我本质上张贴的tomcat-users邮件列表上同样的问题，并在Tomcat的Bugzilla的一些信息沿着这个响应（[43866]）使我得出以下结论：
- 有没有等同于useDirtyFlag，如果您在会话中放置可变（即更改）的对象，则需要定制代码解决方案。
- Tomcat ClusterValve似乎是这个解决方案的一个有效位置 - 插入到集群机制中，操纵属性使DeltaManager管理器看起来会话中的所有属性都发生了变化。这迫使整个会话的复制。
步骤1：写ForceReplicationValve（延伸ValveBase器具ClusterValve）
我将不包括整个类，但逻辑的键位（取出记录和的instanceof检查）：
@Override
public void invoke(Request request, Response response)
throws IOException, ServletException {
getNext().invoke(request, response);
Session session = request.getSessionInternal();
HttpSession deltaSession = (HttpSession) session;
for (Enumeration<String> names = deltaSession.getAttributeNames();
names.hasMoreElements();) {
String name = names.nextElement();
deltaSession.setAttribute(name, deltaSession.getAttribute(name));
}
}
步骤2：改变集群配置（在conf/server.xml）
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
channelSendOptions="8">
<Valve className="org.apache.catalina.ha.tcp.ForceReplicationValve"/>
<Valve className="org.apache.catalina.ha.tcp.ReplicationValve"
filter=".*\.gif;.*\.jpg;.*\.png;.*\.js;.*\.htm;.*\.html;.*\.txt;.*\.css;"/>
<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
<ClusterListener className="org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener"/>
<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>
会话到所有集群节点的复制现在将发生在每个请求之后。
另外：请注意channelSendOptions设置。这将从Tomcat 5.0.x中取代replicationMode=asynchronous/synchronous/pooled。有关可能的int值，请参见cluster documentation。
附录：全阀源的要求
package org.apache.catalina.ha.tcp;
import java.io.IOException;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;
import org.apache.catalina.Lifecycle;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleListener;
import org.apache.catalina.Session;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.ha.CatalinaCluster;
import org.apache.catalina.ha.ClusterValve;
import org.apache.catalina.ha.session.ReplicatedSession;
import org.apache.catalina.ha.session.SimpleTcpReplicationManager;
import org.apache.catalina.util.LifecycleSupport;
//import org.apache.catalina.util.StringManager;
import org.apache.catalina.valves.ValveBase;
/**
* <p>With the {@link SimpleTcpReplicationManager} effectively deprecated, this allows
* mutable objects to be replicated in the cluster by forcing the "dirty" status on
* every request.</p>
*
* @author Jon Brisbin (via post on tomcat-users http://markmail.org/thread/rdo3drcir75dzzrq)
* @author Kevin Jansz
*/
public class ForceReplicationValve extends ValveBase implements Lifecycle, ClusterValve {
private static org.apache.juli.logging.Log log =
org.apache.juli.logging.LogFactory.getLog(ForceReplicationValve.class);
@SuppressWarnings("hiding")
protected static final String info = "org.apache.catalina.ha.tcp.ForceReplicationValve/1.0";
// this could be used if ForceReplicationValve messages were setup
// in org/apache/catalina/ha/tcp/LocalStrings.properties
//
// /**
// * The StringManager for this package.
// */
// @SuppressWarnings("hiding")
// protected static StringManager sm =
// StringManager.getManager(Constants.Package);
/**
* Not actually required but this must implement {@link ClusterValve} to
* be allowed to be added to the Cluster.
*/
private CatalinaCluster cluster = null ;
/**
* Also not really required, implementing {@link Lifecycle} to allow
* initialisation and shutdown to be logged.
*/
protected LifecycleSupport lifecycle = new LifecycleSupport(this);
/**
* Default constructor
*/
public ForceReplicationValve() {
super();
if (log.isInfoEnabled()) {
log.info(getInfo() + ": created");
}
}
@Override
public String getInfo() {
return info;
}
@Override
public void invoke(Request request, Response response) throws IOException,
ServletException {
getNext().invoke(request, response);
Session session = null;
try {
session = request.getSessionInternal();
} catch (Throwable e) {
log.error(getInfo() + ": Unable to perform replication request.", e);
}
String context = request.getContext().getName();
String task = request.getPathInfo();
if(task == null) {
task = request.getRequestURI();
}
if (session != null) {
if (log.isDebugEnabled()) {
log.debug(getInfo() + ": [session=" + session.getId() + ", instanceof=" + session.getClass().getName() + ", context=" + context + ", request=" + task + "]");
}
if (session instanceof ReplicatedSession) {
// it's a SimpleTcpReplicationManager - can just set to dirty
((ReplicatedSession) session).setIsDirty(true);
if (log.isDebugEnabled()) {
log.debug(getInfo() + ": [session=" + session.getId() + ", context=" + context + ", request=" + task + "] maked DIRTY");
}
} else {
// for everything else - cycle all attributes
List cycledNames = new LinkedList();
// in a cluster where the app is <distributable/> this should be
// org.apache.catalina.ha.session.DeltaSession - implements HttpSession
HttpSession deltaSession = (HttpSession) session;
for (Enumeration<String> names = deltaSession.getAttributeNames(); names.hasMoreElements();) {
String name = names.nextElement();
deltaSession.setAttribute(name, deltaSession.getAttribute(name));
cycledNames.add(name);
}
if (log.isDebugEnabled()) {
log.debug(getInfo() + ": [session=" + session.getId() + ", context=" + context + ", request=" + task + "] cycled atrributes=" + cycledNames + "");
}
}
} else {
String id = request.getRequestedSessionId();
log.warn(getInfo() + ": [session=" + id + ", context=" + context + ", request=" + task + "] Session not available, unable to send session over cluster.");
}
}
/*
* ClusterValve methods - implemented to ensure this valve is not ignored by Cluster
*/
public CatalinaCluster getCluster() {
return cluster;
}
public void setCluster(CatalinaCluster cluster) {
this.cluster = cluster;
}
/*
* Lifecycle methods - currently implemented just for logging startup
*/
/**
* Add a lifecycle event listener to this component.
*
* @param listener The listener to add
*/
public void addLifecycleListener(LifecycleListener listener) {
lifecycle.addLifecycleListener(listener);
}
/**
* Get the lifecycle listeners associated with this lifecycle. If this
* Lifecycle has no listeners registered, a zero-length array is returned.
*/
public LifecycleListener[] findLifecycleListeners() {
return lifecycle.findLifecycleListeners();
}
/**
* Remove a lifecycle event listener from this component.
*
* @param listener The listener to remove
*/
public void removeLifecycleListener(LifecycleListener listener) {
lifecycle.removeLifecycleListener(listener);
}
public void start() throws LifecycleException {
lifecycle.fireLifecycleEvent(START_EVENT, null);
if (log.isInfoEnabled()) {
log.info(getInfo() + ": started");
}
}
public void stop() throws LifecycleException {
lifecycle.fireLifecycleEvent(STOP_EVENT, null);
if (log.isInfoEnabled()) {
log.info(getInfo() + ": stopped");
}
}
}
的[如何对网页（http://tomcat.apache.org/tomcat-6.0-doc/cluster- howto.html）说：“对于每个请求整个会话都被复制，这允许修改会话中的属性而不调用setAttribute或removeAttribute的代码”。这不正常吗？或者我误解了问题/答案？ – 2011-10-20 09:28:09
看来这条评论是在我发布这个问题之后添加的......它还说“useDirtyFlag配置参数可用于优化会话复制的次数”。这意味着默认情况下有'useDirtyFlag'关闭/ false。我看不到任何参考文献（在文档或代码中）来确认这一点 - 我自己的测试（去年）没有得到这种行为。 – kevinjansz 2011-10-23 22:45:09
它看起来像Tomcat文档中的错误。 – fglez 2012-11-29 17:53:41