The first thing you should do to provide more information is to run the lttng-sessiond by itself, with full logging activated.
To do this, as the same user you were running lttng, just run lttng-sessiond -vvv and then run your lttng commands as usual. (Make sure you do not have other lttng-sessiond running) With that you will see the full output of the session daemon. We might see some errors there. On 2012-01-04 12:28, Sébastien Barthélémy wrote: > Hello all, > > I'd like to report that sometimes lttng freezes while creating a session. > > This is kind of sporadic, but happens almost half the times on this > target. I have not seen this behaviour on two other targets. It might > well be a cross build trick or so. > > I straced a session, here is the interesting excerpt (full strace attached) > > $ killall lttng-sessiond > $ strace lttng create > ... > write(2, "Spawning a session daemon\n", 26Spawning a session daemon > ) = 26 > clone(child_stack=0, > flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, > child_tidptr=0xb7ef3728) = 4044 > --- SIGCHLD (Child exited) @ 0 (0) --- > sigreturn() = ? (mask now []) > pause( > > I'm not sure what happens. It seems to me that > > 1) lttng-sessiond sends SIGCHLD, > 2) lttng catches the signal > 3) lttng is still locked in pause() > > But I may be misinterpreting all this. > > Moreover, having had a quick look at the lttng source code, I noticed > it calls lttng-sessiond without the --daemonize option. I do not > understand how the latter survives the former in such a case. > > Any idea on how I could further analyse this? > > Cheers > > -- Sebastien Barthelemy > > > _______________________________________________ > lttng-dev mailing list > [email protected] > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
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