How to control execution time of DCL commands

[Robert Gezelter]

Vijay,

As I believe Steve has already commented, the answer is that multiple processes (and as a result, batch jobs) can execute the same command file simultaneously. This presumes that the command file does not use a fixed, fully qualified filename in a way that precludes simultaneous execution.

If a command procedure uses a temporary file TEMPORARY.TMP, then two sessions on the same account will be trying to use the same file. A solution to this is to dynamically create file names using the F$GETJPI lexical function an the PID argument.

The same is true for logical names outside of the process-context.

- Bob Gezelter, http://www.rlgsc.com

[Martin Vorlaender]

Re: What is FEXIT?

I'd think it's a Forced Exit - so it'd be a STOP/IMAGE - rather than a DELPRC, a STOP.

Since STOP/IMAGE wasn't implemented for a long time (pre 7.3-2?), everyone had his own image that called $FORCEX.

$FORCEX would be the right choice IMHO, since the intent is to kill the blocking image runningin the master process, rather than the master process itself.

cu,
Martin

[Hoff]

Not exiting on a timeout is either a bug in your procedure, or a bug in the ftp tool. If you're not using COPY /FTP, start there. The classic FTP utility interface is somewhat more difficult to script than is COPY /FTP.

I don't remember off-hand if COPY /FTP has a qualifier with a timeout specifier; that would be a reasonable enhancement, if not.

Is OpenVMS a prerequisite here or are add-ons permissible? There are hosts that deal with this sort of file transfer operation better (either with built-in tools or with some widely-available add-on software) and that can run parallel and partial-restart ftp transfers. (I'd expect Perl or another existing library has some options here, too. LWP::UserAgent and Net::FTP from libnet come to mind.) Here's a libnet set-up for ftp with a 100 second timeout specified.

use Net::FTP;
my $ftp = new Net::FTP( hostname, Timeout => 100 );

[Jess Goodman]

Yes. "FEXIT" should be replaced with "STOP/IMAGE". Sorry about that, I didn't notice that. As Martin guessed FEXIT was our own implementation of STOP/IMAGE which was required before VMS 7.3.

[John Gillings]

re: Bob:

>If a command procedure uses a temporary
>file TEMPORARY.TMP, then two sessions on
>the same account will be trying to use the
>same file. A solution to this is to
>dynamically create file names using the
>F$GETJPI lexical function an the PID
>argument.

Even better, if you're V7.3 or higher, use F$UNIQUE.

$ myfile=F$PARSE(F$UNIQUE(), "SYS$SCRATCH:.TMP;")

Even better than that is to use PIPE and avoid temporary files altogether.

[Wim Van den Wyngaert]

No f$uniq on my 7.3.

Wim

[labadie_1]

Wim

Let's say Vms 7.3-2 :-)