[Bug]: segfault on readout app at shutdown

Description

Description

A segfault occurs during application shutdown on np02-srv-003 running several dune daq versions, including v.5.6.0 as reported in op meetings (20, 27th of July).

The crash happens after the application has already logged a clean exit, so data integrity is not affected, but the signal 11 is noisy and may mask real issues.

Stack trace

2026-Aug-11 17:48:26,235 LOG [void dunedaq::opmonlib::OpMonManager::run(std::stop_token) at /tmp/root/spack-stage/spack-stage-opmonlib-v2.1.6-6kgxctp7miol4lqfk7k3xjkmzw4o7oun/spack-src/src/OpMonManager.cpp:75] Exiting the monitoring thread
2026-Aug-11 17:48:26,235 LOG [int main(int, char**) at /tmp/root/spack-stage/spack-stage-appfwk-v6.1.1-gbgr7tsjxulzolypyd6cbgrj4iqtnjr3/spack-src/apps/daq_application.cxx:79] Application main-np02-ops-pns.runp02srv003eth1 exiting.
2026-Aug-11 17:48:27,657 ERROR [static void ers::ErrorHandler::SignalHandler::action(int, siginfo_t*, void*) at /tmp/root/spack-stage/spack-stage-ers-v1.5.5-hkrj5g33t5yyjv7pyn74pdtcad4cex22/spack-src/src/ErrorHandler.cpp:90] Got signal 11 Segmentation fault (invalid memory reference)
        Parameters = 'name=Segmentation fault (invalid memory reference)' 'signum=11'
        Qualifiers = 'unknown'
        host = np02-srv-003
        user = np04daq (106200)
        process id = 3287102
        thread id = 3287102
        process wd = /nfs/sw/dunedaq/dunedaq-fddaq-v5.6.2-dev-ops-pns
        stack trace of the crashing thread:
          #0  /lib64/libc.so.6(free+0x1e) [0x7fcd652af91e]
          #1  /lib64/libc.so.6(+0x54db0) [0x7fcd65254db0]
          #2  /lib64/libc.so.6(free+0x1e) [0x7fcd652af91e]
          #3  /cvmfs/dunedaq.opensciencegrid.org/spack/releases/fddaq-v5.6.2-a9-1/spack-0.22.0/opt/spack/linux-almalinux9-x86_64/gcc-14.3.0/dpdklibs-v2.3.8-bzsbnyoww5v76u2sgerxsbebw77nzbbz/lib64/libdpdklibs.so(dunedaq::dpdklibs::IfaceWrapper::~IfaceWrapper()+0x6ed) [0x7fcd558a35fd]
          #4  daq_application(std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release_last_use_cold()+0xa) [0x4423da]
          #5  /cvmfs/dunedaq.opensciencegrid.org/spack/releases/fddaq-v5.6.2-a9-1/spack-0.22.0/opt/spack/linux-almalinux9-x86_64/gcc-14.3.0/dpdklibs-v2.3.8-bzsbnyoww5v76u2sgerxsbebw77nzbbz/lib64/libdpdklibs_DPDKReaderModule_duneDAQModule.so(dunedaq::dpdklibs::DPDKReaderModule::~DPDKReaderModule()+0x85) [0x7fcd55c3d465]
          #6  /cvmfs/dunedaq.opensciencegrid.org/spack/releases/fddaq-v5.6.2-a9-1/spack-0.22.0/opt/spack/linux-almalinux9-x86_64/gcc-14.3.0/dpdklibs-v2.3.8-bzsbnyoww5v76u2sgerxsbebw77nzbbz/lib64/libdpdklibs_DPDKReaderModule_duneDAQModule.so(std::_Sp_counted_ptr<dunedaq::dpdklibs::DPDKReaderModule*, (__gnu_cxx::_Lock_policy)2>::_M_dispose()+0x25) [0x7fcd55c7ece5]
          #7  daq_application(std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release_last_use_cold()+0xa) [0x4423da]
          #8  daq_application() [0x445d52]
          #9  daq_application(dunedaq::appfwk::Application::~Application()+0xee) [0x4586fe]
          #10 daq_application() [0x434a42]
          #11 /lib64/libc.so.6(+0x3feb0) [0x7fcd6523feb0]
          #12 /lib64/libc.so.6(__libc_start_main+0x80) [0x7fcd6523ff60]
          #13 daq_application() [0x435345]
~
"./log_np04daq_main-np02-ops-pns_runp02srv003eth1_2026-08-11-10-54-27.txt" [readonly] 1578L, 684606B

Steps to reproduce

the error will appear every now and then at shutdown.

Version and environment

dunedaq-fddaq-v5.6.0-dev

Impact

Small/Isolated

Anything else?

One can see a log here (also a printout below):
np02-srv-003:
/log//log_np04daq_main-np02-ops-pns_runp02srv003eth1_2026-08-11-10-54-27.txt

Start with the DPDKReaderModule and IfaceWrapper destructors named in the stack trace, then inspect the shutdown path through apps/daq_application.cxx and OpMonManager.cpp. Reproduce shutdown on the reported DUNE DAQ versions and use the provided signal-11 trace to isolate the invalid free. Done means the application exits without the intermittent segfault while preserving the clean shutdown behavior.