Re: deadlock in pcas 3.14.12.6-rc1

[Bruce Hill <bhill@slac.stanford.edu>]

Hi Xiaoqiang,
Thanks, I was able to reproduce the bug using your suggestions.
I've submitted a proposed fix on launchpad.   Please let me know if you
have a chance to try it.    My version ran all day today w/o crashing.
https://code.launchpad.net/~bhill/epics-base/pcas-deadlock-fix-3.14/+merge/312638 
<https://code.launchpad.net/%7Ebhill/epics-base/pcas-deadlock-fix-3.14/+merge/312638>

Cheers,
- Bruce


On 12/6/2016 1:38 AM, Wang Xiaoqiang (PSI) wrote:
> Hi Bruce,
>
> I replied you here https://github.com/paulscherrerinstitute/pcaspy/issues/29#issuecomment-265103000
>
> I carried out the described test procedure on a SL6 64bit Linux PC. The problem appears definitely in a few seconds.
>
> Best
> Xiaoqiang
>
> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Bruce Hill
> Sent: Dienstag, 6. Dezember 2016 04:15
> To: tech-talk@aps.anl.gov
> Subject: Re: deadlock in pcas 3.14.12.6-rc1
>
> Hi Xiaoqiang,
> Do you have a pcaspy example that I can run to reproduce this?
>
> I'm running pcaspy 0.6.2 currently, but could also build from a github branch if available.
>
> Thanks,
> - Bruce
>
>
> On 11/10/2016 08:59 AM, Wang Xiaoqiang (PSI) wrote:
> > Hi,
> >
> > I am testing the support of dynamic array in the recent base 3.14.12.6-rc1.
> > Using a normal pcaspy application, which updates ~15 Hz. It repeatedly gets into a deadlock state.
> >
> > The analysis has been put up here
> > https://github.com/paulscherrerinstitute/pcaspy/issues/29
> >
> > The solution could be reversing the lock order during
> > casEventSys::process. But it does not seem to be easy, because the chain of calls involved.
> >
> > Best
> > Xiaoqiang
> --
> Bruce Hill
> Member Technical Staff
> SLAC National Accelerator Lab
> 2575 Sand Hill Road M/S 10
> Menlo Park, CA  94025