); i-- > 0; )
for (ServletRequestListener listener : TypeUtil.reverse(_servletRequestListeners))
{
_servletRequestListeners.get(i).requestDestroyed(sre);
listener.requestDestroyed(sre);
}
}
if (!_servletRequestAttributeListeners.isEmpty())
{
for (int i = _servletRequestAttributeListeners.size(); i-- > 0; )
for (ServletRequestAttributeListener listener : TypeUtil.reverse(_servletRequestAttributeListeners))
{
scopedRequest.removeEventListener(_servletRequestAttributeListeners.get(i));
scopedRequest.removeEventListener(listener);
}
}
}
@ -1223,11 +1223,11 @@ public class ServletContextHandler extends ContextHandler
ServletContextRequest scopedRequest = Request.as(request, ServletContextRequest.class);
if (!_contextListeners.isEmpty())
{
for (int i = _contextListeners.size(); i-- > 0; )
for (ServletContextScopeListener listener : TypeUtil.reverse(_contextListeners))
{
try
{
_contextListeners.get(i).exitScope(getContext(), scopedRequest);
listener.exitScope(getContext(), scopedRequest);
}
catch (Throwable e)
{

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@ -47,6 +47,7 @@ import org.eclipse.jetty.session.AbstractSessionManager;
import org.eclipse.jetty.session.ManagedSession;
import org.eclipse.jetty.session.SessionConfig;
import org.eclipse.jetty.util.Callback;
import org.eclipse.jetty.util.TypeUtil;
public class SessionHandler extends AbstractSessionManager implements Handler.Singleton
{
@ -569,9 +570,9 @@ public class SessionHandler extends AbstractSessionManager implements Handler.Si
getSessionContext().run(() ->
{
HttpSessionEvent event = new HttpSessionEvent(session.getApi());
for (int i = _sessionListeners.size() - 1; i >= 0; i--)
for (HttpSessionListener listener : TypeUtil.reverse(_sessionListeners))
{
_sessionListeners.get(i).sessionDestroyed(event);
listener.sessionDestroyed(event);
}
});
}

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@ -1000,17 +1000,17 @@ public class ContextHandler extends ScopedHandler implements Attributes, Supplie
if (!_servletRequestListeners.isEmpty())
{
final ServletRequestEvent sre = new ServletRequestEvent(_apiContext, request);
for (int i = _servletRequestListeners.size(); i-- > 0; )
for (ServletRequestListener listener : TypeUtil.reverse(_servletRequestListeners))
{
_servletRequestListeners.get(i).requestDestroyed(sre);
listener.requestDestroyed(sre);
}
}
if (!_servletRequestAttributeListeners.isEmpty())
{
for (int i = _servletRequestAttributeListeners.size(); i-- > 0; )
for (ServletRequestAttributeListener listener : TypeUtil.reverse(_servletRequestAttributeListeners))
{
baseRequest.removeEventListener(_servletRequestAttributeListeners.get(i));
baseRequest.removeEventListener(listener);
}
}
}
@ -1070,11 +1070,11 @@ public class ContextHandler extends ScopedHandler implements Attributes, Supplie
{
if (!_contextListeners.isEmpty())
{
for (int i = _contextListeners.size(); i-- > 0; )
for (ContextScopeListener listener : TypeUtil.reverse(_contextListeners))
{
try
{
_contextListeners.get(i).exitScope(_apiContext, request);
listener.exitScope(_apiContext, request);
}
catch (Throwable e)
{

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@ -54,6 +54,7 @@ import org.eclipse.jetty.session.SessionIdManager;
import org.eclipse.jetty.session.SessionManager;
import org.eclipse.jetty.util.Callback;
import org.eclipse.jetty.util.StringUtil;
import org.eclipse.jetty.util.TypeUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@ -834,9 +835,9 @@ public class SessionHandler extends ScopedHandler implements SessionConfig.Mutab
Runnable r = () ->
{
HttpSessionEvent event = new HttpSessionEvent(session.getApi());
for (int i = _sessionListeners.size() - 1; i >= 0; i--)
for (HttpSessionListener listener : TypeUtil.reverse(_sessionListeners))
{
_sessionListeners.get(i).sessionDestroyed(event);
listener.sessionDestroyed(event);
}
};
_contextHandler.getCoreContextHandler().getContext().run(r);