中文（内容有滞后）：http://www.oracle.com/technetwork/cn/middleware/ias/downloads/wls-main-091116-zhs.html

Oracle优秀英文博客：

• WebLogic Server 团队
• James Bayer
• Antony Reynolds
• Adam Bien
• Middleware Magic

• The Aquarium
• Jeff West
• Steve Button
• Markus Eisele

• Arun Gupta
• John Graves
• Bala Kothandaraman
• Simon Haslam

声明:本站WebLogic文章将同步整理到老刘文库.

来源：http://allthingsmdw.blogspot.com/2012/02/multicast-vs-unicast-with-weblogic.html

THURSDAY, FEBRUARY 9, 2012

Multicast Vs. Unicast with WebLogic Clustering

WebLogic Clusters manage membership via messaging within its members. The members join/leave the cluster as well as update other members via messages to the entire cluster. There are two ways for cluster messaging in WLS - Multicast or Unicast. This post goes provides a brief overview of the cluster messaging and some general guidelines around using the different messaging options.
WLS Cluster
WebLogic clustering provides a homogeneous model for managing a set of server instances while providing scalability, load balancing and high availability to the services running within the member instances. For the end client, it appears like one single and uniform service with all the RASP (reliability, availability, scalability, performance) capabilities. Each cluster member is aware of other members and advertise each other services in addition to their own. Refer tohttp://docs.oracle.com/cd/E11035_01/wls100/cluster/failover.html for more details on replication and failover of clustered services.
Unicast & Multicast
Multicast is easier to explain over Unicast. Multicast is a broadcast UDP option for sending a packet/announcement over to a group that is listening on a specific multicast address and port over which the announcement is sent.There is a defined range for valid Multicast address (224.0.0.1 to 239.255.255.255). Everyone listening on the given address hears the announcement just like following a Twitter post. Some limitations with Multicast is the TTL (time to live) across machines/subnets/routers needs to be adjusted and the routers configured to retransmit the multicast packet across subnets. More details on the weblogic specific multicast configurations can be seen in my Exalogic and Multicast blog post.
Unicast is more of a point to point UDP option to send the packet to a specific member and not everyone. That way, unicast is more of a private conversation between two individuals while multicast is more of a shout to a group or room. Both are UDP based, so there can be losses unlike TCP that handles retransmissions on message loss. But Unicast can span across routers and does not have to worry about TTL without the everyone hearing the announcement. So, Network Admins in general prefer to go with Unicast over Multicast for these reasons.
WLS Cluster Configuration
When a cluster is created within a WLS Domain (either via wlst or config wizard or copy/update of existing domain), it is configured as using Unicast or Multicast messaging. As part of complete Cluster configuration, the multicast listen address and port should be specified if going with Multicast option. Also the managed servers should be targeted/added to the Cluster instance. There can be multiple clusters and any given managed server instance can only belong to atmost one cluster (or none). This will let the clustered managed servers (Admin Server should not be part of any cluster nor can cluster span domains) go with Unicast or Multicast when they are started. It should be noted that Multicast used to be the only option in WebLogic prior to 10.0 version while either Unicast or Multicast can be used from version 10 onwards.
Cluster Messaging
How does each member join the cluster and see or recognize others? At bootstrap time, the managed servers get their configuration via JMX MBeans from the Admin server (or from cached configurations if the Admin server was down) and recognize that they belong to a cluster and they have to go with Unicast or Multicast.
WLS Multicast Messaging
So, in a multicast messaging cluster, the managed servers start listening to the specified multicast address once it checks its configuration and knows it belongs to so and so cluster and has to use specified multicast address and port. Once it listens on the specified multicast address, it sends an announcement about its arrival to others via multicast - more like a shout-out. Other running clustered members of the same cluster who are already listening will respond back and add the new member to their list of known cluster members. The new member will also update its cluster list with other members. This process continues as new members get added. The membership gets renewed based on each member sending periodic announcements to other members proclaiming its liveliness. If a member goes down (shutdown or killed or not able to respond), then it wont be able to send its broadcasts and other members will drop it from the cluster list and re-add it when it comes back online. If a member is directly talking to another cluster member, just the direct socket connection is enough in establishing its membership with its connected member. Since multicast is a broadcast, just a single announcement is retain a instance's membership and let others continue to maintain it in their cluster list till its time to renew its membership. Its a mesh where every member can see every other member in the cluster.

WLS Unicast Messaging
With Unicast, WLS divides the cluster into a multiple groups, each having a max of 10 members. The division happens as the servers come up. Each of the server listens on their specified listen address and the other members can send/receive unicast packets over that listen address as every clustered member knows the configurations of other cluster members.
The oldest within the group is designated the group leader. The group leader communicates over Unicast to other members (over the specified member's listen address) within its group and adds/drops them based on them renewing their membership or not responding. The group leaders communicate amongst themselves. So, if there are 4 group leaders, each group having 10 servers, a membership announcement from server1 in group1 will be picked by GroupLeader1 of group1 and retransmitted to all other members within the group1 as well as to other three group leaders. The remaining group leaders will in-turn retransmit the membership information within their groups. This way, every change is picked up and retransmitted by the group leaders to within their group and to other groups via group leader to group leader communication. The group leaders remain the hub for each group while they themselves form a mesh with other group leaders.

Comparison between Unicast & Multicast

Multicast	Unicast
Only option in pre-10.0 versions of WLS, continues to exist in version 10+	Available from version 10 onwards
Requires configurations to Routers, TTL	No configuration required
Requires configuring the Multicast Listen Address and port	Just specify the listen address (can be Default Channel or use a Custom Network Channel for Cluster communication)
One announcement to join/maintain membership	one transmission to group leader has to be retransmitted to other group members (N) + to other group leaders (M) who then again retransmit to their group members resulting in (NxM) packets
Everyone sees everyone	Group Leaders have to do real heavy lifting of retransmitting every thing across its group and other group leaders and can get bogged down in just retransmitting
Can lead to big broadcasts through the entire subnet/LAN if there are frequent joins/drops of members or change in services (JNDI updates of bound services, frequent app deployments or members going out of sync)	Not a broadcast throughout the subnet/lan, but still more packets to be sent across as Group Leaders have to retransmit everything. Can consume bigger bandwidth

As listed in the table above, these would be my guidelines:

1. If the cluster is small and simple (under 20 members), go with Unicast. No configurations required and the group leaders wont be stretched retransmitting data.

2. If the Network configurations strictly prohibit multicast and members have to reside in different subnets and cluster sizes are still under or mid-20s, go with Unicast.

3. If its a real large cluster (over 20 members) and members can reside in the same subnet or even if they are not on same subnet but network router configurations can allow multicast, go with Multicast.

4. If over 50 members, change to network configurations to allow multicast and stick with Multicast.

5. Over 100 members, try to break up the domain into multiple separate domains and individual clusters for better administration and management even though Multicast option can handle such large domains. Or use custom scripts/wlst to manage and monitor individual members instead of relying on a single application (like console) to manage/monitor/handle all servers at the domain level.

The reason for recommending Multicast over Unicast for large clusters is due to the work load on the group leaders and retransmissions. The group leaders have to retransmit every member's packet within their group as well as to other group leaders (who again send to their group members) which can just lead to more and more work as the cluster grows bigger.
Another big reason is that WLS Multicast based messaging is quite mature and stable compared to Unicast which got only introduced with version 10. Also, with unicast, there can still be retransmits (as its not auto error correcting) and it can consume more bandwidth due to repeat retransmits by group leaders to others compared to one transmit for multicast.
Conclusions
I hope this article helps clarify the internal working of WLS Cluster membership around Unicast vs Multicast messaging while providing some guidance on the option to use based on requirements and constraints.

Posted by Sabha Parameswaran at 12:33 PM

文档:http://www.oracle.com/technetwork/middleware/weblogic/documentation/index.html

此次同时发布的还有Oracle Fusion Middleware 11g R1 (11.1.1.6.x),包含下列产品:

• Oracle WebLogic Server 11g R1 (10.3.6)
• Oracle SOA Suite 11g R1 (11.1.1.6.0)
• Oracle Business Process Management 11g R1 (11.1.1.6.0)
• Oracle Complex Event Processing 11g R1 (11.1.1.6.0)
• Oracle Service Bus 11g R1 (11.1.1.6.0)
• Oracle Enterprise Repository 11g R1 (11.1.1.6.0)
• Oracle Service Registry 11g R1 (11.1.1.6)
• Oracle Application Integration Architecture Foundation Pack 11g R1 (11.1.1.6.0)
• Oracle Data Integrator 11g R1 (11.1.1.6.0)
• Oracle WebCenter Portal 11g R1 (11.1.1.6.0)
  (previously known as Oracle WebCenter Suite)
• Oracle WebCenter Content 11g R1 (11.1.1.6.0)
  (previously known as Oracle Enterprise Content Management)
• Oracle Identity Management 11g R1 (11.1.1.6.0)
• Oracle Forms, Reports, Portal & Discoverer 11g R1 (11.1.1.6.0)
• Oracle Traffic Director 11g R1 (11.1.1.6)
• Oracle Repository Creation Utility 11g R1 (11.1.1.6.0)
• Oracle JDeveloper & Application Development Framework 11g R1 (11.1.1.6.0)

一共约137篇文章，已经上传完毕，除个别文件因命名问题外上传失败，95%的文章已经可以直接浏览或打包下载了。WebLogic中文博客目前正在致力于新版本的通用Java中间件监控软件的研发中（单一软件支持Tomcat, Resin, JBoss, WebLogic, WebSphere，JVM运行状态监控等），因此近期将不会发表新的技术文章。如果您需要这些文章的word版本，请联系本人购买：beansoft@126.com 或者 QQ 9991483。

下面是所有WebLogic文章索引：

2009-11-01 配置 WebLogic Server 11g 集群单服务器版（Windows）.pdf
2009-11-06 WebLogic Server 11g节点管理器和Machine配置单机版（Windows）.pdf
2009-11-06 关于Spring和WebLogic版本兼容的一点小提示.pdf
2009-11-09 WebLogic 11g 如何修改 Console 的端口.pdf
2009-12 Weblogic 11 集群和节点管理器配置快速入门视频(单服务器版).pdf
2010-01-25 WebLogic各个版本对JDK和Spring的支持度.pdf
2010-03-23 JNDI 访问外部 WebLogic 11 数据源的操作步骤.pdf
2010-05-07 Oracle WebLogic Server 11g Rel 1 (10.3.3) 发布.pdf
2010-07-15 WLST on Weblogic 8.1下载地址(转).pdf
2010-08 WebLogic 9.2.4.0 发布.pdf
2010-08-13 WebLogic 11g 下载地址及 OEPE所有版本官方下载地址及所有版本文档(edoc)阅读下载地址.pdf
2010-08-16久违或遗忘的WebLogic Java工具.pdf
2010-08-19 简单的HelloWorld Portal 应用(for WLS 10).pdf
2010-08-20韩国wls监控 WLMonitor 2.5 beta 1 英文版下载.pdf
2010-08-31 Where to download file wlfullclient.jar.pdf
2010-09-09 WebLogic和JDK版本稳定度排行榜.pdf
2010-09-10 WebLogic静默卸载与安装[Slient Install and Uninstall].pdf
2010-11-26 WebLogic集群实现HTTP复制的简单步骤.pdf
2010-12-09 WebLogic Edoc中关于weblogic.Deployer的一点小问题.pdf
2011-02-27 如何修改weblogic默认线程池大小.pdf
2011-02-28 如何破解WebLogic管理密码.pdf
2011-03 WebLogic如何使用GridLink连接RAC数据库.pdf
2011-04-18 WebLogic散包部署禁用热加载.pdf
2011-05-07 WebLogic 10.3.5正式发布,提供下载.pdf
2011-05-22 基于JMS的Weblogic Server Webservice开发.pdf
2011-05-22基于JMS的Weblogic Server Webservice开发.pdf
2011-07-03 WebLogic 10.3.4支持JDK 7.pdf
2011-07-26借助 SAML 实现 WebLogic Server 9.2 单点登录相关文章.pdf
2011-07-28同时使用Oracle Exalogic Elastic Cloud和Exadata Database Machine的SquareTwo Financial公司[转].pdf
2011-07-31 3D立体展示 Oracle Exalogic Elastic Cloud X2-2.pdf
2011-08-03 关于WebLogic Windows 7版本.pdf
2011-08-04 ExaLogic EL X2-2 Edoc在线阅读及下载地址,安装视频.pdf
2011-08-12 WebLogic如何处理socket muxers[转].pdf
2011-08-23 Weblogic 10.3.5在64位Windows系统下的安装和配置.pdf
2011-08-24 WebLogic中的监视仪表盘(图文,视频).pdf
2011-08-26 WEBLOGIC JMS 点对点配置详解.pdf
2011-08-29使用WLST创建和删除DataSource.pdf
2011-08-30 WebLogic Express是免费的嘛 WebLogic是免费的嘛.pdf
2011-08-30 WLST快速创建单机Domain.pdf
2011-08-31 Solaris下如何安装WebLogic.pdf
2011-09-02使用代理插件时群集中的 HTTP 负载平衡问题[转].pdf
2011-09-04 AIX下WebLogic安装操作手册[转].pdf
2011-09-10调试基本WebLogic JDBC问题[转].pdf
2011-09-29 优化WebLogic 8服务器性能参数[转].pdf
2011-10 WebLogic Server Blog 内容收藏.pdf
2011-10-07 DomainHealth 1.0.0 发布.pdf
2011-10-10 使用WLST配置WebLogic密码策略.pdf
2011-10-19 WebLogic NodeManager 远程攻击漏洞补丁下载.pdf
2011-11 GlassFish 4.0 视频曝光,控制台酷似WebLogic.pdf
2011-11-09 WebLogic Web 应用映射到根目录.pdf
2011-11-28 如何抓取Thread Dump小结.pdf
2011-12 Oracle WebLogic Server 12c (12.1.1)正式发布.pdf
2011-12 WebLogic所有版本Edoc在线阅读及下载地址.pdf
2011-12 转载－weblogic 类加载机制.pdf
2011-12-02 Weblogic - Socket Muxers in Thread Dumps[转].pdf
2012-01-29各个版本WebLogic所支持的JDK及JavaEE版本.pdf
Accessing JMX for Oracle WebLogic 11g.pdf
BEA Weblogic Server宝典[中文图片版] [PDF].pdf
BEA Weblogic、Tuxedo 下载地址[转].pdf
BEA 产品文档[转].pdf
BEA-000337 错误解决[转].pdf
BEA-000402问题解决 but the maximum number of socket reader threads allowed by the configuration is.pdf
BEA公司被收购前所有版本软件支持的操作系统等配置信息列表.pdf
chaowang在甲骨文社区日的演讲教材下载.pdf
Debugging WebLogic Platform Internals.pdf
Enable IIOP and default user for the WebLogic server[转].pdf
Installing Oracle WebLogic Server and Creating a Domain [Linux].pdf
Jython相关文章收藏.pdf
Linux下Weblogic 11g jar格式安装包如何安装.pdf
Managing WebLogic servers with JConsole.pdf
Monitoring WebLogic 9 using JMX.pdf
Oracle Fusion Middleware支持的JDK等系统配置列表信息.pdf
Oracle WebLogic Integration.pdf
Oracle WebLogic Server 11g Monitor and Tune Performance课程介绍[转].pdf
Oracle WebLogic Server Enterprise Edition 报价.pdf
Oracle WebLogic Server Information Center[转].pdf
Oracle官方关于WebLogic服务有效期的文档.pdf
Performance and Tuning for Oracle WebLogic Server 11g[PDF] Download.pdf
Reason of java.lang.InternalError： erroneous handlers.pdf
startWebLogic.sh启动失败，提示Error initializing Embedded LDAP Server错误.pdf
WebLogic 10.3.4正式发布,提供下载,支持JSF 2.0, JPA 2.0和JAX-RS 1.1[图].pdf
WebLogic 10各个版本详细名称.pdf
Weblogic 11g 安装部署手册.pdf
WebLogic 11gR1 PS3所有BEA错误代码详细信息列表.pdf
WebLogic 8 debug flags.pdf
WebLogic 8 监控 wlstat 0.2, 方便监控weblogic的Sockets,jvm,jdbc,threads,session.pdf
WebLogic 8.1 FTP 下载地址(Windows版本).pdf
WebLogic 8.1.6 Windows 安装包下载.pdf
WebLogic 8.1.6的所有BEA错误代码索引.pdf
WebLogic 9 实现基于Oracle数据库的用户身份存储示例代码.pdf
Weblogic 9.2 部署 8.1 下运行的 EAR 出错的部分解决方法.pdf
WebLogic 9.2的所有BEA错误代码索引.pdf
Weblogic for aix操作手册.pdf
WebLogic JDBC 驱动的配置.pdf
WebLogic JSP Servlet 线程超时设置参数.pdf
WebLogic Portal服务器配置手册.pdf
WebLogic Server 10.3.4 Released – Key APIs of Java EE 6 and More[转].pdf
WebLogic Server 9 的 Web Service 编程之 JWS.pdf
WebLogic Server 9.2 集群配置单服务器版.pdf
WebLogic Server 9.2 集群配置单服务器版和多服务器版(PDF).pdf
WebLogic Server 9.2 集群配置多服务器版.pdf
WebLogic versioned deployment side-by-side[转].pdf
WebLogic 最新版本下载地址.pdf
weblogic.Admin[转].pdf
weblogic.security.internal.encryption.EncryptionServiceException： com.rsa.jsafe.JSAFE_PaddingException： Could not perform unpadding： invalid pad byte.pdf
weblogic.utils.classloaders.FilteringClassLoader所在包.pdf
WebLogic8.1打印详细的jdbc日志.pdf
Weblogic8.1集群中批量启动和关闭所有服务器的脚本[转].pdf
weblogic9 jdbc日志跟weblogic8的区别.pdf
WebLogic公司发展简史.pdf
WebLogic启用域之间的跨域安全 Enable Cross Domain Security between domains[转].pdf
WebLogic如何强制先加载WEB-INF／lib下的jar.pdf
WebLogic如何更换64位JDK[转].pdf
WebLogic密码恢复（一）[转].pdf
WebLogic密码恢复（二）[转].pdf
Weblogic的Machine,Server,Domain,Cluster的关系.pdf
WebLogic集群环境下如何访问EJB实现负载均衡.pdf
WLS10.3.0中，连接测试导致的connection pool shrinking(disabling)问题分析[转].pdf
WLST脚本获取ThreadDump[转].pdf
[WebLogic]dev2dev 2004 合订本下载.pdf
[转]EJB在Weblogic Server集群中的实现.pdf
[转]WebLogic 10.3.4 新功能：CAT - Classloader分析工具.pdf
[转]WebLogic ClassCastException 错误解析.pdf
[转]将WebLogic Server注册为Windows服务.pdf
【转】Weblogic挂起、宕机问题分析及优化.pdf
使用VisualVM远程监控WebLogic服务器JVM.pdf
使用WLST监控应用状态[转].pdf
使用WLST脚本列出JMS队列中的消息.pdf
删除WebLogic 10的缓存[转].pdf
原dev2dev的WebLogic General精华贴总.pdf
如何抓取Thread Dump小结.pdf
开发自定义的MBean来管理J2EE应用(第四部分)[转].pdf
想在WLST中运行本机命令.pdf
监控线程执行情况,耗光时自动输出thread内容[转].pdf
简单的Oracle WebLogic 11g安装部属手册(PDF).pdf
转 多机nodemanager测试小记&weblogic103.pdf
配置基于Coherence 的WebLogic Server会话管理[转].pdf
Weblogic 8.1 JNDI 教程PPT.swf
WebLogic Server 8.1 Performance Tuning Guide(调优中文文档).swf
对WebLogic Server JNDI 启用安全设置.swf
设置WebLogic集群(WebLogic 10 中文文档).swf

作者: 刘长炯 BeanSoft@126.com 日期: 2011-11-28 本文环境: JDK 1.5/1.6, WebLogic 9.0 or later

当服务器挂起,崩溃或者性能底下时,就需要抓取服务器的线程堆栈(Thread Dump)用于后续的分析.

Thread dump提供了当前活动的线程的快照. 它提供了JVM中所有Java线程的栈跟踪信息

有很多方式可用于获取Thread Dump, 一些是操作系统特定的命令.

操作系统命令获取ThreadDump:

Windows:

1.      转向服务器的标准输出窗口并按下Control + Break组合键, 之后需要将线程堆栈复制到文件中

UNIX/ Linux

首先查找到服务器的进程号(process id), 然后获取堆栈.

1.      ps –ef  | grep java

2.      kill -3 <pid>

 注意一定要谨慎, 一步不慎就可能让服务器进程被杀死!

JVM 自带的工具获取线程堆栈:

JDK自带命令行工具获取PID并做ThreadDump:

1.         jps

2.         jstack <pid>

使用JVisualVM:

Threads 标签页àThreadDump按钮.

WebLogic 自带的获取 thread dump的工具:

1. webLogic.Admin 工具

a. 打开命令提示符, 通过运行<DOMAIN_HOME>/bin/setDomain.env设置相关类路径

b. 执行下面的命令

java weblogic.Admin -url t3://localhost:7001 -username weblogic -password weblogic1 THREAD_DUMP

注意: Thread Dump 会打印到标准输出, 如nohup日志或者进程窗口.

2. 使用 Admin Console

a. 登录 Admin Console , 点击对应的服务器

b. 点击Server à Monitoring àThreads

c. 点击: Dump Thread Stack 按钮

3. 使用WLST (WebLogic Scripting Tool)

connect(‘weblogic’,'weblogic1’,’t3://localhost:7001’)

cd(‘Servers’)

cd(‘AdminServer’)

threadDump()

disconnect()

exit()

注意: 线程堆栈将会保存在运行wlst的当前目录下.

4. 使用utils.ThreadDumper

用法:

C:\bea\wlserver_10.3\server\lib>java -cp weblogic.jar utils.ThreadDumper

Broadcast Thread dumps disabled: must specify weblogic.debug.dumpThreadAddr and

weblogic.debug.dumpThreadPort

Exception in thread "main" java.lang.IllegalArgumentException: Port out of range

:-1

        at java.net.DatagramPacket.setPort(Unknown Source)

        at java.net.DatagramPacket.<init>(Unknown Source)

        at java.net.DatagramPacket.<init>(Unknown Source)

        at utils.ThreadDumper.sendDumpMsg(ThreadDumper.java:124)

        at utils.ThreadDumper.main(ThreadDumper.java:145)

5. 如果服务器是作为Windows服务的方式运行, 请运行下列命令:

WL_HOME\bin\beasvc -dump -svcname:service-name

其它一些获取Thread Dump的工具有jrcmd, jrmc(JRockit VM自带) ,Samurai, JProfiler等, 还可通过JMX编程的方式获取, 如JDK自带示例代码:

$JAVA_HOME\demo\management\FullThreadDump