jvmstat介绍

jvmstat Tools Installation

The jvmstat tools distribution is released in both tar and zip formats. There is a single distribution for all supported platforms. These instructions will guide you though the installation process using the Korn Shell on Solaris, Linux, and for the Korn Shell in the MKS Tookit for Windows. Every effort has been made to use shell commands that are compatible with both the Bourne and Korn shells. You may need to adapt these instructions to your preferred shell.

To use the tar archive, you must have atarexecutable on your system. Similarly, to use the zip format, you need to have anunzipexecutable on your system. Thejarcommand can be used in place of theunzipcommand, as jar files are an extension of zip archives. In any case, these instructions assume that the necessary executable can be found in a directory included in the user's PATH environment variable.

In the following instructions, the>character represents the shell's command prompt and the commands you enter to the shell are indicated by text typeset inbold. These instructions will also contain references toJVMSTAT_HOMEandJAVA_HOMEstrings. Although these appear to be environment variables at first glance, they are intended to be substituted with the paths to the installation directories for jvmstat and the Java 2 JDK, respectively. You may choose to create environment variables with these names; however, they are not required for proper installation or operation of the jvmstat tools.

Step 1: Open a shell window

The first step is to open a cmdtool, dtterm, or xterm window. In this windows, set your PATH environment variable to include the directory to the necessary tar, unzip, or jar executable:

>PATH=$PATH:<path to tar/unzip directory>
>export PATH

If you plan to use the jar command in the Java 2 JDK, make sure the bin directory for the JDK is in your PATH:

>PATH=$PATH:JAVA_HOME/bin
>export PATH

The above assumes that a version of the J2SE JRE or JDK is not already found in the user's PATH.

For the MKS Korn shell, the path seperator characher must be changed from the colon character (:), to an escaped semi-colon character (\;). For example:

>PATH=$PATH\;<path to tar/unzip directory>

Step 2: Select Installation Directory

The next step is to select an installation directory. Select any directory for which you have the appropriate permissions to create files and directories. These instructions will assume that you selected/home/userand that thejvmstat-3.0_b03.tarorjvmstat-3.0_b03.zipdistribution file is located in this directory. Installing the jvmstat distribution will result in the creation of ajvmstatsubdirectory containing the entire distribution. The instructions will refer to the/home/user/jvmstatdirectory asJVMSTAT_HOME.

Step 3: Install the jvmstat distribution

To install the distribution, perform. the following steps.

Change your working directory to the installation directory.

>cd /home/user

Verify that either the.zipor.tarjvmstat distribution file is located in the current directory:

>ls -l
-rw-r--r-- 1 user grp 344576 Aug 15 17.38 jvmstat-3.0_b03.tar
-rw-r--r-- 1 user grp 148461 Aug 15 17.38 jvmstat-3.0_b03.zip


Install the distribution.

If you are installing thetarfile, enter the following

>tar xf jvmstat-3.0_b03.tar

If you are installing thezipfile, enter the following

>unzip jvmstat-3.0_b03.zip

These commands will extract the distribution from the archive file and install it in thejvmstatsubdirectory. At this time, the distribution file is no longer needed. You can delete it or move it to another location.

>rm jvmstat-3.0_b03.tar jvmstat-3.0_b03.zip

After the archive files are deleted or moved to a new location, theJVMSTAT_HOMEdirectory will contain the following directories.

>ls -FC jvmstat
bat/ bin/ docs/ etc/ jars/

Step 4: Set Environment Variables

The scripts provided with the jvmstat distribution rely only upon the PATH environment variable. The PATH environment variable must be changed to include the jvmstatbinand the J2SE 5.0 SDKbindirectories. If thejavaexecutable is found in a directory in the PATH other than a J2SE 5.0 SDK, so as the/binor/usr/bindirectories, then the scrupt will not be able to locate thetools.jararchive and will fail to launch the tools.

Set your PATH variable to include the jvmstat and J2SE 5.0 SDK bin directories

>PATH=JVMSTAT_HOME/bin:JAVA_HOME/bin:$PATH
>export PATH

If you are using the MKS Tookit on Windows for your installation, the above commands must be entered as follows.

>PATH=JVMSTAT_HOME/bin\;JAVA_HOME/bin\;$PATH>
>export PATH

Step 5: Install the jstatd policy file

Thejstatdtool is an RMI based server that ships with the J2SE 5.0 SDK and allows the various jvmstat tools to remotely monitor target JVM processes. By default, thejstatdserver installs an instance of the RMI security manager and therefore requires a security policy file. TheJ2SE 5.0jstatddocumentationdescribes a simpile security policy that provides unlimited access to classes loaded from thetools.jararchive.

First, create a file calledjstatd.policyusing your favorite text editor. The file should contain the following text:

Thejstatd.policyfile can reside in any directory you choose. The instructions that follow assume that thejstatd.policyfile is located in the/home/userdirectory.

Step 6: Test the installation

Now that your jvmstat distribution is installed and configured, let's run some tests.

Simple Test

The first test is a simple test that verifies that the bundledjstattool is working as expected. This test runs thejstatcommand such that it attaches to its own JVM, by specifying 0 as thelvmidof the target process, and takes 3 samples of the instrumentation at 1000 millisecond intervals.

>jstat -gcutil 0 1000 3

The output from thejstatcommand should be similar to the output shown above. If an error message or exception is output, then proceed to thetrouble shootingsection below.

Local Test

This test uses thejstatandvisualgccommands to monitor another Java application. In this test, we will start up a Java application, determine itslvmidwith thejpscommand, and then connect to the target JVM with both thejstatandvisualgccommands.

Begin by starting up your target Java application. Any 1.4.2 or later Java application will work. This example uses the Java2Demo application.

>java -jarJAVA_HOME/demo/jfc/Java2D/Java2Demo.jar

Once the target Java application is running, execute thejpscommand from a separate cmdtool, dtterm, or xterm windows and find thelvmidfor the target JVM. Remember, you need to set the PATH environment variable in this new window as described inSet Environment Variablessection above.

>jps
23551 Java2Demo.jar
23581 Jps

It's typical to seeJpslisted in the output of thejpscommand. Next, runjstat, telling it to monitorlvmid23551, taking 3 samples at one second intervals:

>jstat -gcutil 23551 1000 3

The output fromjstatis omitted here; however, it should be similar to the output observed in theSimple Testsection above.

Now, runvisualgctelling it to monitorlvmid23551:

>visualgc 23551

Two or three windows will appear (depending on which garbage collection policy is in effect). The following two windows will appear regardless of the garbage collection policy:

Descriptions of the various panels in these windows are provided in thevisualgc manual page. If an error message or exception is output, then proceed to thetrouble shootingsection below.

Remote test

This test will verify that the remote monitoring functionality is working. This test can be run on one system, but it is better to run it on two systems. For a two system test, you will need to perform. the installation of the jvmstat tools on the second system before proceeding with this test.

For this test, we will assume that the system names aremonitoredfor the system running the target application andmonitoringfor the system running the jvmstat tools.

Onmonitored, startup thejstatdserver and the target Java application. Once again, we will use the Java2Demo application as our target Java application. Thejstatdserver is started as follows:

>jstatd -J-Djava.security.policy=/home/user/jstatd.policy

Now, from a cmdtool, dtterm, or xterm window onmonitoring, run thejpscommand to discover thelvmisof the target Java application. Substitute the name of your monitored system formonitoredin the following commands.

>jps monitored
17869 Java2Demo.jar
17876 Jstatd
17877 Jps

It's typical to see bothJpsandJstatdlisted in the output of thejpscommand. Next, runjstat, telling it to monitorlvmid17869 on the system namedmonitored, taking 3 samples at one second intervals.

>jstat -gcutil 17869@monitored 1000 3

The output fromjstatis omitted here; however, it should be similar to the output observed in theSimple Testsection above.

Now, runvisualgctelling it to monitorlvmid17869 on the system namedmonitored:

>visualgc 17869@monitored

Two or three windows will appear as decribed in theLocal Testsection above.

Terminating Processes

You may want to terminate the processes we started in the above tests. Thejstatdprocess can be terminated as follows:

>kill 17876

Where17876is the process id reported by the nativepscommand or thelvmidreported by thejpscommand as shown above.

Trouble Shooting

If you experience error messages or exceptions from any of the jvmstat tools, check that your PATH variable is set correctly. Also, check themanual pagesfor the tools for proper usage. If these suggestions do not resolve your problems, consult thejvmstat FAQ. If the jvmstat FAQ does not provide a resolution for the problem you are experencing, then send an e-mail tojvmstat-support@sun.com. Please include the J2SE JDK version information (java -version) and the jvmstat version information (visualgc -version) in the e-mail along with a description of the problem you are experiencing.

S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT
  0.00   0.00  37.20  55.10  15.77    106    0.174    58    5.268    5.442
  0.00   0.00  45.87  55.14  15.77    106    0.174    59    5.357    5.531
  0.00   0.00  96.42  55.14  15.77    106    0.174    59    5.357    5.531

grant codebase "file:${java.home}/../lib/tools.jar" {
    permission java.security.AllPermission;
};

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