From: pnor@btma74.nohost.nodomain
Newsgroups: vmsnet.networks.desktop.pathworks,comp.os.msdos.desqview,comp.sys.ibm.pc.misc
Subject: Does Pathworks co-exist with Desqview.
Date: 14 Aug 92 14:14:33 GMT
Reply-To: pnor@se.alcbel.be
Followup-To: vmsnet.networks.desktop.pathworks
Organization: Alcatel Bell




Hi guys.

Question: does Pathworks co-exist with Desqview, no problems? By design?

I've just been assigned to help fix a problem which is proving to be a
major headache to a colleague of mine. We'd appreciate any insight anyone
can give. By the time I finish this posting it may prove to be moderately
long, but please bear with me.

The scenario is this.

DEC VAXstation 3100 operating as database sevice provider, VMS 5.4-10.
Acer 915 PC (12 Mhz 286 processor) running DOS 5.0, Desqview 2.26,
Pathworks 4.1.
Three programs run on the PC under desqview:
        1. A routing task, which provides message transfer amongst
           co-operating processes, insulating them from things like
           whether another task executes on the same processor or
           not, network setup etc.
        2. A task which sits on the end of the PC's serial link and
           provides a man-machine interface to a process which sits
           at the far end of that link.
        3. A database services provider. This handles simple database
           queries by talking to a VAXstation using Pathworks.

                 -----------------------------------------------
                |                                               |
                |                DESQVIEW + DOS                 |
                |                                               |
                |-----------------------------------------------|
                |                                    |          |
                |         ------------------         |          |
                |        |                  |        |    P     |
  serial line   |        |                  |        |          |       LAN
  ==============|<------>|   ROUTING TASK   |<------>|    A     |==========
                |        |                  |        |          |
                |        |                  |        |    T     |
                |         ------------------         |          |
                |           |           |            |    H     |
                |          /             \           |          |
                |         /               \          |    W     |
                |        /                 \         |          |
                |        |                  |        |    O     |
                |   -----------        -----------   |          |
                |  |           |      |           |  |    R     |
                |  |MAN-MACHINE|      | DATABASE  |  |          |
                |  | INTERFACE |      | PROVIDER  |  |    K     |
                |  |           |      |           |  |          |
                |   -----------        -----------   |    S     |
                |                                    |          |
                 -----------------------------------------------

The problem is this.

With several PCs installed on a test site, every 3 days or so each PC
hangs. The exact time lapse required for the hang to occur is variable,
from hours to days. But eventually it happens. Extensive and careful
investigation has so far not turned up a candidate for the problem.
All three programs running on the PC are home grown and under test,
so are prime candidates for exhibiting a problem, but so far the fault
cannot be laid at the door of any of them.

Without invoking STARTNET.BAT the hang does not happen.
Without the Database Provider and with STARTNET.BAT invoked, it hangs.
It has been observed that the stack of a task can become corrupted; one
instance had a task looping endlessly because of varible corruption. It
appears that any task can be affected, randomly.
A PC has stopped with "Invalid opcode".

A theory.

Pathworks fields an interrupt. It saves current stack status and
switches to its own stack, performs some processing and posts an
event, the result of which will appear later. It restores the stack
and returns from the interrupt. However, in the meantime there is a
window of opportunity which enables Desqview to switch tasks
(e.g clock interrupt supercedes network adapter interrupt), so that
when Pathworks restores the stack status the whole thing blows up.

Hence the original question: does Pathworks co-exist with Desqview?
Does anyone run this combination successfully?
Are there known problems?
Can anyone shed some light on this?
Is Pathworks inherently unstable on a PC with a multitasking OS?

Any information greatfully received. Thanks in advance.

--
Regards

Phil Norris

pnor@se.alcbel.be