[lttng-dev] Trace Compass in live session

[Jonathan Rajotte-Julien]

Hi Thierry,

Glad you got the base setup working.

Please reply to the other thread indicating what was necessary to make it work on your end. This might be useful for other people in the future.

Now my question is what is the end goal of using the live streaming mode. Is it really necessary?
What are you trying to achieve overall? 
Are you trying to debug a certain scenario on you platform that can be reproduced easily?
Are you simply checking out how LTTng works?

Please provide more context so we can help you.

See more inline.

----- Original Message -----
> From: "BADEUIL Thierry" <thierry.badeuil at thalesgroup.com>
> To: "lttng-dev" <lttng-dev at lists.lttng.org>
> Sent: Tuesday, June 12, 2018 12:29:22 PM
> Subject: [lttng-dev] Trace Compass in live session

> Dear all,
> 
> 
> 
> I have difficulties to use Babeltrace in live session and I would like to
> use Trace Compass.

What problem are you hitting?

TraceCompass does not support the live protocol. See [1] [2] for why.

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=486728
[2] https://git.eclipse.org/r/#/c/69285/

> 
> 
> 
> My target activated LTTng with :
> 
> -          Lttng create test –live –set-url:’net://192.168.0.1:5342:5343’

This should be: lttng create test --set-url="net://192.168.0.1:5342:5343" --live

> 
> -          Lttng enable-event sched_switch
> 
> -          Lttng start
> 
> 
> 
> My host (@192.168.0.1) activated LTTng with :
> 
> -          Lttng-relayd –vv

Since this seems to be working you can drop the verbose options (-vvv).

> 
> 
> 
> Everything seems to be OK because my host received bytes from my target
> during 1 minute.

Does the event timestamps show a 1 minute difference on the console? Note that even if you see events outputted to the console during 
1 minute does not necessarily means that a full minute of "events" is present since there might be latency between a "lttng stop" and a 
complete live reception. It take more time to serialize (in time) events than to produce them.

> 
> I would like to see the traces in ~/lttng-traces with TraceCompass and I can
> only watch the first second of my recording. It is impossible to see after
> (I did a lot of refresh…).

Is your session stopped/destroyed?

If it is the case, you should be able to read the complete trace from TraceCompass or LTTng Scope. Could you upload the trace (make sure there is no private data)?

Cheers