详解Tomcat调优和Tomcat监控
tomcat调优
vi catalina.sh

Control Script for the CATALINA Server

Environment Variable Prerequisites

Do not set the variables in this script. Instead put them into a script

setenv.sh in CATALINA_BASE/bin to keep your customizations separate.

CATALINA_HOME May point at your Catalina "build" directory.

CATALINA_BASE (Optional) Base directory for resolving dynamic portions

of a Catalina installation. If not present, resolves to

the same directory that CATALINA_HOME points to.

CATALINA_OUT (Optional) Full path to a file where stdout and stderr

will be redirected.

Default is $CATALINA_BASE/logs/catalina.out

CATALINA_OPTS (Optional) Java runtime options used when the "start",

"run" or "debug" command is executed.

Include here and not in JAVA_OPTS all options, that should

only be used by Tomcat itself, not by the stop process,

the version command etc.

Examples are heap size, GC logging, JMX ports etc.

CATALINA_TMPDIR (Optional) Directory path location of temporary directory

the JVM should use (java.io.tmpdir). Defaults to

$CATALINA_BASE/temp.

JAVA_HOME Must point at your Java Development Kit installation.

Required to run the with the "debug" argument.

JRE_HOME Must point at your Java Runtime installation.

Defaults to JAVA_HOME if empty. If JRE_HOME and JAVA_HOME

are both set, JRE_HOME is used.

JAVA_OPTS (Optional) Java runtime options used when any command

is executed.

Include here and not in CATALINA_OPTS all options, that

should be used by Tomcat and also by the stop process,

the version command etc.

Most options should go into CATALINA_OPTS.

JAVA_ENDORSED_DIRS (Optional) Lists of of colon separated directories

containing some jars in order to allow replacement of APIs

created outside of the JCP (i.e. DOM and SAX from W3C).

It can also be used to update the XML parser implementation.

Note that Java 9 no longer supports this feature.

Defaults to $CATALINA_HOME/endorsed.

JPDA_TRANSPORT (Optional) JPDA transport used when the "jpda start"

command is executed. The default is "dt_socket".

catalina这个脚本会读取很多参数：

CATALINA_HOME tomcat的安装目录

CATALINA_BASE tomcat的工作目录

如果我们想要运行Tomcat的 多个实例，但是不想安装多个Tomcat软件副本。那么我们可以配置多个工作目录，每个运行实例独占一个工作目录，但是共享同一个安装目录。

CATALINA_OPTS catalina运行时的参数 heap size 、GC logging、JMX ports etc

JAVA_OPTS java运行时的参数 heap size 、GC logging、JMX ports etc

两者的区别：

在Tomcat的catalina.sh文件中的启停server脚本中都应用到了两个变量： CATALINA_OPTS和JAVA_OPTS。用于保存Tomcat运行所需的各种参数。

他们在文件中的注释如下：

（可选）Java 执行"start","stop"或"run"命令时用到的运行时参数； [JAVA_OPTS]

（可选）Java 执行"start"或"run"命令时用到的运行时参数； [CATALINA_OPTS]

那么，为什么有两个不同的变量？他们有什么区别？

首先，定义在这两个变量中的参数都会被传递到启动Tomcat的命令：“start"和"run”，只有定义在JAVA_OPTS中的参数会被传递到"stop"命令。

所以将参数定义到哪个变量中并不影响Tomcat的启动和运行，而只影响到了Tomcat的运行结束。

第二种区别更加微妙。其他应用程序也可以使用JAVA_OPTS，但Tomcat只会用到CATALINA_OPTS。所以如果你只使用了Tomcat，在设置环境变量时，你最好使用CATALINA_OPTS，而如果你同时也用到了其他java应用程序，如JBoss，在设置环境变量时你应该使用JAVA_OPTS。

if $cygwin; then
[ -n "$JAVA_HOME" ] && JAVA_HOME=cygpath --unix "$JAVA_HOME"
[ -n "$JRE_HOME" ] && JRE_HOME=cygpath --unix "$JRE_HOME"
[ -n "$CATALINA_HOME" ] && CATALINA_HOME=cygpath --unix "$CATALINA_HOME"
[ -n "$CATALINA_BASE" ] && CATALINA_BASE=cygpath --unix "$CATALINA_BASE"
[ -n "$CLASSPATH" ] && CLASSPATH=cygpath --path --unix "$CLASSPATH"
fi
发现脚本是可以自动获取这些值的

exec "$_RUNJDB" "$LOGGING_CONFIG" $LOGGING_MANAGER $JAVA_OPTS $CATALINA_OPTS
-D$ENDORSED_PROP="$JAVA_ENDORSED_DIRS"
-classpath "$CLASSPATH"
-sourcepath "$CATALINA_HOME"/../../java
-Djava.security.manager
-Djava.security.policy=="$CATALINA_BASE"/conf/catalina.policy
-Dcatalina.base="$CATALINA_BASE"
-Dcatalina.home="$CATALINA_HOME"
-Djava.io.tmpdir="$CATALINA_TMPDIR"
org.apache.catalina.startup.Bootstrap "$@" start
根据这些参数$JAVA_OPTS $CATALINA_OPTS 来启动tomcat

所以只需要在前面添加：

例如：

//其他的参数也同理
export JAVA_OPTS="-Xms:100m -Xmx:2048m"
后面会自动读取

tomcat监控

jps
xxxx Bootstrap
//1s打印一次
jstat -gc xxxx 1s