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Sachinincsc
New User
Joined: 01 Oct 2008
Posts: 11
Location: Philadelphia, USA
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| How Does SYSOUT = DUMMY helps in performance. Would it be same if i comment all the Displays in the code ?? |
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enrico-sorichetti
Superior Member
Joined: 14 Mar 2007
Posts: 10873
Location: italy
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from a pure performance point of view
taking away things ( displays in this case ) is the most appropriate action
DUMMYfying an output saves a bit of time and dasd space from a pure
data management point of view |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
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| How Does SYSOUT = DUMMY helps in performance. |
Who says it does? The only thing dd dummy "saves" is physical i/o and spool/dasd space. All of the work required to get to the point of the i/o is still done.
So, if a process reads a few million rows of some database tables to create a 200 line summary report and the report is assigned to dd dummy, tyhe savings is practically non-existent.
| Quote: |
| Would it be same if i comment all the Displays in the code |
The resulting output would be the same, but the resources needed would not change enough to measure.
On the other hand, if you have a process that writes millions of records to a qsam file and also produces a summary report and for debugging purposes you need to create the summary report, assigning the output qsam file to dd dummy will save considerable resources.
Do you have something more specific in mind? |
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Sachinincsc
New User
Joined: 01 Oct 2008
Posts: 11
Location: Philadelphia, USA
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Thanks
I got my Answer and My collegues tooooooooo |
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Marso
REXX Moderator
Joined: 13 Mar 2006
Posts: 1353
Location: Israel
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To suppress my debugging displays, I usualy use this feature:
| Code: |
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. IBM-370 WITH DEBUGGING MODE. |
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D DISPLAY '=DBG=> CODE=' WS-CODE ' - PAGE=' WS-PAGE
D ' - DATE=' WS-DATE |
At compile time:- When SOURCE-COMPUTER is WITH DEBUGGING MODE,
the "D" in column 7 is considered as a space: the DISPLAY is part of the program and will be executed.
- When the SOURCE-COMPUTER line is commented,
the "D" in column 7 is considered as a comment, the DISPLAY will not be executed.
Only drawback (as far as I know): you have to recompile the program to hide/restore the "D" lines. |
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Robert Sample
Global Moderator
Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA
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I code this as
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SOURCE-COMPUTER. IBM-370
* WITH DEBUGGING MODE
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so I just have to take the asterisk out of column 7 to change the program behavior. Note the period is on the third line, just past and underneath MODE. |
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