Tor crashes after numerous failed name resolutions.
If a tor exit node is unable to contact a DNS server, after numerous failed name resolution attempts, tor will crash.
gdb(1) seems to always point to the FreeBSD pthread library when asking "where" post-mortem. Apologies for not having the exact output, as I have fixed the issue and no longer have the core (and would like to not break it again).
However, should you be confirming this, the easiest way to replicate this is by setting up a tor exit node with a relatively unrestricted exit policy (the default should do). Make sure that tor does not query a valid nameserver by modifying your /etc/resolv.conf (easiest way to do this without breaking DNS on the host machine is to run tor in a chroot(8) or jail(8) environment) to point to an invalid nameserver. After a few hours (maybe less on high band- width nodes) tor will crash, dropping it's core.
[Automatically added by flyspray2trac: Operating System: BSD]