Not sure if this is the same problem since the attached stack trace is gone.
I have this very frequently with Ubuntu 17.10, It is the case both with the packaged version (0.9.0.13-1) and with the current master from git (version #a6666cf).
This appears to happen after a few samples. If I start arbtt-capture with a short sample duration, -r 10 perhaps, it will happen sooner. If I start it with -r 120 it will usually take longer.
I currently don't really know how to debug this any further, I tried starting it with gdb, but I have no debug binaries (and I couldn't easily figure out how to compile with debug traces). I'm very willing to help out further, but I will need some pointers on how to do so.
0.10.0.2 may have fixed segfaults for me. It's been running for a long time now. (it used to chrash after one minute pretty consistently before). Working with window titles including german umlauts, japanese characters and emoji.