[lttng-dev] I'm still getting empty ust traces using tracef

[Brian Hutchinson]

Hi Mathieu,


On Thu, May 11, 2023 at 2:12 PM Mathieu Desnoyers
<mathieu.desnoyers at efficios.com> wrote:
>
> On 2023-05-11 12:36, Brian Hutchinson via lttng-dev wrote:
> > ... more background.  I've always used ltt in the kernel so I don't
> > have much experience with the user side of it and especially
> > multi-threaded, multi-core so I'm probably missing some fundamental
> > concepts that I need to understand.
>
> Which are the exact versions of LTTng-UST and LTTng-Tools you are using
> now ? (2.13.N or which git commit ?)
>
> Thanks,
>
> Mathieu

Built into my rootfs with Yocto:

-rw-r--r-- 4 hutch hutch   977252 May  2 15:32 lttng-tools-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch 11466008 May  2 15:33
lttng-tools-dbg-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch    49104 May  2 15:32
lttng-tools-dev-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch    87452 May  2 15:32
lttng-tools-doc-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch  1602356 May  2 15:32
lttng-tools-ptest-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch   867164 May  2 15:32
lttng-tools-src-2.13.9-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch   219952 May  2 15:31 lttng-ust-2.13.5-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch     9248 May  2 15:31
lttng-ust-bin-2.13.5-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch   970248 May  2 15:31
lttng-ust-dbg-2.13.5-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch    49132 May  2 15:31
lttng-ust-dev-2.13.5-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch    39864 May  2 15:31
lttng-ust-doc-2.13.5-r0.aarch64.rpm
-rw-r--r-- 4 hutch hutch   258392 May  2 15:31
lttng-ust-src-2.13.5-r0.aarch64.rpm

Regards,

Brian

>
> >
> > Regards,
> >
> > Brian
> >
> > On Thu, May 11, 2023 at 11:53 AM Brian Hutchinson <b.hutchman at gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> I posted a while ago (thread - Using lttng 2.11 and UST doesn't appear
> >> to work - getting empty trace files) about this problem I'm having
> >> with getting empty trace logs.
> >>
> >> I've since upgraded to lttng v2.13 and while I can do a simple hello
> >> world program with tracef and get events in the log files, my more
> >> complicated large multi-threaded app I'm trying to debug is still
> >> getting empty log file traces.
> >>
> >> I can list the user space events in my app.
> >>
> >> Next I do:
> >>
> >> lttng enable-event --userspace 'lttng_ust_tracef:*'
> >>
> >> ... to enable the events, start lttng, start my app, .... and I get a
> >> trace directory structure that's empty.
> >>
> >> I feel like I've read every thread in the archives about people having
> >> the same problem.
> >>
> >> I did try using LD_PRELOAD with various libs thinking that was the
> >> problem but so far I'm still getting empty traces.
> >>
> >> So far I've tried:
> >>
> >> LD_PRELOAD=liblttng-ust-libc-wrapper.so.1:liblttng-ust-pthread-wrapper.so.1:liblttng-ust-dl.so.1:liblttng-ust-fork.so.1:liblttng-ust-fd.so.1
> >> /usr/local/bin/my_app
> >>
> >> I guess one question I have is how do I determine which "helper libs"
> >> I need to preload?
> >>
> >> The application I'm working on is made up of a bunch of smaller static
> >> libs linked together into one big executable and that is linked with
> >> -llttng-ust and -ldl.
> >>
> >> I'm pretty stuck at the moment.  Anyone have any wisdom on what I
> >> might be doing wrong or how I can tell why I'm not getting events in
> >> the logs?
> >>
> >> Thanks,
> >>
> >> Brian
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com
>