(gdb) bt full
#0  0x0000000000000000 in ?? ()
No symbol table info available.
#1  0x000003e9be16c260 in _dt_sigsegv_handler () from /usr/local/lib/libdarktable.so
No symbol table info available.
#2  <signal handler called>
No symbol table info available.
#3  _rthread_mutex_timedlock (mutexp=<optimized out>, trywait=0, abs=0x0, timed=0) at /usr/src/lib/libc/thread/rthread_mutex.c:166
        error = <error reading variable error (Cannot access memory at address 0x0)>
        self = 0x3ea94b46c40
        mutex = 0x3ea45930002
        i = <optimized out>
        lock = <optimized out>
#4  0x000003e9be1a040e in dt_dev_pixelpipe_cleanup_nodes () from /usr/local/lib/libdarktable.so
No symbol table info available.
#5  0x000003e9be1a039d in dt_dev_pixelpipe_cleanup () from /usr/local/lib/libdarktable.so
No symbol table info available.
#6  0x000003e9be14d05a in dt_imageio_export_with_flags () from /usr/local/lib/libdarktable.so
No symbol table info available.
#7  0x000003e9be162dc1 in _init_8 () from /usr/local/lib/libdarktable.so
No symbol table info available.
#8  0x000003e9be1622a7 in dt_mipmap_cache_get_with_caller () from /usr/local/lib/libdarktable.so
No symbol table info available.
#9  0x000003e9be1883ba in dt_image_load_job_run () from /usr/local/lib/libdarktable.so
No symbol table info available.
#10 0x000003e9be1821f9 in dt_control_job_execute () from /usr/local/lib/libdarktable.so
No symbol table info available.
#11 0x000003e9be182a0d in dt_control_work () from /usr/local/lib/libdarktable.so
No symbol table info available.
#12 0x000003e9cb9aec0e in _rthread_start (v=0x3e9fb88d615) at /usr/src/lib/librthread/rthread.c:96
        thread = 0x3e9fb88d615
        retval = <optimized out>
#13 0x000003e9fb74125b in __tfork_thread () at /usr/src/lib/libc/arch/amd64/sys/tfork_thread.S:75
No locals.
#14 0x0000000000000000 in ?? ()
No symbol table info available.