Re: CMTW (commit wait) on a large number of jobs

Jim, the file is less than 10 MB--when the job runs, it takes a few
seconds. Previous instances of the issue have lasted 20 minutes.

I'm thinking that it may be something to do with commitment control itself,
possibly a serializing of commits. My job in CMTW held other _unrelated_
jobs' commits from completing.

Thanks,
Reeve

On Thu, Jun 19, 2025 at 5:31 AM Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>
wrote:

I’d have a look at the compression parm. That will slow the save down by
orders of magnitude. I somehow doubt it needs to be that compressed.
I’ll bet CPU jumps a bit during that operation as well.


Jim Oberholtzer
Agile Technology Architects

On Jun 19, 2025, at 1:33 AM, Reeve <rfritchman@xxxxxxxxx> wrote:

A customer has been periodically experiencing a backlog of CMTW's at
certain times of the day and we determined the cause was an attempt to

save

a read-only table using this command:
SAVOBJ OBJ(&table) LIB(&datalib) DEV(*SAVF) OBJTYPE(*FILE) +
SAVF(&SAVFLIB/&SAVF) TGTRLS(V7R3M0) UPDHST(*NO) SAVACT(*LIB)

+

DTACPR(*HIGH) SAVACTWAIT(*NOMAX)


The SAVACTWAIT(*NOMAX) is likely the villain...but why when the apps are
just reading?

There were about 1,000 *SHRRD locks on the table in question. I set
commitment control to *CHG. I have WITH *NC on each select. All SQL, of
course. V7R3. The app is a complex, database-heavy pricing service
program used in interactive and batch jobs. I will add PRECHK(*YES)
ACCPTH(*NO).

Even though the backup in question ran every night at 1800, we didn't
always have the problem. There are other unrelated jobs triggering at

1800.

This is a puzzler. Thank you for your insight!

--rf
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