Tomcat  jsvc 调优及JMX监控

实验背景

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系统版本：CentOS release 6.5 (Final)

Tomcat版本:   Apache-tomcat-7.0.54

Tomcat介绍：

Tomcat是Apache 软件基金会（Apache Software Foundation）的Jakarta 项目中的一个核心项目，由Apache、Sun 和其他一些公司及个人共同开发而成。由于有了Sun 的参与和支持，最新的Servlet 和JSP 规范总是能在Tomcat 中得到体现，Tomcat 5支持最新的Servlet 2.4 和JSP 2.0 规范。因为Tomcat 技术先进、性能稳定，而且免费，因而深受Java 爱好者的喜爱并得到了部分软件开发商的认可，成为目前比较流行的Web 应用服务器。目前最新版本是8.0。

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Tomcat 7最新版本下载链接：
http://mirrors.cnnic.cn/apache/tomcat/tomcat-7/v7.0.56/bin/apache-tomcat-7.0.56.tar.gz

Tomcat 安装：
tar zxvf apache-tomcat-7.0.54.tar.gz -C /opt/

jsvc编译及调优：
cd  apache-tomcat-7.0.54/bin
tar zxvf commons-daemon-native.tar.gz
cd commons-daemon-1.0.x-native-src/unix
./configure
make -j4
cp jsvc ../../
cd ../../

添加tomcat用户，后面用来启动tomcat进程：
useradd -s /sbin/nologin tomcat

jsvc help文件:
# export JAVA_HOME=/opt/jdk1.7.0_60/
# ./jsvc --help
Usage: jsvc [-options] class [args...]
Where options include:-help | --help | -?show this help page (implies -nodetach)-jvm <JVM name>use a specific Java Virtual Machine. Available JVMs:'server'-clientuse a client Java Virtual Machine.-serveruse a server Java Virtual Machine.-cp | -classpath <directories and zip/jar files>set search path for service classes and resouces-java-home | -home <directory>set the path of your JDK or JRE installation (or setthe JAVA_HOME environment variable)-versionshow the current Java environment version (to checkcorrectness of -home and -jvm. Implies -nodetach)-showversionshow the current Java environment version (to checkcorrectness of -home and -jvm) and continue execution.-nodetachdon't detach from parent process and become a daemon-debugverbosely print debugging information-checkonly check service (implies -nodetach)-user <user>user used to run the daemon (defaults to current user)-verbose[:class|gc|jni]enable verbose output-cwd </full/path>set working directory to given location (defaults to /)-outfile </full/path/to/file>Location for output from stdout (defaults to /dev/null)Use the value '&2' to simulate '1>&2'-errfile </full/path/to/file>Location for output from stderr (defaults to /dev/null)Use the value '&1' to simulate '2>&1'-pidfile </full/path/to/file>Location for output from the file containing the pid of jsvc(defaults to /var/run/jsvc.pid)-D<name>=<value>set a Java system property-X<option>set Virtual Machine specific option-ea[:<packagename>...|:<classname>]-enableassertions[:<packagename>...|:<classname>]enable assertions-da[:<packagename>...|:<classname>]-disableassertions[:<packagename>...|:<classname>]disable assertions-esa | -enablesystemassertionsenable system assertions-dsa | -disablesystemassertionsdisable system assertions-agentlib:<libname>[=<options>]load native agent library <libname>, e.g. -agentlib:hprof-agentpath:<pathname>[=<options>]load native agent library by full pathname-javaagent:<jarpath>[=<options>]load Java programming language agent, see java.lang.instrument-procname <procname>use the specified process name-wait <waittime>wait waittime seconds for the service to startwaittime should multiple of 10 (min=10)-stopstop the service using the file given in the -pidfile option-keepstdindoes not redirect stdin to /dev/null
jsvc (Apache Commons Daemon) 1.0.15-dev
Copyright (c) 1999-2013 Apache Software Foundation.

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接下来是重点了！

复制bin目录下的daemon.sh 生成初步service文件# cp ./daemon.sh /etc/init.d/tomcat
# chmod +x /etc/init.d/tomcat

jsvc 调优参数：
export PATH=/bin:/sbin:/usr/bin:/usr/sbin
export JAVA_HOME=/opt/jdk1.7.0_60
export JRE_HOME=/opt/jdk1.7.0_60/jre
export CATALINA_BASE=/opt/apache-tomcat-7.0.54
export CATALINA_HOME=/opt/apache-tomcat-7.0.54
export CATALINA_PID=$CATALINA_BASE/logs/catalina-daemon.pid
export CATALINA_TMP=$CATALINA_BASE/temp
export TOMCAT_USER=tomcat
export CATALINA_OPTS="-server -Xss512k -Xms2048M -Xmx2048M -XX:MaxPermSize=256M -XX:PermSize=128M -XX:NewSize=128M -XX:+CMSIncreme
ntalMode -XX:CMSInitiatingOccupancyFraction=80 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:ParallelGCThreads=8 -Djavax.servlet.r
equest.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Dfile.encoding=UTF-8 -Duser.timezone=Asia/Shanghai -Dcom.sun.manage
ment.jmxremote -Dcom.sun.management.jmxremote.port=100861 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.a
uthenticate=false -Djava.rmi.server.hostname=192.168.3.5"

-XX:+CMSIncrementalMode
该标志将开启CMS收集器的增量模式。增量模式经常暂停CMS过程，以便对应用程序线程作出完全的让步。因此，收集器将花更长的时间完成整个收集周期。因此，只有通过测试后发现正常CMS周期对应用程序线程干扰太大时，才应该使用增量模式。由于现代服务器有足够的处理器来适应并发的垃圾收集，所以这种情况发生得很少。

-XX:CMSInitiatingOccupancyFraction
当堆满之后，并行收集器便开始进行垃圾收集，例如，当没有足够的空间来容纳新分配或提升的对象。对于CMS收集器，长时间等待是不可取的，因为在并发垃圾收集期间应用持续在运行(并且分配对象)。因此，为了在应用程序使用完内存之前完成垃圾收集周期，CMS收集器要比并行收集器更先启动。
因为不同的应用会有不同对象分配模式，JVM会收集实际的对象分配(和释放)的运行时数据，并且分析这些数据，来决定什么时候启动一次CMS垃圾收集周期。为了引导这一过程， JVM会在一开始执行CMS周期前作一些线索查找。该线索由 -XX:CMSInitiatingOccupancyFraction=<value>来设置，该值代表老年代堆空间的使用率。比如，value=75意味着第一次CMS垃圾收集会在老年代被占用75%时被触发。通常CMSInitiatingOccupancyFraction的默认值为68(之前很长时间的经历来决定的)。

-XX：+UseConcMarkSweepGC
该标志首先是激活CMS收集器。默认HotSpot JVM使用的是并行收集器。

-XX：UseParNewGC
当使用CMS收集器时，该标志激活年轻代使用多线程并行执行垃圾回收。这令人很惊讶，我们不能简单在并行收集器中重用-XX：UserParNewGC标志，因为概念上年轻代用的算法是一样的。然而，对于CMS收集器，年轻代GC算法和老年代GC算法是不同的，因此年轻代GC有两种不同的实现，并且是两个不同的标志。
注意最新的JVM版本，当使用-XX：+UseConcMarkSweepGC时，-XX：UseParNewGC会自动开启。因此，如果年轻代的并行GC不想开启，可以通过设置-XX：-UseParNewGC来关掉。

XX：ConcGCThreads
标志-XX：ConcGCThreads=<value>(早期JVM版本也叫-XX:ParallelCMSThreads)定义并发CMS过程运行时的线程数。比如value=4意味着CMS周期的所有阶段都以4个线程来执行。尽管更多的线程会加快并发CMS过程，但其也会带来额外的同步开销。因此，对于特定的应用程序，应该通过测试来判断增加CMS线程数是否真的能够带来性能的提升。
如果还标志未设置，JVM会根据并行收集器中的-XX：ParallelGCThreads参数的值来计算出默认的并行CMS线程数。该公式是ConcGCThreads = (ParallelGCThreads + 3)/4。因此，对于CMS收集器， -XX:ParallelGCThreads标志不仅影响“stop-the-world”垃圾收集阶段，还影响并发阶段。
总之，有不少方法可以配置CMS收集器的多线程执行。正是由于这个原因,建议第一次运行CMS收集器时使用其默认设置, 然后如果需要调优再进行测试。只有在生产系统中测量(或类生产测试系统)发现应用程序的暂停时间的目标没有达到 , 就可以通过这些标志应该进行GC调优。

-XX:ParallelGCThreads=n:设置并行收集器收集时使用的CPU数。并行收集线程数。

接下来这些参数 是针对于 JMX 远程监控的：
-Dcom.sun.management.jmxremote 启用JMX远程监控
-Dcom.sun.management.jmxremote.port=100861 使用端口100861
-Dcom.sun.management.jmxremote.authenticate=false 远程连接不需要密码认证
-Dcom.sun.management.jmxremote.ssl=false 不使用SSL
-Dcom.sun.management.jmxremote.access.file=$CATALINA_HOME/conf/jmxremote.access 使用指定的JMX帐号授权文件
-Dcom.sun.management.jmxremote.password.file=$CATALINA_HOME/conf/jmxremote.password 使用指定的JMX帐号文件

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到这里为止 tomcat 针对jsvc 调优已经差不多了，下面启动tomcat 测试：

# /etc/init.d/tomcat start

# ps -ef |grep tomcat
root     12166     1  0 16:09 ?        00:00:00 jsvc.exec -java-home /opt/jdk1.7.0_60 -user tomcat -pidfile /opt/apache-tomcat-7.0.54/logs/catalina-daemon.pid -wait 10 -outfile /opt/apache-tomcat-7.0.54/logs/catalina-daemon.out -errfile &1 -classpath /opt/apache-tomcat-7.0.54/bin/bootstrap.jar:/opt/apache-tomcat-7.0.54/bin/commons-daemon.jar:/opt/apache-tomcat-7.0.54/bin/tomcat-juli.jar -Djava.util.logging.config.file=/opt/apache-tomcat-7.0.54/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -server -Xss512k -Xms2048M -Xmx2048M -XX:MaxPermSize=256M -XX:PermSize=128M -XX:NewSize=128M -XX:+CMSIncrementalMode -XX:CMSInitiatingOccupancyFraction=80 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:ParallelGCThreads=8 -Djavax.servlet.request.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Dfile.encoding=UTF-8 -Duser.timezone=Asia/Shanghai -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=10086 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.rmi.server.hostname=192.168.3.5 -Djava.endorsed.dirs= -Dcatalina.base=/opt/apache-tomcat-7.0.54 -Dcatalina.home=/opt/apache-tomcat-7.0.54 -Djava.io.tmpdir=/opt/apache-tomcat-7.0.54/temp org.apache.catalina.startup.Bootstrap
tomcat   12167 12166 34 16:09 ?        00:00:05 jsvc.exec -java-home /opt/jdk1.7.0_60 -user tomcat -pidfile /opt/apache-tomcat-7.0.54/logs/catalina-daemon.pid -wait 10 -outfile /opt/apache-tomcat-7.0.54/logs/catalina-daemon.out -errfile &1 -classpath /opt/apache-tomcat-7.0.54/bin/bootstrap.jar:/opt/apache-tomcat-7.0.54/bin/commons-daemon.jar:/opt/apache-tomcat-7.0.54/bin/tomcat-juli.jar -Djava.util.logging.config.file=/opt/apache-tomcat-7.0.54/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -server -Xss512k -Xms2048M -Xmx2048M -XX:MaxPermSize=256M -XX:PermSize=128M -XX:NewSize=128M -XX:+CMSIncrementalMode -XX:CMSInitiatingOccupancyFraction=80 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:ParallelGCThreads=8 -Djavax.servlet.request.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Dfile.encoding=UTF-8 -Duser.timezone=Asia/Shanghai -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=10086 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.rmi.server.hostname=192.168.3.5 -Djava.endorsed.dirs= -Dcatalina.base=/opt/apache-tomcat-7.0.54 -Dcatalina.home=/opt/apache-tomcat-7.0.54 -Djava.io.tmpdir=/opt/apache-tomcat-7.0.54/temp org.apache.catalina.startup.Bootstrap

如果你的系统开起了iptables的话，这里需要开放针对jmx 和 tomcat 的端口：
vim /etc/sysconfig/iptables
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8080 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 10086 -j ACCEPT/etc/init.d/iptables restart
重启防火墙生效；

接下来打开浏览器测试tomcat是否已经work；
http://192.168.3.5:8080

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这里我们验证一下JMX远程监控，推荐使用VisualVM监控；

JDK中还藏着一个宝贝，它的名字叫做VisualVM。VisualVM是Sun的一个OpenJDK项目，其目的在于为Java应用创建一个整套的问题解决工具；

官网主页：
http://visualvm.java.net/

步骤如下：

1）添加远程主机：

2）添加jmx连接:

这里需要注意格式：主机+端口 ，另外下面勾选 不要求SSL连接；

3）添加完成之后打开查看tomcat 资源使用情况；

添加成功之后下面有个jmx的主机连接：

打开即可！

So Next ，Enjoy it！

下面是一个优化后的tomcat启动脚本的范例，可以放置在/etc/init.d/下 使用, start 、 stop等进行启动 、关闭操作；

#!/bin/sh
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# -----------------------------------------------------------------------------
# Scripts for tomcat based on jsvc
# -----------------------------------------------------------------------------
#
# resolve links - $0 may be a softlink
export PATH=/bin:/sbin:/usr/bin:/usr/sbin
export JAVA_HOME=/opt/jdk1.7.0_60
export JRE_HOME=/opt/jdk1.7.0_60/jre
export CATALINA_BASE=/opt/apache-tomcat-7.0.54
export CATALINA_HOME=/opt/apache-tomcat-7.0.54
export CATALINA_PID=$CATALINA_BASE/logs/catalina-daemon.pid
export CATALINA_TMP=$CATALINA_BASE/temp
export TOMCAT_USER=tomcat
export CATALINA_OPTS="-server -Xss512k -Xms2048M -Xmx2048M -XX:MaxPermSize=256M -XX:PermSize=128M -XX:NewSize=128M -XX:+CMSIncrementalMode -XX:CMSInitiatingOccupancyFraction=80 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:ParallelGCThreads=8 -Djavax.servlet.request.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Dfile.encoding=UTF-8 -Duser.timezone=Asia/Shanghai -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=22222 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.rmi.server.hostname=192.168.3.5"
ARG0="$0"
while [ -h "$ARG0" ]; dols=`ls -ld "$ARG0"`link=`expr "$ls" : '.*-> \(.*\)$'`if expr "$link" : '/.*' > /dev/null; thenARG0="$link"elseARG0="`dirname $ARG0`/$link"fi
done
DIRNAME="`dirname $ARG0`"
PROGRAM="`basename $ARG0`"
while [ ".$1" != . ]
docase "$1" in--java-home )JAVA_HOME="$2"shift; shift;continue;;--catalina-home )CATALINA_HOME="$2"shift; shift;continue;;--catalina-base )CATALINA_BASE="$2"shift; shift;continue;;--catalina-pid )CATALINA_PID="$2"shift; shift;continue;;--tomcat-user )TOMCAT_USER="$2"shift; shift;continue;;* )break;;esac
done
# OS specific support (must be 'true' or 'false').
cygwin=false;
darwin=false;
case "`uname`" inCYGWIN*)cygwin=true;;Darwin*)darwin=true;;
esac
# Use the maximum available, or set MAX_FD != -1 to use that
test ".$MAX_FD" = . && MAX_FD="maximum"
# Setup parameters for running the jsvc
#
test ".$TOMCAT_USER" = . && TOMCAT_USER=tomcat
# Set JAVA_HOME to working JDK or JRE
# JAVA_HOME=/opt/jdk-1.6.0.22
# If not set we'll try to guess the JAVA_HOME
# from java binary if on the PATH
#
if [ -z "$JAVA_HOME" ]; thenJAVA_BIN="`which java 2>/dev/null || type java 2>&1`"test -x "$JAVA_BIN" && JAVA_HOME="`dirname $JAVA_BIN`"test ".$JAVA_HOME" != . && JAVA_HOME=`cd "$JAVA_HOME/.." >/dev/null; pwd`
elseJAVA_BIN="$JAVA_HOME/bin/java"
fi
# Only set CATALINA_HOME if not already set
test ".$CATALINA_HOME" = . && CATALINA_HOME=`cd "$DIRNAME/.." >/dev/null; pwd`
test ".$CATALINA_BASE" = . && CATALINA_BASE="$CATALINA_HOME"
test ".$CATALINA_MAIN" = . && CATALINA_MAIN=org.apache.catalina.startup.Bootstrap
# If not explicitly set, look for jsvc in CATALINA_BASE first then CATALINA_HOME
if [ -z $JSVC ]; thenJSVC="$CATALINA_BASE/bin/jsvc"if [ ! -x $JSVC ]; thenJSVC="$CATALINA_HOME/bin/jsvc"fi
fi
# Set the default service-start wait time if necessary
test ".$SERVICE_START_WAIT_TIME" = . && SERVICE_START_WAIT_TIME=10
# Ensure that any user defined CLASSPATH variables are not used on startup,
# but allow them to be specified in setenv.sh, in rare case when it is needed.
CLASSPATH=
JAVA_OPTS=
if [ -r "$CATALINA_BASE/bin/setenv.sh" ]; then. "$CATALINA_BASE/bin/setenv.sh"
elif [ -r "$CATALINA_HOME/bin/setenv.sh" ]; then. "$CATALINA_HOME/bin/setenv.sh"
fi
# Add on extra jar files to CLASSPATH
test ".$CLASSPATH" != . && CLASSPATH="${CLASSPATH}:"
CLASSPATH="$CLASSPATH$CATALINA_HOME/bin/bootstrap.jar:$CATALINA_HOME/bin/commons-daemon.jar"
test ".$CATALINA_OUT" = . && CATALINA_OUT="$CATALINA_BASE/logs/catalina-daemon.out"
test ".$CATALINA_TMP" = . && CATALINA_TMP="$CATALINA_BASE/temp"
# Add tomcat-juli.jar to classpath
# tomcat-juli.jar can be over-ridden per instance
if [ -r "$CATALINA_BASE/bin/tomcat-juli.jar" ] ; thenCLASSPATH="$CLASSPATH:$CATALINA_BASE/bin/tomcat-juli.jar"
elseCLASSPATH="$CLASSPATH:$CATALINA_HOME/bin/tomcat-juli.jar"
fi
# Set juli LogManager config file if it is present and an override has not been issued
if [ -z "$LOGGING_CONFIG" ]; thenif [ -r "$CATALINA_BASE/conf/logging.properties" ]; thenLOGGING_CONFIG="-Djava.util.logging.config.file=$CATALINA_BASE/conf/logging.properties"else# Bugzilla 45585LOGGING_CONFIG="-Dnop"fi
fi
test ".$LOGGING_MANAGER" = . && LOGGING_MANAGER="-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
JAVA_OPTS="$JAVA_OPTS $LOGGING_MANAGER"
# Set -pidfile
test ".$CATALINA_PID" = . && CATALINA_PID="$CATALINA_BASE/logs/catalina-daemon.pid"
# Increase the maximum file descriptors if we can
if [ "$cygwin" = "false" ]; thenMAX_FD_LIMIT=`ulimit -H -n`if [ "$?" -eq 0 ]; then# Darwin does not allow RLIMIT_INFINITY on file soft limitif [ "$darwin" = "true" -a "$MAX_FD_LIMIT" = "unlimited" ]; thenMAX_FD_LIMIT=`/usr/sbin/sysctl -n kern.maxfilesperproc`fitest ".$MAX_FD" = ".maximum" && MAX_FD="$MAX_FD_LIMIT"ulimit -n $MAX_FDif [ "$?" -ne 0 ]; thenecho "$PROGRAM: Could not set maximum file descriptor limit: $MAX_FD"fielseecho "$PROGRAM: Could not query system maximum file descriptor limit: $MAX_FD_LIMIT"fi
fi
# ----- Execute The Requested Command -----------------------------------------
case "$1" inrun     )shift"$JSVC" $* \$JSVC_OPTS \-java-home "$JAVA_HOME" \-pidfile "$CATALINA_PID" \-wait 10 \-nodetach \-outfile "&1" \-errfile "&2" \-classpath "$CLASSPATH" \"$LOGGING_CONFIG" $JAVA_OPTS $CATALINA_OPTS \-Djava.endorsed.dirs="$JAVA_ENDORSED_DIRS" \-Dcatalina.base="$CATALINA_BASE" \-Dcatalina.home="$CATALINA_HOME" \-Djava.io.tmpdir="$CATALINA_TMP" \$CATALINA_MAINexit $?;;start   )"$JSVC" $JSVC_OPTS \-java-home "$JAVA_HOME" \-user $TOMCAT_USER \-pidfile "$CATALINA_PID" \-wait 10 \-outfile "$CATALINA_OUT" \-errfile "&1" \-classpath "$CLASSPATH" \"$LOGGING_CONFIG" $JAVA_OPTS $CATALINA_OPTS \-Djava.endorsed.dirs="$JAVA_ENDORSED_DIRS" \-Dcatalina.base="$CATALINA_BASE" \-Dcatalina.home="$CATALINA_HOME" \-Djava.io.tmpdir="$CATALINA_TMP" \$CATALINA_MAINexit $?;;stop    )"$JSVC" $JSVC_OPTS \-stop \-pidfile "$CATALINA_PID" \-classpath "$CLASSPATH" \-Djava.endorsed.dirs="$JAVA_ENDORSED_DIRS" \-Dcatalina.base="$CATALINA_BASE" \-Dcatalina.home="$CATALINA_HOME" \-Djava.io.tmpdir="$CATALINA_TMP" \$CATALINA_MAINexit $?;;version  )"$JSVC" \-java-home "$JAVA_HOME" \-pidfile "$CATALINA_PID" \-classpath "$CLASSPATH" \-errfile "&2" \-version \-check \$CATALINA_MAINif [ "$?" = 0 ]; then"$JAVA_BIN" \-classpath "$CATALINA_HOME/lib/catalina.jar" \org.apache.catalina.util.ServerInfofiexit $?;;*       )echo "Unknown command: \`$1'"echo "Usage: $PROGRAM ( commands ... )"echo "commands:"echo "  run               Start Tomcat without detaching from console"echo "  start             Start Tomcat"echo "  stop              Stop Tomcat"echo "  version           What version of commons daemon and Tomcat"echo "                    are you running?"exit 1;;
esac

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参考资料：
http://tomcat.apache.org/tomcat-7.0-doc/setup.html#Unix_daemon
http://tomcat.apache.org/tomcat-7.0-doc/RUNNING.txt
https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk/bin/daemon.sh
http://ifeve.com/useful-jvm-flags-part-7-cms-collector/

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