Communicator e3000 MPE/iX Release 6.5 (Non-Platform Software Release C.65.00 (30216-90291)

74 Chapter3

Growth Solution

NEWCI Command (CI Elimination)

by Scott McClellan

Commercial Systems Division

MPE/iX Release 6.5 supports a new command called NEWCI. The NEWCI command is similar

to the pre-existing RUN command in that it is used to execute a program. Every time a

program executes, a new process is created. A process can be deﬁned as an “independent

instance or execution of a program”. Both the NEWCI and RUN commands create a new

process. The RUN command creates the new process as a child of the process that invoked

the RUN command. In the case of the NEWCI command, the new process replaces the

MPE/iX Command Interpreter (CI) process for that session. Hence the name of the

command. NEWCI is used to create a new CI process that replaces the old CI process.

The sole purpose of the NEWCI command is to reduce the number of processes by the system

per session logon. It is intended for use on heavily loaded, high-end systems. The target

customer environment is discussed in more detail below. Other than saving one process per

user, the NEWCI command does not provide any additional functionality over the RUN

command.

Background Information

The maximum number of concurrent processes is ﬁxed for a given release of the operating

system. Hewlett-Packard periodically makes enhancements to the MPE/iX to support more

concurrent processes. Nevertheless, on high-end heavily loaded systems, processes can be

a relatively scarce resource - potentially limiting the maximum number of users on that

system. The maximum number of concurrent processes has not been increased in Release

6.5 and it remains 8190.

Processes are used anytime a program is executing. The operating system itself is a

collection of programs (sometimes referred to as system programs). Every time a user logs

on to the system several processes are used, a minimum of two processes for system

programs, and additional processes for any programs executed by the user. One of the

processes that is associated with every user’s logon is the Command Interpreter (CI)

process. The MPE/iX operating system comes with a standard program which reads and

executes commands for the user. The standard MPE/iX CI is found in the program ﬁle

CI.PUB.SYS.

In production environments, most system administrators set up their systems so that

users have no direct access to the standard MPE/iX CI. This is typically done by creating

some kind of logon UDC that will automatically execute the appropriate application for the

user. Such logon UDCs typically disable the BREAK key (using OPTION NOBREAK). The end

result is a production environment that is easier for users (because they do not have to be

trained on how to ﬁnd and run programs, set up ﬁle equations, etc), and easier for system

administrators to keep secure (because users have no access to CI commands).

Logon UDCs typically use the RUN command to execute the user’sapplication program. The

NEWCI command provides an alternative to the RUN command which will result in saving

one process per user. The critical difference between the RUN command and the NEWCI

command is that the RUN command creates the speciﬁed program as a child process which