On Tue, Apr 02, 2019 at 04:54:00PM -0400, Mosleh Uddin wrote: > Hello, > > Could you give me some more insight into spawning my own sessiond? Sorry > I'm not completely clear on the topic. > Thank you for all your assistance.
Normally lttng-sessiond is treated as a "server/service/daemon" (think http server as apache) and is *normally* launched as a daemon (systemd/sysVinit) at boot time. Managing manually the lifetime of a lttng-sessiond process is done the same way as any other process. You can manage it via the command line (./lttng-sessiond), via a service manager (systemd/upstart etc.) or with a custom service manager (a python script/c etc.). You could spawn a lttng-sessiond from your application with the appropriate parameters set to isolate it if you need. LTTNG_HOME is an important one. The output directory also can be manipulated. See man lttng-sessiond for more details. You will need to manage the process or leave it to a system administrator and only active tracing when a sessiond is present for example. Cheers > > Regards, > Mosleh > > On Wed, Mar 27, 2019 at 1:52 PM Jonathan Rajotte-Julien < > jonathan.rajotte-jul...@efficios.com> wrote: > > > Hi Mosleh, > > > > On Wed, Mar 27, 2019 at 12:09:54PM -0400, Mosleh Uddin wrote: > > > Hello, > > > > > > Thank you for the quick response. I was able to use the documentation you > > > provided to start a session and get tracepoint list. I do have some > > > follow-up questions: > > > > > > 1) I needed to create a session daemon before executing my custom > > > application. In the API I did see functionality to see if a daemon is > > > active, however, it is possible to spawn a session daemon in my custom > > app? > > > > liblttng-ctl does not expose a lttng-sessiond spawning function since by > > definition it is a daemon executable (think apache,mysql etc.), you will > > have to > > use system/popen/exec.. to spawn the lttng-sessiond process etc. if you > > want to > > control its lifetime using your custom application. > > > > > > > > 2) I am able to get a list of active traces lttng can see in userspace, I > > > enable all the traces and start tracing. The traces however seem to not > > be > > > written anywhere on my filesystem. Do I have to specify a location? Or > > am I > > > missing something? My current flow is: > > > > Please refer to the create command. If outputting locally you will need to > > pass > > a "file://...." url to lttng_create_session. > > > > You can check on the result for each steps using "lttng list" and "lttng > > list > > <session_name>" as you go to troubleshot your setup script. > > > > While debugging you can also start the lttng-sessiond in verbose mode to > > understand what is going on. > > > > Also note that you could also use the lttng "load" api if the session you > > are > > trying to load is "static" and always the same. You would only need to > > ship an > > xml file with your application. > > > > Cheers > > > > > > > > - Creating a session > > > - Specifying the domain > > > - Creating a handle > > > - Creating a channel (with default attributes) > > > - Enabling the channel > > > - Enabling event (for all traces) > > > - Start tracing > > > > > > Thanks again for all the assistance. > > > > > > Regards, > > > Mosleh > > > > > > On Tue, Mar 26, 2019 at 11:29 AM Jonathan Rajotte-Julien < > > > jonathan.rajotte-jul...@efficios.com> wrote: > > > > > -- Jonathan Rajotte-Julien EfficiOS _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
