jstatd

jstatd(1)                                                            jstatd(1)



NAME
       jstatd - Virtual Machine jstat Daemon

SYNOPSIS
       jstatd [ options ]


PARAMETERS
       options
          Command-line  options. The options may be in any order. If there are
          redundant or contradictory options, the last option  specified  will
          take precedence.

DESCRIPTION
       The jstatd tool is an RMI server application that monitors for the cre‐
       ation and termination of instrumented  HotSpot  Java  virtual  machines
       (JVMs)  and  provides  a  interface to allow remote monitoring tools to
       attach to JVMs running on the local host.

       The jstatd server requires the presence of an RMI registry on the local
       host.  The  jstatd server will attempt to attach to the RMI registry on
       the default port, or on the port indicated by the -p port option. If an
       RMI registry is not found, one will be created within the jstatd appli‐
       cation bound to the port indicated by the -p  port  option  or  to  the
       default  RMI registry port if -p port is omitted. Creation of an inter‐
       nal RMI registry can be inhibited by specifying the -nr option.

       NOTE: This utility is unsupported and may or may not  be  available  in
       future  versions  of the JDK. It is not currently available on the Win‐
       dows 98 and Windows ME platforms.

OPTIONS
       The jstatd command supports the following options:

       -nr
          Do not attempt to create an internal RMI registry within the  jstatd
          process when an existing RMI registry is not found.

       -p  port
          Port  number  where the RMI registry is expected to be found, or, if
          not found, created if -nr is not specified.

       -n  rminame
          Name to which the remote RMI object is bound in  the  RMI  registry.
          The  default name is JStatRemoteHost. If multiple jstatd servers are
          started on the same host, the name of the exported  RMI  object  for
          each  server  can  be made unique by by specifying this option. How‐
          ever, doing so will require that the unique server name be  included
          in the monitoring client's hostid and vmid strings.

       -Joption
          Pass  option  to  the  java  launcher  called by javac. For example,
          -J-Xms48m sets the startup memory to 48 megabytes. It  is  a  common
          convention  for  -J  to  pass options to the underlying VM executing
          applications written in Java.

SECURITY
       The jstatd server can only monitor JVMs for which it has the  appropri‐
       ate native access permissions. Therefor the jstatd process must be run‐
       ning with the same user credentials as the target JVMs. Some user  cre‐
       dentials, such as the root user in UNIX(TM) based systems, have permis‐
       sion to access the instrumentation exported by any JVM on the system. A
       jstatd process running with such credentials can monitor any JVM on the
       system, but introduces additional security concerns.

       The jstatd  server  does  not  provide  any  authentication  of  remote
       clients. Therefore, running a jstatd server process exposes the instru‐
       mentation export by all JVMs for which the jstatd  process  has  access
       permissions  to any user on the network. This exposure may be undesire‐
       able in your environment and local security policies should be  consid‐
       ered  before  starting  the  jstatd process, particularly in production
       environments or on unsecure networks.

       The jstatd server installs an instance of RMISecurityPolicy if no other
       security  manager  has been installed and therefore requires a security
       policy file to be specified.  The  policy  file  must  conform  to  the
       default policy implementation's Policy File Syntax @
       http://java.sun.com/javase/6/docs/technotes/guides/security/Policy‐
       Files.html.

       The following policy file will allow the jstatd server to run without
       any security exceptions. This policy is less liberal then granting all
       permissions to all codebases, but is more liberal than a policy that
       grants the minimal permissions to run the jstatd server.

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


       To use this policy, copy the text into a file called jstatd.all.policy
       and run the jstatd server as follows:

       jstatd -J-Djava.security.policy=jstatd.all.policy


       For sites with more restrictive security practices, it is possible to
       use a custom policy file to limit access to specific trusted hosts or
       networks, though such techniques are subject to IP addreess spoofing
       attacks. If your security concerns cannot be addressed with a custom‐
       ized policy file, then the safest action is to not run the jstatd
       server and use the jstat and jps tools locally.

REMOTE
       INTERFACE"

       The interface exported by the jstatd process is proprietary and is
       guaranteed to change. Users and developers are discouraged from writing
       to this interface.

EXAMPLES
       Here are some examples of starting jstatd. Note that the jstatd scripts
       automatically start the server in the background.

   Using Internal RMI
       Registry

       This example demonstrates starting jstatd with an internal RMI reg‐
       istry. This example assumes that no other server is bound to the
       default RMI Registry port (port 1099).

       jstatd -J-Djava.security.policy=all.policy


   Using
       External RMI Registry

       This example demonstrates starting jstatd with a external RMI registry.

       rmiregistry&
       jstatd -J-Djava.security.policy=all.policy


       This example demonstrates starting jstatd with an external RMI registry
       server on port 2020.

       rmiregistry 2020&
       jstatd -J-Djava.security.policy=all.policy -p 2020


       This example demonstrates starting jstatd with an external RMI registry
       on port 2020, bound to name AlternateJstatdServerName.

       rmiregistry 2020&
       jstatd -J-Djava.security.policy=all.policy -p 2020 -n AlternateJstatdServerName


   Inhibiting creation of an in-process RMI
       registry

       This example demonstrates starting jstatd such that it will not create
       a RMI registry if one is not found. This example assumes an RMI reg‐
       istry is already running. If it is not, an appropriate error message is
       emitted.

       jstatd -J-Djava.security.policy=all.policy -nr


   Enabling RMI
       logging capabilities.

       This example demonstrates starting jstatd with RMI logging capabilities
       enabled. This technique is useful as a troubleshooting aid or for moni‐
       toring server activities.

       jstatd -J-Djava.security.policy=all.policy -J-Djava.rmi.server.logCalls=true


SEE ALSO
          * java - the Java Application Launcher

          * jps - the Java Process Status Application

          * jstat - the Java Virtual Machine Statistics Monitoring Tool

          * rmiregistry - the Java Remote Object Registry


                                  05 Aug 2006                        jstatd(1)