(gdb) bt
#0  0x00007ffff57857bb in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007ffff5770535 in __GI_abort () at abort.c:79
#2  0x00007ffff5b8c983 in __gnu_cxx::__verbose_terminate_handler() () at ../../../../src/libstdc++-v3/libsupc++/vterminate.cc:95
#3  0x00007ffff5b928c6 in __cxxabiv1::__terminate(void (*)()) (handler=<optimized out>) at ../../../../src/libstdc++-v3/libsupc++/eh_terminate.cc:47
#4  0x00007ffff5b92901 in std::terminate() () at ../../../../src/libstdc++-v3/libsupc++/eh_terminate.cc:57
#5  0x00007ffff5b9363f in __cxxabiv1::__cxa_pure_virtual() () at ../../../../src/libstdc++-v3/libsupc++/pure.cc:50
#6  0x00007ffff634ea70 in OscilloscopeChannel::Disable() (this=0x555556794f50) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/OscilloscopeChannel.cpp:174
#7  0x00007ffff634e8d4 in OscilloscopeChannel::Release() (this=0x555556794f50) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/OscilloscopeChannel.cpp:140
#8  0x00007ffff632bd02 in FlowGraphNode::~FlowGraphNode() (this=0x55555927d5e0, __in_chrg=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/FlowGraphNode.cpp:58
#9  0x00007ffff632e8b2 in Trigger::~Trigger() (this=0x55555927d5e0, __in_chrg=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/Trigger.cpp:46
#10 0x00007ffff6334564 in EdgeTrigger::~EdgeTrigger() (this=0x55555927d5e0, __in_chrg=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/EdgeTrigger.cpp:55
#11 0x00007ffff6334580 in EdgeTrigger::~EdgeTrigger() (this=0x55555927d5e0, __in_chrg=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/EdgeTrigger.cpp:58
#12 0x00007ffff633c956 in Oscilloscope::~Oscilloscope() (this=0x555556402cc0, __vtt_parm=0x7ffff647be48 <VTT for LeCroyOscilloscope+16>, __in_chrg=<optimized out>)
    at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/Oscilloscope.cpp:63
#13 0x00007ffff63503f1 in SCPIOscilloscope::~SCPIOscilloscope() (this=0x555556402cc0, __vtt_parm=0x7ffff647be40 <VTT for LeCroyOscilloscope+8>, __in_chrg=<optimized out>)
    at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/SCPIOscilloscope.cpp:43
#14 0x00007ffff6378ec3 in LeCroyOscilloscope::~LeCroyOscilloscope() (this=0x555556402cc0, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/LeCroyOscilloscope.cpp:885
#15 0x00007ffff6378f20 in LeCroyOscilloscope::~LeCroyOscilloscope() (this=0x555556402cc0, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at /ceph/fast/home/azonenberg/code/scopehal-apps/lib/scopehal/LeCroyOscilloscope.cpp:888
#16 0x000055555579ab16 in ScopeApp::ShutDownSession() (this=0x5555558a9a30) at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/ScopeApp.cpp:114
#17 0x000055555573f0fd in OscilloscopeWindow::CloseSession() (this=0x55555633f7c0) at /ceph/fast/home/azonenberg/code/scopehal-apps/src/glscopeclient/OscilloscopeWindow.cpp:635