Spool work processes ("SPO") read spools, convert them to Page Description Language, and finally send them to printers over the network. If several spool work processes have been defined in SAP system, spools may arrive at the printer in a different sequence.
You may use the following remarks to make spools printed sequentially.
- "Process requests sequentially" is a flag that may be defined for output devices: This flag is only used when there are several SPO work processes to ensure 2 successive spools are processed sequentially. When there is one SPO WP, it is always processed sequentially.
When selected, only one SPO work process can process the output requests of a given output device. It works only if the server-internal job queue (SAP Note 118057 below) does not overflow (there are 50 output requests in rspo/global_shm/job_list profile parameter by default ( SAP Note 412065 below)), and only if SPO work processes are not restarted (SAP Note 776933 below).
Note: spools are available to SPO work processes only when the generator program does a COMMIT WORK (SAP Note 855342 below)
SAP Note 118057 - Flexible Configuration of the Spool Service: this note contains much information about how spooling works. It contains the following chapters:
- Arranging the Spool Service of an Instance (Separate Administration of a Request Queue, Output Requests with Priorities, Queue overflow)
- Central Administrative Actions (Multiple Spool Work Processes, Querying the Status at the Host Spool Systems, Problems with Printing in Order of generation (Accepting Requests, Printing in Order-of-Generation, Reserving Work Processes, Output Devices Printing Requests in the Order they Were Generated))
- Flexible Configuration of Server Architecture
- Classifying Spool Servers and Output Devices
- Logical Servers
- Alternate Servers
- Queues and Caches
- Spool Request Queue
- Device Cache
- Host Spool Request List
- Server Cache
SAP Note 412065 - Incorrect output sequence of output requests: sequential processing works only if the server-internal job queue ( see SAP Note 118057 ) does not overflow, there are 50 output requests in rspo/global_shm/job_list profile parameter by default
SAP Note 776933 - "Sequential order processing" does not seem to work.: when a printer has "process requests sequentially" and you use 2 SPO work process and restart them automatically using rdisp/wp_auto_restart, though the output request remains in the same SPO, the order may be lost because it is sorted further back in the queue due to the delay in the receipt of the message triggered by the restart.
SAP Note 855342 - Sequential processing: Help for the analysis: "Conclusion: If you expect sequence reliability, the spool requests must be created sequentially by the application program in an SAP process. Only then is it ensured that the print notifications sent at the time of the COMMIT WORK will also arrive in exactly this sequence at the SPO"
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