Hi Noam,

On 2016-08-17 06:25 AM, Noam Cohen wrote:
> Hello
> I installed lttng on my ubuntu, and tried the "getting Started".
>
> I ran the helloWorld, and then
> $ lttng list --userspace
> Error: Unable to list UST events: No session daemon is available
> Error: Command error
This looks like a normal error based on the absence of a session daemon.

> Waited a minute and retried, and now the output was as expected.

Is it possible you created a session in the mean time ?

The only command that should spawn a session daemon is "lttng create ... ".

Just to make sure this  is not simply because sessiond is not ready you 
can pass the "-b" option to lttng-sessiond to make sure that the command 
line return only when sessiond is ready.

> $ lttng list --userspace
> UST events:
> -------------
>
> PID: 17386 - Name: ./hello
>        lttng_ust_tracelog:TRACE_DEBUG (loglevel: TRACE_DEBUG (14)) (type:
> tracepoint)
>        < SNIP >
>        hello_world:my_first_tracepoint (loglevel: TRACE_DEBUG_LINE (13))
> (type: tracepoint)
>
> **Is it normal behavior?*
>
> Then,
> $ lttng create
> Session auto-20160817-132123 created.
> Traces will be written in /home/noam/lttng-traces/auto-20160817-132123
> noam at noam-nuc:~/tmp/lttng$ lttng enable-event --userspace
> hello_world:my_first_tracepoint
> Error: Event hello_world:my_first_tracepoint: UST create channel failed
> (channel channel0, session auto-20160817-132123)
This is clearly unexpected, logs should provide more information.
>
> How do I solve it?
> ---------------------
> system properties:
>
> noam at noam-nuc:~$ ps -ef | grep lttng
> noam     17410 17398  0 13:18 pts/3    00:00:00 lttng-sessiond -vvv

Since you passed the -vvv option could we see the log ?

> noam     17411 17410  0 13:18 pts/3    00:00:00 lttng-runas    -vvv
> noam     17442 17410  0 13:21 pts/3    00:00:00 lttng-consumerd  -u
> --consumerd-cmd-sock /home/noam/.lttng/ustconsumerd64/command
> --consumerd-err-sock /home/noam/.lttng/ustconsumerd64/error --group tracing
> noam     17444 17442  0 13:21 pts/3    00:00:00 lttng-runas      -u
> --consumerd-cmd-sock /home/noam/.lttng/ustconsumerd64/command
> --consumerd-err-sock /home/noam/.lttng/ustconsumerd64/error --group tracing
> noam     17480 17467  0 13:22 pts/7    00:00:00 grep --color=auto lttng
> noam at noam-nuc:~$ lsb_release -a
> No LSB modules are available.
> Distributor ID: Ubuntu
> Description: Ubuntu 16.04.1 LTS
> Release: 16.04
> Codename: xenial
>
>
> Installed lttng using:
> sudo apt-get install lttng-tools lttng-modules-dkms liblttng-ust-dev
>
>
> $ lttng --version
> lttng (LTTng Trace Control) 2.7.1 - Herbe à Détourne
>
>
>
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-- 
Jonathan R. Julien
Efficios