Powerhouse locking & 3gl compatibility

[Chris Sharman]

We're using Alpha OpenVMS 7.1, PH 7.10.G3, RMS.

We've been experiencing a certain amount of 'flakiness' in locking, both in
Quick and in related 3gl programs, which I think I've finally understood &
resolved.

Symptoms include 'record has changed since you found it', when it shouldn't be
able to; and duplicates in sequential numbering, when, again, it shouldn't be
possible.

We were using Powerhouse file locks, through the Quick lock file verb and the
DALOCK routines, but I now know that this technique is flawed, and, I believe,
redundant.

The effective approach would appear to be Quick lock record & normal RMS record
locks; or, if a file lock is really needed, an exclusive or semiexclusive open.
The flaw in Powerhouse file locks is that they are group, not system-wide.
Powerhouse record locks are not Powerhouse specific, but are normal RMS record
locks, and so do not experience the problem.

I've written a demo 3gl program which simply uses RMS $get, and not the DALOCK
routines, but which provokes the "waiting on lock ..." message from a quick
screen.

Anyone else out there using DALOCK, with good or bad results, on VMS or another
platform ? Or lock file ?

Regards,
Chris
_______________________________________________________________________
Chris.Sharman@CCAgroup.co.uk		http://www.ccastat.demon.co.uk/
CCA Stationery Ltd, Eastway, Fulwood, Preston, Lancashire, PR2 9WS.
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Subscribe: "subscribe powerh-l" in message body to majordomo@lists.swau.edu
Unsubscribe: "unsubscribe powerh-l" in message to majordomo@lists.swau.edu
This list is closed, thus to post to the list, you must be a subscriber.