[Info-vax] Orphaned processes on OpenVMS

[Michael Moroney]

Johnny Billquist <bqt at softjar.se> writes:

>On 2011-05-19 16.47, Snowshoe wrote:
>> On 5/19/2011 6:10 PM, Johnny Billquist wrote:
>>> On 2011-05-19 14.53, Wendell wrote:
...
>>>> I've heard it said that OpenVMS doesn't have this problem at all. How
>>>> does it prevent orphans or at least allow cleanup without rebooting?
>>>
>>> VMS don't have the concept of a hierarchy of processes in the same way
>>> Unix do. But you can kill processes in VMS, just as in Unix.
>>
>> VMS does have subprocesses, and when you kill a main process, its
>> subprocesses WILL die. Subprocesses can have subprocesses as well.

>Well, I didn't say it don't have subprocesses. I just said it don't have 
>a hierarchy in the same way as Unix do.
>And that you can kill processes in either OS. :-)

Yes the process hierarchy is quite different.  Unix has a single tree
while VMS has many parallel trees, most of which consist of a single
(detached) process.  The difference is, and this is what the original
poster was asking about, if a VMS process has subprocesses, the 
subprocesses will be stopped unconditionally when the main processes
is stopped. The process is recursive; if the subprocesses have lower
subprocesses, they will be stopped first.  In Unix, they are not stopped,
but they become owned by the process above it or become orphan
processes.

To answer the original question, if the configuration is a main process
with subprocesses, stopping the main process will stop the subprocesses.
Guaranteed.

Also, the $ STOP process command and its equivalant system service is
a pretty big hammer to stop any process.  If it doesn't stop it, it's
almost certainly a bug in a driver or the operating system that
prevents immediate deletion.