[lttng-dev] LTTNG LIB UST Crash

Wed Sep 6 11:31:46 EDT 2023

Hi Lakshmi,

On 2023-09-06 06:02, Lakshmi Deverkonda via lttng-dev wrote:
> Thanks for the reply. Issue is fixed after loading the tracing helpers.
> 
> I have one query wrt to logging wrt lttng on python3 application. Is 
> there any way I can avoid the file logging and only trace via lttng ?
> 

In the example python application at 
https://lttng.org/docs/v2.13/#doc-python-application the log messages 
are not written to disk or to stderr.

I lack the details of your application to give you a more precise answer.

Hope this helps,
kienan

> Regards,
> Lakshmi
> 
> 
> ------------------------------------------------------------------------
> *From:* Kienan Stewart <kstewart at efficios.com>
> *Sent:* 05 September 2023 21:20
> *To:* Lakshmi Deverkonda <laksd at nvidia.com>
> *Subject:* Re: [lttng-dev] LTTNG LIB UST Crash
> External email: Use caution opening links or attachments
> 
> 
> Hi Lakshmi,
> 
> could you please provide us with the system details and version
> information for LTTng tools and UST?
> 
> The bug reporting guidelines which cover the type of information
> required to respond adequately questions can be found here:
> https://lttng.org/community/#bug-reporting-guidelines <https://lttng.org/community/#bug-reporting-guidelines>
> 
> Given that you are instrumenting a user space application, do you have a
> minimal reproducer of the crash including the details of how the
> application is invoked that you would be able to share?
> 
> Some types of user space applications required tracing helpers loaded
> via LD_PRELOAD. More information can be found here
> https://lttng.org/docs/v2.13/#doc-prebuilt-ust-helpers <https://lttng.org/docs/v2.13/#doc-prebuilt-ust-helpers>
> 
> If you're unable to share code or other log files due to company policy,
> or require responses within a guaranteed time frame, EfficiOS offers
> commercial support services: 
> https://www.efficios.com/services/ <https://www.efficios.com/services/>
> 
> thanks,
> kienan
> 
> p.s. Sorry for forgetting to CC you in my earlier reply to the list!
> 
> On 2023-09-05 02:30, Lakshmi Deverkonda via lttng-dev wrote:
>> Hi All,
>>
>> I am observing lttng crash while trying to interface LTTNG for one of my
>> python3 application.
>> I just tried the following things,
>>
>> Added "import lttngust " in the code.
>>
>> # lttng create clagd
>> Session clagd created.
>> Traces will be written in /root/lttng-traces/clagd-20230905-062210
>>
>> # lttng enable-event --python clagd
>> #lttng start
>>
>> #service clagd start
>> *
>> *
>> *cumulus-core: Running cl-support for core files
>> "clagd-ust.95410.1693895062.core"*
>>
>> #0  0x00007f134fb938eb in raise () from /lib/x86_64-linux-gnu/libc.so.6
>> #1  0x00007f134fb7e535 in abort () from /lib/x86_64-linux-gnu/libc.so.6
>> #2  0x00007f134fb7e40f in ?? () from /lib/x86_64-linux-gnu/libc.so.6
>> #3  0x00007f134fb8c1a2 in __assert_fail () from
>> /lib/x86_64-linux-gnu/libc.so.6
>> #4  0x00007f134f1a9677 in lttng_ust_add_fd_to_tracker () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #5  0x00007f134f1bdcf4 in lttng_ust_elf_create () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #6  0x00007f134f1bf8de in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #7  0x00007f134fc8f957 in dl_iterate_phdr () from
>> /lib/x86_64-linux-gnu/libc.so.6
>> #8  0x00007f134f1bff6b in lttng_ust_dl_update () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #9  0x00007f134f1c061a in do_lttng_ust_statedump () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #10 0x00007f134f1b5ca9 in lttng_handle_pending_statedump () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #11 0x00007f134f1ab6d1 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #12 0x00007f134f1ad7eb in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #13 0x00007f134ff0dfa3 in start_thread () from
>> /lib/x86_64-linux-gnu/libpthread.so.0
>> #14 0x00007f134fc5506f in clone () from /lib/x86_64-linux-gnu/libc.so.6
>>
>>
>> When I stop the lttng session, I see another core
>>
>> #0  0x00007fad951988eb in raise () from /lib/x86_64-linux-gnu/libc.so.6
>> [Current thread is 1 (Thread 0x7fad9331f700 (LWP 2221103))]
>> (gdb) bt
>> #0  0x00007fad951988eb in raise () from /lib/x86_64-linux-gnu/libc.so.6
>> #1  0x00007fad95183535 in abort () from /lib/x86_64-linux-gnu/libc.so.6
>> #2  0x00007fad9518340f in ?? () from /lib/x86_64-linux-gnu/libc.so.6
>> #3  0x00007fad951911a2 in __assert_fail () from
>> /lib/x86_64-linux-gnu/libc.so.6
>> #4  0x00007fad947e8d9f in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #5  0x00007fad947e98e3 in shm_object_table_destroy () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #6  0x00007fad947e4d9a in channel_destroy () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #7  0x00007fad947ba6b5 in lttng_session_destroy () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #8  0x00007fad947b47c6 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #9  0x00007fad947b4bac in lttng_ust_objd_unref () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #10 0x00007fad947b4bac in lttng_ust_objd_unref () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #11 0x00007fad947b4bac in lttng_ust_objd_unref () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #12 0x00007fad947b5304 in lttng_ust_objd_table_owner_cleanup () from
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #13 0x00007fad947b2b75 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0
>> #14 0x00007fad95512fa3 in start_thread () from
>> /lib/x86_64-linux-gnu/libpthread.so.0
>> #15 0x00007fad9525a06f in clone () from /lib/x86_64-linux-gnu/libc.so.6
>>
>>
>> Can you please help here if I'm missing something. This is a critical
>> task item for us but are currently stuck with multiple lttng crashes.
>>
>> Regards,
>> Lakshmi
>>
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> 
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