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

[mcleanjoh at gmail.com]

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.