[lttng-dev] CentOS 7 and liburcu-common.so.3

[Thibault, Daniel]

I've grabbed recent source tarballs of the LTTng suite:

lttng-modules a606b6e 2.6.2-2 (2.6.0-rc1-101) 25 jun 2015 13:30:55
userspace-rcu b0a841b 0.8.7-13 (0.8.0-96) 8 Jul 2015 18:43:01
lttng-ust d8ecdf4 2.6.2.-20 (2.6.0-rc1-82)  8 Jul 2015 18:31:27
lttng-tools 7daee93 2.6.0-88 (2.6.0-rc1-241) 13 Jul 2015 15:21:01

and built them on two systems.  The first is a Ubuntu 15.04 vivid 3.19.0-16-generic x86_64, the second is a CentOS Linux release 7.1.1503 (Core) 3.10.0-229.el7 x86_64.
The first is also host to the second, which is a virtual machine.

Everything built and installed fine on both systems.  However, something happens on the CentOS that does not on the Ubuntu (both are virgin, with no tracing group yet, nor any automatic lttng-sessiond daemon):

$ su
# lttng create test_session
Spawning a session daemon
Warning: No tracing group detected
Session test_session created.
Traces will be written in /root/lttng-traces/ test_session-20150715-165116
# lttng enable-event -k -a

At this point, Ubuntu goes on with:

Warning: No tracing group detected
All Kernel events are enabled in channel channel0

While CentOS 7 does:

lttng-consumerd: error while loading shared libraries: liburcu-common.so.3: cannot open shared object file: No such file or directory
Error: Condition timed out.  The consumer thread was never ready. Killing it
Error: Fatal error spawning consumer control thread
Error: Events: Kernel consumer start failed (channel channel0, session test_session)
Error: Command error

At this point the system monitor shows lttng-sessiond and lttng-consumerd still up (so I guess the killing failed too).  If I then kill lttng-sessiond:

# kill 3425
# PERROR - 17:22:17.123456 [3425/3425]: kernel consumer err_sock close: Bad file descriptor (in close_consumer_sockets() at main.c:529)

What's strange is that liburcu-common.so.3 is present in the CentOS system, in the same place, and is found in the same way by 'whereis'.  Any clues?

Daniel U. Thibault, M.Sc.²

Scientifique de la défense, 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

Defence 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