Re: Autosave and IOC shutdown

[Ralph Lange <ralph.lange@gmx.de>]

Hi Tim,

(Sorry for sending to the wrong list. I had an email address entry 
labeled "Core-Talk" sending to tech-talk. Duh!)
Well played - as there's no distinct elaborate API for that stuff, the 
docs don't say too much.
There's a common pattern that is used in many places: global control 
variable plus a semaphore to wait for thread shutdown.
Look at dbScan.c or callback.c in BASE/src/ioc/db to get the idea.
Exit hooks registered using epicsAtExit() are called in reverse 
registration order. So, for a thread that uses services from Base: 
register late to be taken down early.
(Autosave configuration is done well before iocInit - probably too early 
for its exit hook registration. Might be better to do it from the thread.)
BTW: All this is basically present in 3.14, so not restricted to 3.15.

Thanks a lot,
~Ralph


On 23/09/2014 18:02, Mooney, Tim M. wrote:
> Hi Ralph,
>
> I'd like to fix this.  There are several threads spawned by various synApps modules.  I'll read the 3.15 docs and see how to comply.
>
> Tim Mooney (mooney@aps.anl.gov) (630)252-5417
> Software Services Group (www.aps.anl.gov)
> Advanced Photon Source, Argonne National Lab
>
>
> ________________________________________
> From: Ralph Lange [ralph.lange@gmx.de]
> Sent: Tuesday, September 23, 2014 10:34 AM
> To: Mooney, Tim M.
> Cc: EPICS Core-Talk
> Subject: Autosave and IOC shutdown
>
> Hi Tim,
>
> EPICS 3.15 is trying to make it easier for an IOC to cleanly shutdown.
> It add tests and better control over shutdown hooks.
> Autosave, on the other hand, starts a thread - running the
> save_restore() function - that is designed to never shut down.
>
> That seems like a clear conflict of interests, that shows as frequent
> error messages on shutdown:
>
> > A call to 'assert(dbLockIsInitialized)'
> >      by thread 'save_restore' failed in ../../../src/ioc/db/dbLock.c
> > line 255.
> > EPICS Release EPICS R3.15.0.1-DEV $$Date$$.
> > Local time is 2014-09-23 14:17:13.090976814 UTC
> > Please E-mail this message to the author or to tech-talk@aps.anl.gov
> > Calling epicsThreadSuspendSelf()
> (Autosave trying to use cleaned-up stuff in Base.)
>
> Do you have any thoughts on this?
>
> Cheers,
> ~Ralph