Experimental Physics and
Industrial Control System

Michael Davidsaver <[email protected]> · Mon, 29 Oct 2018 11:30:32 -0700

On 10/29/18 11:11 AM, Kasemir, Kay wrote:
>>  Yes, something funny is happening.  Below is what 'pvinfo -d' on a machine
>> with two NICs should look like.  Note the "Broadcast address #1" which is
>> missing in your case.
>> From the ordering in your log it looks like somehow at attempt is being
>> made to send the GetField message before the TCP connection is created.
>> This smells like a race condition.
> 
> When I unset EPICS_PVA_ADDR_LIST and EPICS_PVA_AUTO_ADDR_LIST, I also get two addresses listed, but same end result: pvget works, pvinfo doesn't.

Ok, one mystery solved.

> $ pvget  training:ai1
> training:ai1 2018-10-29T14:09:16.942 2 MAJOR DEVICE LOLO 
> 
> $ pvinfo   training:ai1
> training:ai1 Error: channel destroyed

I've a suspicious that what you're seeing is a symptom of an exception
being thrown and swallowed.

Can you do a -debug build?

> cat <<EOF >>configure/CONFIG_SITE.local
> CROSS_COMPILER_TARGET_ARCHS+=\$(EPICS_HOST_ARCH)-debug
> EOF
> make

Then run in gdb:

> gdb --args ./bin/linux-x86_64-debug/pvinfo TST:iq

> b clientContextImpl.cpp:4679
> r
# this break should be reached on success or failure.  when it is reached.
> bt

https://github.com/epics-base/pvAccessCPP/blob/b28e33566b4a05cf54a6b3a8526112e5f420cec9/src/remoteClient/clientContextImpl.cpp#L4675

I see this happening on a TCP worker thread, but from the order of the log
messages I expect you will see something else.

> (gdb) bt
> #0  (anonymous namespace)::ChannelGetFieldRequestImpl::notify (this=0x555555849ff0, sts=..., 
>     field=std::shared_ptr (count 2, weak 1) 0x7fffe4000f90) at ../../src/remoteClient/clientContextImpl.cpp:4679
> #1  0x00007ffff779b07a in (anonymous namespace)::ChannelGetFieldRequestImpl::response (this=0x555555849ff0, transport=
>     std::shared_ptr (count 5, weak 1) 0x7fffe8000998, payloadBuffer=0x7fffe80009d8) at ../../src/remoteClient/clientContextImpl.cpp:4749
> #2  0x00007ffff779033f in (anonymous namespace)::ResponseRequestHandler::handleResponse (this=0x555555785a10, responseFrom=0x7fffe8000b4c, 
>     transport=std::shared_ptr (count 5, weak 1) 0x7fffe8000998, version=1 '\001', command=17 '\021', payloadSize=547, 
>     payloadBuffer=0x7fffe80009d8) at ../../src/remoteClient/clientContextImpl.cpp:2502
> #3  0x00007ffff77934cb in (anonymous namespace)::ClientResponseHandler::handleResponse (this=0x5555557853e0, responseFrom=0x7fffe8000b4c, 
>     transport=std::shared_ptr (count 5, weak 1) 0x7fffe8000998, version=1 '\001', command=17 '\021', payloadSize=547, 
>     payloadBuffer=0x7fffe80009d8) at ../../src/remoteClient/clientContextImpl.cpp:3012
> #4  0x00007ffff77747ba in epics::pvAccess::detail::BlockingTCPTransportCodec::processApplicationMessage (this=0x7fffe8000990)
>     at ../../src/remote/pv/codec.h:352
> #5  0x00007ffff776cdb7 in epics::pvAccess::detail::AbstractCodec::processReadNormal (this=0x7fffe8000990) at ../../src/remote/codec.cpp:224
> #6  0x00007ffff776c82a in epics::pvAccess::detail::AbstractCodec::processRead (this=0x7fffe8000990) at ../../src/remote/codec.cpp:128
> #7  0x00007ffff776fc71 in epics::pvAccess::detail::BlockingTCPTransportCodec::receiveThread (this=0x7fffe8000990)
>     at ../../src/remote/codec.cpp:1138
> #8  0x00007ffff777cee2 in epics::pvData::detail::MethRunner<epics::pvAccess::detail::BlockingTCPTransportCodec>::run (this=0x7fffe8005200)
>     at /home/mdavidsaver/work/epics/pv/pvData/include/pv/thread.h:56

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System