Re: Need ideas to reduce open/close in RPG program

[Vinay Gavankar <vinaygav@xxxxxxxxx>]

So if I were to have a subroutine upfront, which does a OPNDBF for all
files with SHARE(*YES), I could leave rest of my program unchanged?

I have following statements already in the program:

Close FILEA;

CMD = 'OVRDBF FILE(FILEA) TOFILE(*LIBL/' +

      FILNAME(S) + ') LVLCHK(*NO) SHARE(*YES)';

CALLP(e)  SYSTEM(CMD : %len(CMD) );
OPEN FILEA;

I could leave all these unchanged and my performance would improve?


On Mon, Dec 14, 2015 at 11:33 AM, Mark Murphy/STAR BASE Consulting Inc. <
mmurphy@xxxxxxxxxxxxxxx> wrote:

> Try shared opens. Someone started down this path, but didn't quite get to
> the end of it. You need a program at the beginning of the process that
> reads through and opens each file in your control file with SHARE(*YES).
> Leave them all open. Now call your current program, and the only change you
> need to make is to set your override to use SHARE(*YES). It will pick up
> the already opened file, and though it is closed by the program, the open
> data path will stay open for the previous program that is holding all the
> files open. The ODP's won't close until all the opens with SHARE(*YES) are
> closed. That won't happen until the job ends.
>
> You could probably even do the initial opens within your RPG program, but
> you will still have to execute the CL commands OVRDBF SHARE(*YES) and
> OPNDBF for each file named in your control file. That will get you open
> data paths without having to link them to your RPG file declaration leaving
> you free to open and close that as many times as you want.
>
> Mark Murphy
> STAR BASE Consulting, Inc.
> mmurphy@xxxxxxxxxxxxxxx
>
>
> -----Vinay Gavankar <vinaygav@xxxxxxxxx> wrote: -----
> To: "RPG programming on the IBM i (AS/400 and iSeries)" <
> rpg400-l@xxxxxxxxxxxx>
> From: Vinay Gavankar <vinaygav@xxxxxxxxx>
> Date: 12/11/2015 06:52PM
> Subject: Need ideas to reduce open/close in RPG program
>
>
> Hi,
>
> We have a program which receives some values thru Data Queue read and it
> updates a file with the values received.
>
> The problem is that there are multiple copies of the file it needs to
> update.
>
> Let us say it is updating FILEA, so that is what is in the compiled code.
>
> On the system there are currently 15 files which are exact copies of this
> file. They have a different file name, but the the same record format name,
> field names etc.
>
> The program reads a 'control' file, which has the names of these 15 files.
> For every file, it does an OVRDBF of FILEA to the actual file name, Opens
> the file, updates/writes the record, and then Closes the File.
>
> The system was built for 'flexibility' years back, when they started with 2
> or 3 files. It is flexible, in the sense it did not need a code change as
> the files being updated grew from 3 to 15.
>
> This is a very 'busy' program, meaning it is constantly receiving data thru
> the data queue. Actually there are multiple copies of this program running
> simultaneously receiving data from the same data queue and all of them are
> pretty busy.
>
> Now they are finding that all these open/closes are seriously impacting the
> CPU usage.
>
> An architectural change is obviously indicated, but that would take time to
> implement.
>
> As usual, they are looking for a 'short term', quick and dirty fix (to be
> implemented in 2 weeks) to eliminate these open/close.
>
> The only thing we could think of was to define the current 15 files
> separately in the program and then update them as needed, losing all
> flexibility.
>
> Any other ideas or suggestions would be greatly appreciated.
>
> TIA
> --
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