6.2 Generating backtrace

There are several ways to achieve that, the most common way is to leave core dumps and then extract a backtrace from it. This doesn't affect any server operation, you just need to make sure the OS is configured to generate them.

     $ ulimit -c unlimited # enable unlimited core dump size
     ...
     $ gdb $(which knotd) core.<KNOT_PID>   # start gdb on a core dump
     (gdb) thread apply all bt    # extract backtrace from all threads
     (gdb) q

If the error is repeatable, you can run the binary in a gdb debugger or attach the debugger to the running process. The backtrace from a running process is generally useful when debugging problems like stuck process and similar.

     $ knotc -c knot.conf start
     $ sudo gdb --pid <KNOT_PID>
     (gdb) continue
     ...
     (gdb) thread apply all bt
     (gdb) q