Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Fri, 1 May 2020 14:08:26 -0700

On 5/1/20 3:08 AM, Jonas Nilsson via Tech-talk wrote:
> Hello,
> 
> For lack of a better idea on where to report a bug in EPICS base, here it is;

In this case the pvAccessCPP module has both pvac::ClientProvider and the "ca" provider.

https://github.com/epics-base/pvAccessCPP

> Calling the destructor on more than one instance of a pvac::ClientProvider which has been constructed with a provider name of "ca" (channel access) causes (what appears to be) a deadlock. Using "pva" (pvAccess) does not appear to trigger this deadlock. I have attached a screenshot of where the deadlock appears to be located (from pausing the application when running it under a debugger).

Text is much preferred to screen shots.

Can you identify and provide a stack trace from the other thread(s) participating in this deadlock?
If not, please attach stack traces from all threads.

> The code that causes the triggers the deadlock can be found here: https://github.com/ess-dmsc/forward-epics-to-kafka/blob/a75fab2a7343906c147722825a258332fc2126e7/src/EpicsClient/EpicsClientMonitorImpl.h

I'm confused by the presence of both pvac::ClientProvider and the lower level epics::pvAccess::ChannelProvider.
The idea of the first is to avoid the complexities of the second.

> In this piece of code, the version of EPICS base used is 7.0.3.1. I believe I had a the same issue when testing with  earlier versions of EPICS7 a few months back as well. 
> 
> /Jonas
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System