Re: ca_repeater bug (probably observable only on RTEMS)

[Kate Feng <feng1@bnl.gov>]

Jeff Hill wrote:

> This code was written a long time ago. With R3.13 it executes as a thread
> only on vxWorks, and on vxWorks exit() causes only the thread to exit.
>
> Of course, now with R3.14 the code runs also on other OS where exit() may
> have a different behavior. In particular, on Linux, Solaris, HPUX, Windows,
> etc exit() will cause the process to exit, but that behavior should not be
> observed because osiSpawnDetachedProcess() is implemented on these systems,
> and therefore the CA repeater always runs in an independent detached
> process. It is not running as a thread in the IOC as is the case with
> vxWorks.
>
> That leaves RTEMS. The osiSpawnDetachedProcess() function is not (probably
> cant be) implemented on RTEMS and so you will end up with the CA repeater
> running as an RTEMS thread. However, perhaps on RTEMS exit() causes the
> RTEMS OS to shut down? That might be a more appropriate implementation of
> exit() compared to vxWorks.
>

However,  the IOC  did not exit and  cause RTEMS shut down if I  add
one clock tick of  delay after motor initialzation.  It works fine for  the
workaround.    Assuming the answers to the above questions are yes,
perhaps EPICS  had  enough intelligence to  undo the OS exit() if given
one clock tick of delay to  figure out ?   Is this why the workaround works ?

Thanks,
Kate


>
> What symptoms did you observe that led to finding this fix? I just read that
> Kate observed a hang (which I assume means that RTEMS shut down).
>
> Thanks for bringing this to our attention.
>
> Jeff
>
> > -----Original Message-----
> > From: Till Straumann [mailto:strauman@slac.stanford.edu]
> > Sent: Wednesday, September 15, 2004 5:34 PM
> > To: tech-talk@aps.anl.gov
> > Subject: ca_repeater bug
> >
> > Folks.
> >
> > the caRepeater thread calls 'exit()' which is not really
> > what you want to do from the ca server (I guess)
> >
> > -- T.