Re: Runaway processes on disconnect (465 Views)
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Occasional Visitor
BFisher
Posts: 1
Registered: ‎10-21-2013
Message 1 of 10 (675 Views)

Runaway processes on disconnect

Hi,

 

We use Esker's Smarterm app to emulate VT420 terminals on our Open/VMS Ingerity system.  I'll admit that we do have training issue here, however when our staff disconnect from VMS by clicking the "X" on the terminal emulation app, without logging off VMS first, we get runaway processes that chew up a very high percentage of our CPU.

 

We have devised a script to kill these runaway processes,but we would prefer not to get them in the first place. 

 

Would appreciate any insights into what might be causing this and what we might do to prevent this from happening. 

 

We are also working with Esker to try to add a script that send a logoff command when the app is closed.

 

Thanks

 

Brian

 

Honored Contributor
Volker Halle
Posts: 5,206
Registered: ‎04-26-2004
Message 2 of 10 (669 Views)

Re: Runaway processes on disconnect

Brian,

 

what images are running in these 'looping' processes ? Use SHOW PROC/CONT/ID=<pid> against some of those.

 

What typically happens, is that an image is sitting on a prompt, reading from the terminal.   If the TELNET session gets terminated, there could very well be an IO error reading from the terminal. And the application might just re-try in case of an IO error when reading from the terminal. As fas as I remember, All-in-1 was some of those applications, which kept re-trying on failed terminal reads...

 

Volker.

Honored Contributor
Craig A Berry
Posts: 495
Registered: ‎05-06-2003
Message 3 of 10 (659 Views)

Re: Runaway processes on disconnect

Just to follow up on what Volker said, it's likely not the terminal emulator but the application the user is running, which may well have an exit handler that tries really hard to get confirmation from the user that they want to exit.  Such an exit handler really ought to confirm the terminal is still there, probably by calling $GETJPI with DVI$_AVL.

 

When I saw this problem it was in a discontinued third-party app with no prospect of getting the exit handler fixed.  So I wrote a program that periodically scanned all the interactive processes on the system and killed any with the terminal in an offline status.  Kind of a big hammer but it worked.

Honored Contributor
Steven Schweda
Posts: 9,096
Registered: ‎02-23-2005
Message 4 of 10 (650 Views)

Re: Runaway processes on disconnect

Trusted Contributor
John McL
Posts: 280
Registered: ‎02-24-2008
Message 5 of 10 (633 Views)

Re: Runaway processes on disconnect

Are the users running the same image via the terminal emulator or different images?  If it's the same image then could that image be at fault?

Trusted Contributor
John McL
Posts: 280
Registered: ‎02-24-2008
Message 6 of 10 (631 Views)

Re: Runaway processes on disconnect

Maybe I should have explained teh reason for my question...  Years ago I had a client with a big problem that had been there for months.  It was running a pay-TV application on VMS being accessed from PCs.  Every time the PC session was terminated - either just the session or the PC switched off - the VMS system would go to 100% CPU for about 10 minutes.

 

The reason was simple.  The exit handler in the pay-TV software wasn't working correctly and the database beneath it was rolling back after any abnormal termination of a connected VMS process.  After the pay-TV software was corrected the problem disappeared.

Trusted Contributor
abrsvc
Posts: 367
Registered: ‎06-08-2010
Message 7 of 10 (608 Views)

Re: Runaway processes on disconnect

I have resolved similar problems in the past as well. The easiest way to resolve this is to determine where the CPU time is being spent. As mentioned in a previous reply, either use the SHO PROC/CONT command or use ANALY/SYS to get PC values from the process (SDA> EXAM PC). Collect some PC values and post them here along with details about the OpenVMS version.

Using the SDA MAP command with the values obtained with a working process utilizing the same softare should provide clues.

Contact me directly if you need more assistance.

Dan
Occasional Visitor
PhilHaydicky
Posts: 1
Registered: ‎11-06-2013
Message 8 of 10 (510 Views)

Re: Runaway processes on disconnect

Dan - Thanks for the info. 

 

The tools you reference are not known to me, but I mucked about in VMS help and I think I was able to generate some data. 

 

I will take you up on your office for assistance via private email.

 

Thanks!

Phil

Trusted Contributor
EdgarZamora
Posts: 168
Registered: ‎10-17-2006
Message 9 of 10 (475 Views)

Re: Runaway processes on disconnect

We also use SmarTerm and we get these runaway processes once in a while.  It happens whenever the user X's out of SmarTerm without logging off.  I looked into this deeply back in 2007.  At first I looked at tcp/ip, and eventually came to the conclusion that somehow it was FMS that was the culprit.  Do you use FMS?  Anyway, the bottom line is we ended up writing a DCL program that monitors the system and automatically kills these runaway processes since we couldn't get FMS fixed.

 

Trusted Contributor
abrsvc
Posts: 367
Registered: ‎06-08-2010
Message 10 of 10 (465 Views)

Re: Runaway processes on disconnect

I have seen cases where incorrect calls to either FMS or SMG routines can cause this. In some cases, there is little left of the process to trace this. Thus, the requirement for examining the "run-away" process with SDA and tracking down the problem that way.

A solution is usually easy. It is the tracing of the exact problem that is tricky.

Dan
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