HP Driver for JDBC User's Manual

66 AppendixB

JDBC Monitor

HP-UX Monitor

On the HP-UX platform, a separate server-process services each client

connection. These processes are dissociated from the monitor process,

so if the monitor terminates or dies, the existing server-processes

servicing client requests will continue to function, until the client closes

the connection, or the server times out.

Normally, the monitor is automatically started up during the host boot

process via a startup script. This startup script is installed when the

HP JDBC product is installed on the server. Normally, the monitor is

never brought down unless the machine is brought down, in which case

it will be automatically stopped via a stop script that is installed along

with the startup script.

If there is a need to start or shut down the monitor when the host

machine is still up and running, the tool monctrl (also installed with

the HP JDBC product) can be used to perform the startup and shut

down. The command to use monctrl is:

monctrl {start|reset|kill} [

portnumber

]

The “start” argument will start up the monitor on either the default

port number or on the speciﬁed port number. The “kill” argument will

ﬁrst terminate each of the monitor’s active child processes, and then

terminate the monitor process itself. Doing this gives a better chance of

being able to restart the monitor once it has been shut down. The

portnumber

argument is optional, if it is not speciﬁed the default port

number will be used.

NOTE

monctrl should only be executed by “root” because the monitor must

run as “root” to allow it to spawn processes and set user ids. If it is not

started by “root,” other users will not be able to connect to the monitor.

The “reset” argument is discussed in the section dealing with the

monitor conﬁguration ﬁle.

You cannot start a monitor on the same port number as a currently

running monitor. You also can not restart a monitor on its original port

number until all child processes that were spawned by the previous

monitor process are terminated, and the port released. If the monitor is

intentionally terminated or accidentally terminates, all of its child

processes must be terminated before it can be restarted. For this

reason, the monitor must not be terminated by using the UNIX kill

command. Always use the monctrl tool to kill the monitor. The tool will

search out all the child processes and kill them ﬁrst, before killing the

monitor.