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
Regards,
Brian
On Thu, May 11, 2023 at 11:53 AM Brian Hutchinson <b.hutch...@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
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--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
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