[Info-vax] hung program location

[Tom Adams]

On Feb 19, 6:46 pm, VAXman-  @SendSpamHere.ORG wrote:
> In article <kg0ula$cs... at dont-email.me>, Stephen Hoffman <seaoh... at hoffmanlabs.invalid> writes:
> >On 2013-02-19 22:21:36 +0000, David Froble said:
>
> >> Tom Adams wrote:
>
> >>> There is only one AST programmed in. It's a resource wait AST that
> >>> only fires when the system is telling the process to shutdown, so it
> >>> did not cause the problem.  None of the QIOs or QIOWs use ASTs.
>
> >> If you're using QIO, and don't have a completion AST routine, well, I
> >> know nothing, but I've had the impression that a completion AST routine
> >> is rather normal to signal the completion of the QIO.
>
> >A completion AST routine is common with sys$qio, yes.  It's not
> >necessary, though.  You can easily code the routine to continue running
> >the mainline code with the I/O outstanding and then — some distance
> >forward in the code, when you need to look in the buffer or such —
> >issue the equivalent of sys$synch.  A simple double-buffering scheme
> >can use a pair of sys$qiow calls and a pair of sys$synch calls in a
>
> -------------------^^^^^^^^ SYS$QIO?
>
> >loop, for instance.
>
> --
> VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG
>
> Well I speak to machines with the voice of humanity.

There is a sys$qio with an event flag in the code.  After return from
the sys$qio, the program waits for a logical or of a number of event
flags.  If the question is how we use a sys$qio without an AST,  this
is the answer in the case of this program.