1jstatd(1) General Commands Manual jstatd(1)
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6 jstatd - Virtual Machine jstat Daemon
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9 jstatd [ options ]
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13 options
14 Command-line options. The options may be in any order. If there are
15 redundant or contradictory options, the last option specified will
16 take precedence.
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19 The jstatd tool is an RMI server application that monitors for the cre‐
20 ation and termination of instrumented HotSpot Java virtual machines
21 (JVMs) and provides a interface to allow remote monitoring tools to
22 attach to JVMs running on the local host.
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24 The jstatd server requires the presence of an RMI registry on the local
25 host. The jstatd server will attempt to attach to the RMI registry on
26 the default port, or on the port indicated by the -p port option. If an
27 RMI registry is not found, one will be created within the jstatd appli‐
28 cation bound to the port indicated by the -p port option or to the
29 default RMI registry port if -p port is omitted. Creation of an inter‐
30 nal RMI registry can be inhibited by specifying the -nr option.
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32 NOTE: This utility is unsupported and may or may not be available in
33 future versions of the JDK. It is not currently available on the Win‐
34 dows 98 and Windows ME platforms.
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37 The jstatd command supports the following options:
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39 -nr
40 Do not attempt to create an internal RMI registry within the jstatd
41 process when an existing RMI registry is not found.
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43 -p port
44 Port number where the RMI registry is expected to be found, or, if
45 not found, created if -nr is not specified.
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47 -n rminame
48 Name to which the remote RMI object is bound in the RMI registry.
49 The default name is JStatRemoteHost. If multiple jstatd servers are
50 started on the same host, the name of the exported RMI object for
51 each server can be made unique by by specifying this option. How‐
52 ever, doing so will require that the unique server name be included
53 in the monitoring client's hostid and vmid strings.
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55 -Joption
56 Pass option to the java launcher called by javac. For example,
57 -J-Xms48m sets the startup memory to 48 megabytes. It is a common
58 convention for -J to pass options to the underlying VM executing
59 applications written in Java.
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62 The jstatd server can only monitor JVMs for which it has the appropri‐
63 ate native access permissions. Therefor the jstatd process must be run‐
64 ning with the same user credentials as the target JVMs. Some user cre‐
65 dentials, such as the root user in UNIX(TM) based systems, have permis‐
66 sion to access the instrumentation exported by any JVM on the system. A
67 jstatd process running with such credentials can monitor any JVM on the
68 system, but introduces additional security concerns.
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70 The jstatd server does not provide any authentication of remote
71 clients. Therefore, running a jstatd server process exposes the instru‐
72 mentation export by all JVMs for which the jstatd process has access
73 permissions to any user on the network. This exposure may be undesire‐
74 able in your environment and local security policies should be consid‐
75 ered before starting the jstatd process, particularly in production
76 environments or on unsecure networks.
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78 The jstatd server installs an instance of RMISecurityPolicy if no other
79 security manager has been installed and therefore requires a security
80 policy file to be specified. The policy file must conform to the
81 default policy implementation's Policy File Syntax @
82 http://java.sun.com/javase/6/docs/technotes/guides/security/Policy‐
83 Files.html.
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85 The following policy file will allow the jstatd server to run without
86 any security exceptions. This policy is less liberal then granting all
87 permissions to all codebases, but is more liberal than a policy that
88 grants the minimal permissions to run the jstatd server.
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90 grant codebase "file:${java.home}/../lib/tools.jar" {
91 permission java.security.AllPermission;
92 };
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95 To use this policy, copy the text into a file called jstatd.all.policy
96 and run the jstatd server as follows:
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98 jstatd -J-Djava.security.policy=jstatd.all.policy
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101 For sites with more restrictive security practices, it is possible to
102 use a custom policy file to limit access to specific trusted hosts or
103 networks, though such techniques are subject to IP addreess spoofing
104 attacks. If your security concerns cannot be addressed with a custom‐
105 ized policy file, then the safest action is to not run the jstatd
106 server and use the jstat and jps tools locally.
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109 INTERFACE"
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111 The interface exported by the jstatd process is proprietary and is
112 guaranteed to change. Users and developers are discouraged from writing
113 to this interface.
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116 Here are some examples of starting jstatd. Note that the jstatd scripts
117 automatically start the server in the background.
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119 Using Internal RMI
120 Registry
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122 This example demonstrates starting jstatd with an internal RMI reg‐
123 istry. This example assumes that no other server is bound to the
124 default RMI Registry port (port 1099).
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126 jstatd -J-Djava.security.policy=all.policy
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129 Using
130 External RMI Registry
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132 This example demonstrates starting jstatd with a external RMI registry.
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134 rmiregistry&
135 jstatd -J-Djava.security.policy=all.policy
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138 This example demonstrates starting jstatd with an external RMI registry
139 server on port 2020.
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141 rmiregistry 2020&
142 jstatd -J-Djava.security.policy=all.policy -p 2020
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145 This example demonstrates starting jstatd with an external RMI registry
146 on port 2020, bound to name AlternateJstatdServerName.
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148 rmiregistry 2020&
149 jstatd -J-Djava.security.policy=all.policy -p 2020 -n AlternateJstatdServerName
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152 Inhibiting creation of an in-process RMI
153 registry
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155 This example demonstrates starting jstatd such that it will not create
156 a RMI registry if one is not found. This example assumes an RMI reg‐
157 istry is already running. If it is not, an appropriate error message is
158 emitted.
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160 jstatd -J-Djava.security.policy=all.policy -nr
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163 Enabling RMI
164 logging capabilities.
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166 This example demonstrates starting jstatd with RMI logging capabilities
167 enabled. This technique is useful as a troubleshooting aid or for moni‐
168 toring server activities.
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170 jstatd -J-Djava.security.policy=all.policy -J-Djava.rmi.server.logCalls=true
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174 * java - the Java Application Launcher
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176 * jps - the Java Process Status Application
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178 * jstat - the Java Virtual Machine Statistics Monitoring Tool
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180 * rmiregistry - the Java Remote Object Registry
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183 05 Aug 2006 jstatd(1)