Spooler Plus Programmer's Guide

Using the Spooler Print Procedures, Print Processes, and

Perusal Processes

Spooler Plus Programmer’s Guide—522293-003

3-8

Combining Data Retrieval With Spooler Communication

A print process must perform the tasks of retrieving and printing jobs and responding to

supervisor messages concurrently. This can be accomplished in any manner that you

find convenient. The only limitation is that a print process must respond to a

supervisor message within 10 minutes. However, it is important that the print process

respond as quickly as possible because the supervisor cannot do any useful work until

it gets a response.

To maximize print process responsiveness to Spoolcom commands, however, the file

to the supervisor should be checked for completion following the writing of every line of

data. HP recommends that you use the following procedure:

1. Open each device with nowait I/O. After each write to a device, monitor

completion on any file with AWAITIO[X].

2. If a device has finished, the print process calls PRINTREAD to get the next line of

data for the job printing on that device and starts an I/O operation on the device.

3. If the file to the supervisor finishes, the print process calls PRINTCOMPLETE and

PRINTREADCOMMAND to obtain the message and executes the supervisor

instruction.

After executing the supervisor instruction, the print process loops back to AWAITIO[X].

Debugging Print Processes

To debug a print process using the interactive debugging facility Debug (described in

the Debug Manual), the subcommand DEBUG is specified at the time the print process

is initialized with the Spoolcom PRINT command:

)PRINT $trial, FILE $yrvol.yrsub.pproc, PRI 145, DEBUG

The DEBUG subcommand causes the print process to run in Debug mode, which has

two effects:



The print process immediately enters the Debug state upon being started by the

supervisor. The Debug facility prompts the terminal where the supervisor was run.



The supervisor does not time out the print process if the print process fails to

respond to a message within 10 minutes.

To interactively debug a print process, follow this procedure:

1. Coldstart or warmstart a spooler, initializing the print process with the DEBUG

subcommand.

Note. As long as a job is being printed, there is always an operation on the device outstanding after a

supervisor instruction has been executed.

Note. Start a separate spooler dedicated solely to debugging your print process. Because the

supervisor waits indefinitely for message responses from a print process in Debug mode, the

spooler halts when a print process is being debugged.