Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Mon, 25 Sep 2006 16:17:28 -0600

The CAJ <=> CA server incompatibility is being tracked as mantis bug
tracking entry 268 (against IOC core's CA server - in EPICS base).

Jeff

> -----Original Message-----
> From: Kay-Uwe Kasemir [mailto:[email protected]]
> Sent: Monday, September 25, 2006 12:15 PM
> To: tech talk
> Subject: Re: Experience with CAJ
> 
> On Sep 25, 2006, at 13:43 , Christopher Larrieu wrote:
> 
> > Does anyone have experience using Cosylab's java channel access
> > (CAJ) in a
> > real-world, production system?  I'm curious about using it in lieu
> > of JCA.
> 
> Hi Chris:
> 
> Are you the same Chris who used to be on the 'other' coast of the US?
> 
> At the SNS, we had problems with the pure java CA client lib when
> it comes to IOCs that use CA security.
> The CA server on the IOCs would enter a state where it's hung.
> New CA connections would create new client threads, but each new
> thread hangs waiting for some semaphore inside the access security
> library's asAddClient() routine.
> Try searching previous tech talk messages:
> http://www.aps.anl.gov/epics/tech-talk/2006/msg00503.php,
> and look around April 25, 2006 for messages from Jeff and me.
> 
> The symptom: No new CA connections, and a 'caget some_PV' will issue
> the 'timeout' error messag after about 1 second
> (as common for missing PVs), but hang for another 29 seconds before
> exiting
> (symptomatic for this error where the new client thread is created
> but then hangs).
> 
> Since this is very bad for operational IOCs, the only remedy being a
> reboot,
> we quit using CAJ for now.
> 
> The problem is probably caused by CAJ sending user/host information
> in the 'wrong'
> order or at a 'bad' time, but with CA it's of course a bit difficult
> to determine
> what's a 'correct' message or the 'right' time ;-).
> At one time we caught the error with a version of EPICS base that was
> patched
> to allow a 'semShow' on the access security semaphore. I think it showed
> that another CA task held the semaphore, but I can't find the detail any
> longer. Maybe Jeff remembers, I'm pretty sure I emailed him the results.
> 
> I also saw occasional messages on the IOC
>    CAS: request from someIP:port => "bad resource ID"
> which only occurred when using CAJ.
> 
> So while I think CAJ is terrific, I would only use it through a gateway
> until these kinks are worked out.
> 
> With the JNI-based CA client library for Java, there are also issues
> that Tom Pelaia at the SNS and Matej at Cosylab are currently
> investigating:
> As far as I understand, the JNI code includes a list for the incoming
> monitors.
> If the java client code doesn't digest them fast enough, that list
> grows ad infimum,
> instead of engaging the CA flow control.
> We first thought it's a memory leak, since the app keeps growing.
> It's not, just a list that grows, but nonetheless fatal.
> 
> -Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System