LTTng » LTTng-tools

There are a couple of weird behavior after the consumerD got killed via "kill" command.

Commit used when this test got carried out:
userspace-rcu : feb-08 fcf4348721903bed57027c7eb0ea13765895cd37
lttng-ust : feb-23 (20:11) 64493e4fa019e9bdfe0d9c6a4738c9552f250f35
lttng-tools : feb-24 (14:41) 6bf73bf53464ad309fcf7f02a4dc397d280b81f8
babeltrace : feb-23 (13:59) 305c65e5d7156ae7936f07ad93dd45ac318b4ce2

Here is the sceanrio:
1)_ lttng-sessiond -vvv &
2)_ Run the instrumented app
3)_ lttng create feb29_ses1 -o /tmp/tdlt/feb29_ses1
lttng enable-event the_tracepoint_name -u
lttng start
Note: There are a couple of printout, "TEST: lib_ring_buffer_reserve data_size..."
Those printf lines have been added by Mathieu to troubleshoot
Issue-24 yesterday.
4)_ ps -elf |grep ltt
5)_ kill <process ID of consumerD>
6)_ ps -elf |grep ltt
get: [lttng-consumerd] <defunct>
No new consumerD has been spawned
7)_ lttng stop
8)_ lttng start feb29_ses1 (start the session again with the hope that new
consummerD will be spawned)
Note: still no new consummerD

9)_ lttng stop
10)_ ls -lR /tmp/tdlt/feb29_ses1/ust/
get: all files with 0 size

11)_ lttng destroy

12)_ lttng create feb29_ses2 -o /tmp/tdlt/feb29_ses2 (test if new session is effected by the
fact that consumerD dies previously)

13)_ lttng enable-event tracepoint_name -s feb29_ses2 -u

Note: This process hang. Can not get the prompt back from the terminal (from where
              this command is entered).

<ctrl>+<z>
     bg

ps -elf |grep ltt
        get:  :
              [lttng-consumerd] <defunct>
              lttng enable-event ....           (enable-event is hanging)
              lttng-consumerd --quiet -u ....   (a new consumerD is spawned)
              :

14)_ lttng start
lttng stop
ls -lR /tmp/tdlt/feb29_ses2/ust/
get: no files being created for this session !

15)_ lttng enable-event a_new_tracepoint -s feb29_2 -u
Note: this one is also hanging !

<ctrl>+<z>
     bg
     ps -elf |grep ltt
        get:  :
              [lttng-consumerd] <defunct>
              lttng enable-event ....           (1st enable-event is hanging)
              lttng-consumerd --quiet -u ....   (previous consumerD is spawned)
              lttng enable-event ....           (2nd enable-event is hanging)
              lttng-consumerd --quiet -u ....   (a new consumerD is spawned)
              :

16)_ kill <process_id of sessiond>
ps -elf |grep ltt
get: :
[lttng-consumerd] <defunct>
lttng enable-event .... (1st enable-event is hanging)
lttng-consumerd --quiet -u .... (previous consumerD is spawned)
lttng enable-event .... (2nd enable-event is hanging)
lttng-consumerd --quiet -u .... (previous consumerD is spawned)
:

17)_ lttng-sessiond -vvv &

18)_ lttng list -u
Get: no apps has been registered !
That means the application that already ran (before the
consumerD is killed), can no longer see the new sessionD.

Therefore, no more tracing is possible !

Please, find enclosed the logfile for the above steps.