[Info-vax] Nonexisting "Owner process" of a device.

[mcleanjoh at gmail.com]

On Friday, July 7, 2017 at 10:08:48 AM UTC+10, mcle... at gmail.com wrote:
> On Friday, July 7, 2017 at 2:46:46 AM UTC+10, Jan-Erik Soderholm wrote:
> > Hi.
> > 
> > This is something I see from time to time:
> > 
> > $ sh dev TNA8109/fu
> > 
> > Terminal TNA8109:, device type LA120, is online,
> > record-oriented device, carriage control.
> > 
> >   Error count               0  Operations completed           954
> >   Owner process            ""  Owner UIC                     [xx]
> >   Owner process ID   0007547C  Dev Prot         S:RWPL,O:RWPL,G,W
> >   Reference count           3  Default buffer size            132
> > 
> > $ sh proc/id=0007547C
> > %SYSTEM-W-NONEXPR, nonexistent process
> > 
> > Can it be said in general what can cause this?
> > 
> > We get some issues when re-creating the TNA device.
> > The "TELNET /DELETE 8109" command finish but the device
> > is never deleted/removed. The STOP/ID=0007547C gives
> > the same error as the SHOW PROC above.
> > 
> > We do have a work around, but anyway...
> > 
> > Jan-Erik.
> 
> I can see one way that this might happen ...
> 
> Process A requests that some other process (let's call it B) provide an I/O device or channel and then process A terminates without telling process B to deassign the device or channel.
> 
> If this is the case - big IF - then a decent exit handler will help but I'm not sure that there's a 100% certainty that the exit handler will complete. Don't forget that the exit handler will need access to the communication path to process B and something better than co-ordinated read and writes to any mailbox will probably be needed because the exit handler will execute asynchronous.

PS. The last word of the above post should be "asynchronously".  No post-posting edit option here.