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作为一个BI开发人员,我要发布报表,元数据,OLAP的模型到BI服务器
看完tomcat的源码,迫不及待的想研究下tomcat集群,可惜,网络上对于tomcat集群的源码分析比较少(百度,google都找了,基本没有,只有api),基本上都是讲些tomcat集群的配置,以及粗浅的东西,无奈之下,硬着头皮看代码,做个笔记记录下。
首先在StandardEngine(ContainerBase).start()方法中,对集群进行启动
if ((cluster != null) && (cluster instanceof Lifecycle)) ((Lifecycle) cluster).start();
下面是集群启动的方法:
public void start() throws LifecycleException { if (started) throw new LifecycleException(sm.getString("cluster.alreadyStarted")); if (log.isInfoEnabled()) log.info("Cluster is about to start"); // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, this); try { checkDefaults(); // 检查默认配置 registerClusterValve(); channel.addMembershipListener(this); channel.addChannelListener(this); channel.start(channelStartOptions); if (clusterDeployer != null) clusterDeployer.start(); this.started = true; // Notify our interested LifecycleListeners lifecycle.fireLifecycleEvent(AFTER_START_EVENT, this); } catch (Exception x) { log.error("Unable to start cluster.", x); throw new LifecycleException(x); } }
checkDefaults();
protected void checkDefaults() { if ( clusterListeners.size() == 0 ) { addClusterListener(new JvmRouteSessionIDBinderListener()); addClusterListener(new ClusterSessionListener()); } if ( valves.size() == 0 ) { addValve(new JvmRouteBinderValve()); addValve(new ReplicationValve()); } if ( clusterDeployer != null ) clusterDeployer.setCluster(this); if ( channel == null ) channel = new GroupChannel(); if ( channel instanceof GroupChannel && !((GroupChannel)channel).getInterceptors().hasNext()) { channel.addInterceptor(new MessageDispatch15Interceptor()); channel.addInterceptor(new TcpFailureDetector()); } }
相当于:
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="6"> <Manager className="org.apache.catalina.ha.session.BackupManager" expireSessionsOnShutdown="false" notifyListenersOnReplication="true" mapSendOptions="6" /> <Channel className="org.apache.catalina.tribes.group.GroupChannel"> <Membership className="org.apache.catalina.tribes.membership.McastService" address="228.0.0.4" port="45564" frequency="500" dropTime="3000" /> <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver" address="auto" port="5000" selectorTimeout="100" maxThreads="6" /> <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter"> <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender" /> </Sender> <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector" /> <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor" /> <Interceptor className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor" /> </Channel> <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" filter=".*\.gif;.*\.js;.*\.jpg;.*\.png;.*\.htm;.*\.html;.*\.css;.*\.txt;" /> <Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer" tempDir="/tmp/war-temp/" deployDir="/tmp/war-deploy/" watchDir="/tmp/war-listen/" watchEnabled="false" /> <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener" /> </Cluster>
registerClusterValve();
protected void registerClusterValve() throws Exception { if(container != null ) { for (Iterator iter = valves.iterator(); iter.hasNext();) { ClusterValve valve = (ClusterValve) iter.next(); if (log.isDebugEnabled()) log.debug("Invoking addValve on " + getContainer() + " with class=" + valve.getClass().getName()); if (valve != null) { // 将value存放到Engine的values中,请求时,通过管道pipeline进行调用。 IntrospectionUtils.callMethodN(getContainer(), "addValve", new Object[] { valve }, new Class[] { org.apache.catalina.Valve.class }); } valve.setCluster(this); } } }
接下来,看看通道的启动:
channel.start(channelStartOptions); channelStartOptions默认为15,二进制位1111.
public synchronized void start(int svc) throws ChannelException { setupDefaultStack(); if (optionCheck) checkOptionFlags(); super.start(svc); if ( hbthread == null && heartbeat ) { hbthread = new HeartbeatThread(this,heartbeatSleeptime); hbthread.start(); } }
首先调用父类的start方法,super.start(svc);
一层一层的调用,最后调用
/** * Starts up the channel. This can be called multiple times for individual services to start * The svc parameter can be the logical or value of any constants * @param svc int value of <BR> * DEFAULT - will start all services <BR> * MBR_RX_SEQ - starts the membership receiver <BR> * MBR_TX_SEQ - starts the membership broadcaster <BR> * SND_TX_SEQ - starts the replication transmitter<BR> * SND_RX_SEQ - starts the replication receiver<BR> * @throws ChannelException if a startup error occurs or the service is already started. */ protected synchronized void internalStart(int svc) throws ChannelException { try { boolean valid = false; //make sure we don't pass down any flags that are unrelated to the bottom layer svc = svc & Channel.DEFAULT; if (startLevel == Channel.DEFAULT) return; //we have already started up all components if (svc == 0 ) return;//nothing to start if (svc == (svc & startLevel)) throw new ChannelException("Channel already started for level:"+svc); //must start the receiver first so that we can coordinate the port it //listens to with the local membership settings if ( Channel.SND_RX_SEQ==(svc & Channel.SND_RX_SEQ) ) { clusterReceiver.setMessageListener(this); clusterReceiver.start(); //synchronize, big time FIXME membershipService.setLocalMemberProperties(getClusterReceiver().getHost(), getClusterReceiver().getPort()); valid = true; } if ( Channel.SND_TX_SEQ==(svc & Channel.SND_TX_SEQ) ) { clusterSender.start(); valid = true; } if ( Channel.MBR_RX_SEQ==(svc & Channel.MBR_RX_SEQ) ) { membershipService.setMembershipListener(this); membershipService.start(MembershipService.MBR_RX); valid = true; } if ( Channel.MBR_TX_SEQ==(svc & Channel.MBR_TX_SEQ) ) { membershipService.start(MembershipService.MBR_TX); valid = true; } if ( !valid) { throw new IllegalArgumentException("Invalid start level, valid levels are:SND_RX_SEQ,SND_TX_SEQ,MBR_TX_SEQ,MBR_RX_SEQ"); } startLevel = (startLevel | svc); }catch ( ChannelException cx ) { throw cx; }catch ( Exception x ) { throw new ChannelException(x); } }
上面的代码,英文注释也比较清楚,我就不画蛇添足再做解释了。
接下来就是:
if ( hbthread == null && heartbeat ) { hbthread = new HeartbeatThread(this,heartbeatSleeptime); hbthread.start(); }
启动
super.heartbeat(); Iterator i = membershipListeners.iterator(); while ( i.hasNext() ) { Object o = i.next(); if ( o instanceof Heartbeat ) ((Heartbeat)o).heartbeat(); } i = channelListeners.iterator(); while ( i.hasNext() ) { Object o = i.next(); if ( o instanceof Heartbeat ) ((Heartbeat)o).heartbeat(); }
super.heartbeat();
super.heartbeat(); checkMembers(false);
checkMembers(boolean checkAll)
public void checkMembers(boolean checkAll) { try { if (membership == null) setupMembership(); synchronized (membership) { if ( !checkAll ) performBasicCheck(); else performForcedCheck(); } }catch ( Exception x ) { log.warn("Unable to perform heartbeat on the TcpFailureDetector.",x); } finally { } }
performBasicCheck()
protected void performBasicCheck() { //update all alive times Member[] members = super.getMembers(); for (int i = 0; members != null && i < members.length; i++) { if (membership.memberAlive( (MemberImpl) members[i])) { // 更新当前的节点的最近心跳时间戳lastHeardFrom。 //we don't have this one in our membership, check to see if he/she is alive if (memberAlive(members[i])) { log.warn("Member added, even though we werent notified:" + members[i]); super.memberAdded(members[i]); } else { membership.removeMember( (MemberImpl) members[i]); } //end if } //end if } //for //check suspect members if they are still alive, //if not, simply issue the memberDisappeared message MemberImpl[] keys = (MemberImpl[]) removeSuspects.keySet().toArray(new MemberImpl[removeSuspects.size()]); for (int i = 0; i < keys.length; i++) { MemberImpl m = (MemberImpl) keys[i]; if (membership.getMember(m) != null && (!memberAlive(m))) { membership.removeMember(m); super.memberDisappeared(m); removeSuspects.remove(m); if(log.isInfoEnabled()) log.info("Suspect member, confirmed dead.["+m+"]"); } //end if } //check add suspects members if they are alive now, //if they are, simply issue the memberAdded message keys = (MemberImpl[]) addSuspects.keySet().toArray(new MemberImpl[addSuspects.size()]); for (int i = 0; i < keys.length; i++) { MemberImpl m = (MemberImpl) keys[i]; if ( membership.getMember(m) == null && (memberAlive(m))) { membership.memberAlive(m); super.memberAdded(m); addSuspects.remove(m); if(log.isInfoEnabled()) log.info("Suspect member, confirmed alive.["+m+"]"); } //end if } }
比较乱。。。
启动进程
Daemon Thread [NioReceiver]
Daemon Thread [Tribes-MembershipReceiver]
Daemon Thread [Tribes-MembershipSender]
Daemon Thread [GroupChannel-Heartbeat-1]
总结下:
每间隔500毫秒,讲本身的节点信息进行组播。
节点接受组播信息。
发送和接受后,都调用下面的方法:
protected void checkExpired() { synchronized (expiredMutex) { // timeToExpiration 默认为3秒 MemberImpl[] expired = membership.expire(timeToExpiration); // 不发送组播报的节点就会被认为是故障,并被从cluster删去 for (int i = 0; i < expired.length; i++) { final MemberImpl member = expired[i]; if (log.isDebugEnabled()) log.debug("Mcast exipre member " + expired[i]); try { // 使用一个线程,将故障节点从集群中移除(移除一个节点,需要经过一系列的过程) Thread t = new Thread() { public void run() { service.memberDisappeared(member); } }; t.start(); } catch (Exception x) { log.error("Unable to process member disappeared message.", x); } } } }
获取超过3秒的到期时间。
/** * Runs a refresh cycle and returns a list of members that has expired. * This also removes the members from the membership, in such a way that * getMembers() = getMembers() - expire() * @param maxtime - the max time a member can remain unannounced before it is considered dead. * @return the list of expired members */ public synchronized MemberImpl[] expire(long maxtime) { if(!hasMembers() ) return EMPTY_MEMBERS; ArrayList list = null; Iterator i = map.values().iterator(); while(i.hasNext()) { MbrEntry entry = (MbrEntry)i.next(); if( entry.hasExpired(maxtime) ) { if(list == null) // only need a list when members are expired (smaller gc) list = new java.util.ArrayList(); list.add(entry.getMember()); } } if(list != null) { MemberImpl[] result = new MemberImpl[list.size()]; list.toArray(result); for( int j=0; j<result.length; j++) { removeMember(result[j]); } return result; } else { return EMPTY_MEMBERS ; } }
判断时间是否到期
/** * Check if this dude has expired * @param maxtime The time threshold */ public boolean hasExpired(long maxtime) { long delta = System.currentTimeMillis() - lastHeardFrom; return delta > maxtime; }
下面是session的同步,后台Engine启动的一个线程,不间断的跑下面的job,对session进行同步:
下面是addToQueue方法:
public boolean addToQueue(ChannelMessage msg, Member[] destination, InterceptorPayload payload) { final LinkObject obj = new LinkObject(msg,destination,payload); Runnable r = new Runnable() { public void run() { sendAsyncData(obj); } }; executor.execute(r); return true; }
sendAsyncData(obj),异步发送信息:
NIO发送信息:
private int doLoop(long selectTimeOut, int maxAttempts, boolean waitForAck, ChannelMessage msg) throws IOException, ChannelException { int completed = 0; int selectedKeys = selector.select(selectTimeOut); if (selectedKeys == 0) { return 0; } Iterator it = selector.selectedKeys().iterator(); while (it.hasNext()) { SelectionKey sk = (SelectionKey) it.next(); it.remove(); int readyOps = sk.readyOps(); sk.interestOps(sk.interestOps() & ~readyOps); NioSender sender = (NioSender) sk.attachment(); try { if (sender.process(sk,waitForAck)) { completed++; sender.setComplete(true); if ( Logs.MESSAGES.isTraceEnabled() ) { Logs.MESSAGES.trace("ParallelNioSender - Sent msg:" + new UniqueId(msg.getUniqueId()) + " at " +new java.sql.Timestamp(System.currentTimeMillis())+ " to "+sender.getDestination().getName()); } SenderState.getSenderState(sender.getDestination()).setReady(); }//end if } catch (Exception x) { SenderState state = SenderState.getSenderState(sender.getDestination()); int attempt = sender.getAttempt()+1; boolean retry = (sender.getAttempt() <= maxAttempts && maxAttempts>0); synchronized (state) { //sk.cancel(); if (state.isSuspect()) state.setFailing(); if (state.isReady()) { state.setSuspect(); if ( retry ) log.warn("Member send is failing for:" + sender.getDestination().getName() +" ; Setting to suspect and retrying."); else log.warn("Member send is failing for:" + sender.getDestination().getName() +" ; Setting to suspect.", x); } } if ( !isConnected() ) { log.warn("Not retrying send for:" + sender.getDestination().getName() + "; Sender is disconnected."); ChannelException cx = new ChannelException("Send failed, and sender is disconnected. Not retrying.",x); cx.addFaultyMember(sender.getDestination(),x); throw cx; } byte[] data = sender.getMessage(); if ( retry ) { try { sender.disconnect(); sender.connect(); sender.setAttempt(attempt); sender.setMessage(data); }catch ( Exception ignore){ state.setFailing(); } } else { ChannelException cx = new ChannelException("Send failed, attempt:"+sender.getAttempt()+" max:"+maxAttempts,x); cx.addFaultyMember(sender.getDestination(),x); throw cx; }//end if } } return completed; }
上面是在tomcat启动时,会启动的过程,下面还有个在访问的情况下,session同步,还有个步骤:
至此,tomcat的集群源码大致分析完毕。
发表评论
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tomcat中的线程
2012-02-21 15:14 4210tomcat启动过程中会启动许多线程 这里总结下: ... -
学习HTTP Status Code的一些总结
2012-02-09 11:07 2259这几天学习了一下 ... -
Tomcat的Session管理与后台处理
2012-02-06 21:22 1648转载自: http://zddava.ite ... -
Tomcat的WebappClassLoader(web应用类加载器)详解
2012-02-05 16:44 1992转载自: http://bl ... -
tomcat 源码解析
2011-12-31 15:45 1650tomcat 首先启动 1. 启动的时候对配置文件进行解析。 ... -
tomcat源码安装并调试
2011-12-29 12:35 1909闲来无事,做B/S开发,tomcat天天用,但是对于其原理以及 ... -
eclipse tomcat 配置
2011-09-15 16:10 1944Configure Tomcat's Paths The ... -
META-INF/context.xml文件说明
2011-09-14 11:29 10688crossContext 如果想在应用内调用ServletC ... -
Linux部署tomcat
2011-04-07 09:19 2507今天,同事的服务器上部署一个新的tomcat,但他的服 ...
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