[Info-vax] Cobol: Faster flushing of buffer to sequential file

[Hein RMS van den Heuvel]

On Feb 5, 9:50 am, Neil Rieck <n.ri... at sympatico.ca> wrote:
> On Jan 13, 1:03 pm, snake <ythe... at gmail.com> wrote:

> I have never used COBOL since leaving school so take the next bit of

This has little or nothing to do with Cobol/Basic/Fortran and
everything with RMS
Actually, with Cobol and C, an un-shared simple sequential file will
be handled in the Language RTL.
As such few(er) SYS$WRITE(s) will be used versus a  SYS$PUT per record
with the CMEXEC and RMS rab/rab checking that entails.
That is typically a CPU win.
The price is that RMS has not 'seen' the data yet, and STOP/ID
($DELPRC) will not be able to flush out dirty buffers/
STOP/IMAGE ($FORCEX) will trigger RTL rundown which will flush out
best it can.

Btw... still using Richard;s example but modified to OPEN OUTPUT
MY_FILE, to test the above the force exit creates an 'interesting'
error:


Hit <return> to continue. . .
%COB-F-CLOSE_ERROR, unknown error during CLOSE SYS$INPUT:.;
-RMS-E-ACT, file activity precludes operation
%TRACE-F-TRACEBACK, symbolic stack dump follows
:


> In HP-BASIC for OpenVMS, if you open an RMS file without using the
> keyword ALLOW then it will default to ALLOW NONE. What this means is
> your writing process wont flush the buffer to disk until:
>
> 1) you CLOSE the file -OR-
> 2) or the write buffer becomes 100% (full)

right

>
> Changing the open statement to either ALLOW READ or ALLOW MODIFY
> causes write data to flush to disk immediately.

right, as I wrote earlier. I would not use the word flush when you
mean write as it is 'overloaded'

> (ALLOWING READERS, ALLOWING WRITERS, ALLOWING ALL). Maybe these
> clauses will do for you in COBOL what BASIC did for me.

Of course they do. That's all RMS.

:-)

Hein.