jstatd -JVM Remote Monitoring(jstat daemon)

In this article we are going to elaborate the jstatd command tool which is a part of JAVA commands (comes with jdk package). This article is the continuation of this previous article.

As we know the standard format of commands in java, the jstatd command also have the format(in command prompt)
jstatd [option]

jstatd is a RMI server application that monitors creation/termination of instrumented JVMs and provides an interface to allow remote monitoring tools to attach to JVMs(running local host). That is why, jstatd server needs and RMI registry at local host. If not found, it will create in jstatd application bound(-p port/ default registry port)

jstatd option: 
-nr : Does not create an internal RMI registry within the jstatd process when an existing RMI registry is not found.
-p [port] : RMI registry port. (if not found, port will be created on, no -nr specified)
-n [rmiName] : Remote RMI object name which is bound in RMI registry(Default is JStatRemoteHost). If multiple jstatd servers are started at a host, RMI object name for each server can unique by this option (the unique server name should be included at monitoring client's hostid and vmid strings).
-J[option] : Pass option to the java launcher

Notes :
-jstatd server and monitor JVMs should be running with same user credentials(for access permissions, better to use root)
-jstatd server does not provide any authentication of remote clients. So, local security policies should be considered before starting jstatd.
-The jstatd server installs an instance of RMISecurityPolicy which requires a security policy(A file to be specified by the default policy implementation's Policy File Syntax. I will explain Java Default Security policy in separate post). To run a policy file in server
jstatd -J-Djava.security.policy=[file location]
-We can use custom policy file for strong security


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