Interesting.  Rebuilt the entire LTTng set with the stable-1.8 releases (stable-0.9 for userspace-rcu) and I see the same behaviour:
When I hit ctrl-c in the daemon's shell, it doesn't respond and the CPU usage goes crazy (~90%).  Can't sudo kill it (or lttng-runas) either.

What's strange is that if instead of:

$ lttng-sessiond -vvv 2>&1 | tee lttng-sessiond.2.log

I do:

$ lttng-sessiond 2>&1 | tee lttng-sessiond.3.log

Then ctrl-c terminates lttng-sessiond normally.

Using just the first level of verbosity:

$ lttng-sessiond -v 2>&1 | tee lttng-sessiond.4.log

also misbehaves.  Somehow -v is responsible?

At this point, should I open a bug?

Daniel U. Thibault, M.Sc.²

Informaticien scientifique, CME-PSC, Centre de recherches de Valcartier
Recherche et développement pour la défense Canada / Gouvernement du Canada
daniel.thibault at drdc-rddc.gc.ca / Tél: 418-844-4000x4245 Téléc: 418-844-4538
daniel.thibault at forces.gc.ca / Tél: 418-844-4000x4245 Téléc: 418-844-4538

Computer Scientist, MCCS-SPC, Valcartier Research Centre 
Defence Research and Development Canada / Government of Canada
daniel.thibault at drdc-rddc.gc.ca / Tel: 418-844-4000x4245 Fax: 418-844-4538
daniel.thibault at forces.gc.ca / Tel: 418-844-4000x4245 Fax: 418-844-4538

DRDC is an agency of the Department of National Defence / RDDC est une agence du ministère de la Défense nationale