Reducing the Operating System Priority of PeopleSoft Processes

I wrote about controlling the operating system priority of processes in PeopleSoft Tuxedo domains in Chapters 13 of 14 of PeopleSoft for the Oracle DBA, but I think it is worth a note here.

On Linux and Unix systems, the nice command can be used to lower the operating system scheduling priority of a process (or a privileged can increase the priority). When a server has no free CPU, processes with a lower priority get less time on the CPU. However, when there is free CPU available, the scheduling priority does not affect the amount of CPU that the process can utilise. 

On Unix, the priority of a Tuxedo server process can be adjusted using the -n server command line option in the configuration. The parameters to this option are simply passed through to the nice(2) function. Hence, this option does not work on Windows.

PSPRCSRV        SRVGRP=BASE
                SRVID=101
                MIN=1
                MAX=1
                RQADDR="SCHEDQ"
                REPLYQ=Y
                CLOPT="-n 4 -sInitiateRequest -- -C psprcs.cfg -CD HR88 -PS PSUNX -A start -S PSPRCSRV"

The operating system priority of a process is inherited from its parent. Therefore, lowering the priority of the Process Scheduler running under Tuxedo will also lower the priority of the batch processes that it spawns. 

• Therefore Stand-alone Application Engine processes (psae) and Cobol processes inherit the priority of the process scheduler server process (PSPRCSRV).
• However, if the Application Engine server process (PSAESRV) is used, its priority can be set directly. 

There are some potential uses for this approach.

• If the process scheduler is co-resident with the application server, then it could be run at a lower priority to ensure the online users get preferential allocation of CPU, and that online performance does not suffer excessively at the hands of the batch.
• A system might have two websites: one for self-service and the other for the 'back-office' users. You could configure separate application servers for each site, and run the self-service application server is run at a lower priority. 

In PeopleSoft, I prefer to create additional variables in the configuration file (psprcs.cfg).

[Process Scheduler]
;=========================================================================
; General settings for the Process Scheduler
;=========================================================================
PrcsServerName=PSUNX
;-------------------------------------------------------------------------
;Reduce priority of Process Scheduler server process, set to 0 if not needed
Niceness=4
...

From PeopleTools 8.4, the Application Engine server process is configured by default. The priority of the AE server processes can then be controlled independently of the process scheduler by creating a separate variable in the PSAESRV section of the configuration file.  However, it is generally better to use standalone PSAE, unless you have many short-lived application engine processes, as in CRM (see Application Engine in Process Scheduler: PSAESRV Server Process -v- Standalone PSAE executable).   

[PSAESRV]
;=========================================================================
; Settings for Application Engine Tuxedo Server
;=========================================================================
;-------------------------------------------------------------------------
;Reduce priority of application engine server process, set to 0 if not needed
Niceness=5
...

In this example, I have reduced the priorities of both the process scheduler and AE servers, but the process scheduler is left with a higher priority than the AE servers. The new variables can then be referenced Tuxedo template file (psprcsrv.ubx).

{APPENG}
#
# PeopleSoft Application Engine Server
#
PSAESRV         SRVGRP=AESRV
                SRVID=1
                MIN={$PSAESRV\Max Instances}
                MAX={$PSAESRV\Max Instances}
                REPLYQ=Y
                CLOPT="-n {$PSAESRV\Niceness} -- -C {CFGFILE} -CD {$Startup\DBName} -S PSAESRV"
{APPENG}
...
PSPRCSRV        SRVGRP=BASE
                SRVID=101
                MIN=1
                MAX=1
                RQADDR="SCHEDQ"
                REPLYQ=Y
                CLOPT="-n {$Process Scheduler\Niceness} -sInitiateRequest -- -C {CFGFILE} -CD {$Startup\DBName} -PS {$Process Scheduler\PrcsServerName} -A start -S PSPRCSRV"

When the domain is configured in psadmin, the variables are resolved in the Tuxedo configuration file (psprcsrv.ubb).  The -n option can be seen in the server command-line options (CLOPT).

#
# PeopleSoft Application Engine Server
#
PSAESRV         SRVGRP=AESRV
                SRVID=1
                MIN=1
                MAX=1
                REPLYQ=Y
                CLOPT="-n 5 -- -C psprcs.cfg -CD HR88 -S PSAESRV"
...
PSPRCSRV        SRVGRP=BASE
                SRVID=101
                MIN=1
                MAX=1
                RQADDR="SCHEDQ"
                REPLYQ=Y
                CLOPT="-n 4 -sInitiateRequest -- -C psprcs.cfg -CD HR88 -PS PSUNX -A start -S PSPRCSRV"