jstatd(1)jstatd(1)NAMEjstatd - Virtual Machine jstat Daemon
SYNOPSISjstatd [ options ]
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
application 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 J2SE SDK. It is not currently available on the
Windows 98 and Windows ME platforms.
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.
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 speci‐
fied.
-n rminame Name to which the remote RMI object is bound in the RMI
registry. The default name is JStatRemoteHost. If multi‐
ple 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. However, 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 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. The policy file
can be specified with the -J-Djava.security.policy=file
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, Sun recommends that
the jstatd security policy be customized to meet your specific needs.
The jstatd server can only monitor JVMs for which it has the appropri‐
ate access permissions. However, jstatd does not perform any user level
authentication or authorization checking. Therefore, it opens access
to the instrumentation exported by the JVMs for which the jstatd server
has the appropriate access permissions, allowing arbitrary users on the
network to monitor JVMs that might otherwise be inaccessible. Such
exposure may be unacceptable in your environment. Particular care
should be exercised when running the jstatd server with credentials
that allow wide exposure, such as running the server with root permis‐
sions on UNIX based systems.
The exposure introduced by the jstatd server can be eliminated by not
running the server, thus requiring all monitoring activities to be per‐
formed locally. Alternatively, the security policy file can be custom‐
ized to limit access to specific trusted hosts.
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-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
This example uses the Bourne Shell syntax for setting environment vari‐
ables, other shells or command interpreters may require different syn‐
tax.
SEE ALSOjava(1)jps(1)jstat(1)rmiregistry(1)
13 June 2004 jstatd(1)
