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Thanks for replying.</div>
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Basically in our python3 application, we already have a logger which will redirect the logs to a log file. By default, only info logs gets logged unless user explicitly turns on debug logging via cli. </div>
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For LTTNG Tracing, we would want to log all the events that is both info/debugs. </div>
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>>Do you think there would be any overhead on the application?</div>
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>> I cannot use the existing logger which does a file logging so for lttng only I have created just a new logger without any handler. Should this be fine?</div>
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>>Also, I see the default channel created for the python logging in lttng "lttng_python_channel" . From the documentation, I see that we cannot create another channel for python logging. </div>
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I would want to modify some of the attribute for the default channel such as making event-loss-mode as "overwrite" and increasing the trace_file_count. How can I do it ? This is one of the necessary requirement for our application. Can you please guide on this
?</div>
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Regards,</div>
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Lakshmi</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Kienan Stewart <kstewart@efficios.com><br>
<b>Sent:</b> 06 September 2023 21:01<br>
<b>To:</b> lttng-dev@lists.lttng.org <lttng-dev@lists.lttng.org>; Lakshmi Deverkonda <laksd@nvidia.com><br>
<b>Subject:</b> Re: [lttng-dev] LTTNG LIB UST Crash</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">External email: Use caution opening links or attachments<br>
<br>
<br>
Hi Lakshmi,<br>
<br>
On 2023-09-06 06:02, Lakshmi Deverkonda via lttng-dev wrote:<br>
> Thanks for the reply. Issue is fixed after loading the tracing helpers.<br>
><br>
> I have one query wrt to logging wrt lttng on python3 application. Is<br>
> there any way I can avoid the file logging and only trace via lttng ?<br>
><br>
<br>
In the example python application at<br>
<a href="https://lttng.org/docs/v2.13/#doc-python-application">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flttng.org%2Fdocs%2Fv2.13%2F%23doc-python-application&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141743499%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=HMryNCihtLBKA49TWfsxp4%2FkzkFJhZrlyocoAsR7w78%3D&reserved=0</a>
the log messages<br>
are not written to disk or to stderr.<br>
<br>
I lack the details of your application to give you a more precise answer.<br>
<br>
Hope this helps,<br>
kienan<br>
<br>
> Regards,<br>
> Lakshmi<br>
><br>
><br>
> ------------------------------------------------------------------------<br>
> *From:* Kienan Stewart <kstewart@efficios.com><br>
> *Sent:* 05 September 2023 21:20<br>
> *To:* Lakshmi Deverkonda <laksd@nvidia.com><br>
> *Subject:* Re: [lttng-dev] LTTNG LIB UST Crash<br>
> External email: Use caution opening links or attachments<br>
><br>
><br>
> Hi Lakshmi,<br>
><br>
> could you please provide us with the system details and version<br>
> information for LTTng tools and UST?<br>
><br>
> The bug reporting guidelines which cover the type of information<br>
> required to respond adequately questions can be found here:<br>
> <a href="https://lttng.org/community/#bug-reporting-guidelines">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flttng.org%2Fcommunity%2F%23bug-reporting-guidelines&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141743499%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ZU4mg%2BDNKMbtxCVA3kRuyCZAaj7yUH5bLz6p4oXpROA%3D&reserved=0</a>
<<a href="https://lttng.org/community/#bug-reporting-guidelines">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flttng.org%2Fcommunity%2F%23bug-reporting-guidelines&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141899697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=x0QzE9thuFtUFdNKd2qg0Fo4XSYqeTB4vbEBl88dGxE%3D&reserved=0</a>><br>
><br>
> Given that you are instrumenting a user space application, do you have a<br>
> minimal reproducer of the crash including the details of how the<br>
> application is invoked that you would be able to share?<br>
><br>
> Some types of user space applications required tracing helpers loaded<br>
> via LD_PRELOAD. More information can be found here<br>
> <a href="https://lttng.org/docs/v2.13/#doc-prebuilt-ust-helpers">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flttng.org%2Fdocs%2Fv2.13%2F%23doc-prebuilt-ust-helpers&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141899697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WpDm%2FpMZMb3EukOw9NF9L2GiMZpWeOAq3It8H8p%2BNSI%3D&reserved=0</a>
<<a href="https://lttng.org/docs/v2.13/#doc-prebuilt-ust-helpers">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flttng.org%2Fdocs%2Fv2.13%2F%23doc-prebuilt-ust-helpers&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141899697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WpDm%2FpMZMb3EukOw9NF9L2GiMZpWeOAq3It8H8p%2BNSI%3D&reserved=0</a>><br>
><br>
> If you're unable to share code or other log files due to company policy,<br>
> or require responses within a guaranteed time frame, EfficiOS offers<br>
> commercial support services:<br>
> <a href="https://www.efficios.com/services/">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.efficios.com%2Fservices%2F&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141899697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=92syXIQdFYIdm7jBG%2BEc%2FNFcSBujENDvSRG%2BaeyPCMs%3D&reserved=0</a>
<<a href="https://www.efficios.com/services/">https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.efficios.com%2Fservices%2F&data=05%7C01%7Claksd%40nvidia.com%7C5dec50116ea24aef578508dbaeee6437%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638296111141899697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=92syXIQdFYIdm7jBG%2BEc%2FNFcSBujENDvSRG%2BaeyPCMs%3D&reserved=0</a>><br>
><br>
> thanks,<br>
> kienan<br>
><br>
> p.s. Sorry for forgetting to CC you in my earlier reply to the list!<br>
><br>
> On 2023-09-05 02:30, Lakshmi Deverkonda via lttng-dev wrote:<br>
>> Hi All,<br>
>><br>
>> I am observing lttng crash while trying to interface LTTNG for one of my<br>
>> python3 application.<br>
>> I just tried the following things,<br>
>><br>
>> Added "import lttngust " in the code.<br>
>><br>
>> # lttng create clagd<br>
>> Session clagd created.<br>
>> Traces will be written in /root/lttng-traces/clagd-20230905-062210<br>
>><br>
>> # lttng enable-event --python clagd<br>
>> #lttng start<br>
>><br>
>> #service clagd start<br>
>> *<br>
>> *<br>
>> *cumulus-core: Running cl-support for core files<br>
>> "clagd-ust.95410.1693895062.core"*<br>
>><br>
>> #0 0x00007f134fb938eb in raise () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #1 0x00007f134fb7e535 in abort () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #2 0x00007f134fb7e40f in ?? () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #3 0x00007f134fb8c1a2 in __assert_fail () from<br>
>> /lib/x86_64-linux-gnu/libc.so.6<br>
>> #4 0x00007f134f1a9677 in lttng_ust_add_fd_to_tracker () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #5 0x00007f134f1bdcf4 in lttng_ust_elf_create () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #6 0x00007f134f1bf8de in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #7 0x00007f134fc8f957 in dl_iterate_phdr () from<br>
>> /lib/x86_64-linux-gnu/libc.so.6<br>
>> #8 0x00007f134f1bff6b in lttng_ust_dl_update () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #9 0x00007f134f1c061a in do_lttng_ust_statedump () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #10 0x00007f134f1b5ca9 in lttng_handle_pending_statedump () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #11 0x00007f134f1ab6d1 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #12 0x00007f134f1ad7eb in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #13 0x00007f134ff0dfa3 in start_thread () from<br>
>> /lib/x86_64-linux-gnu/libpthread.so.0<br>
>> #14 0x00007f134fc5506f in clone () from /lib/x86_64-linux-gnu/libc.so.6<br>
>><br>
>><br>
>> When I stop the lttng session, I see another core<br>
>><br>
>> #0 0x00007fad951988eb in raise () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> [Current thread is 1 (Thread 0x7fad9331f700 (LWP 2221103))]<br>
>> (gdb) bt<br>
>> #0 0x00007fad951988eb in raise () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #1 0x00007fad95183535 in abort () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #2 0x00007fad9518340f in ?? () from /lib/x86_64-linux-gnu/libc.so.6<br>
>> #3 0x00007fad951911a2 in __assert_fail () from<br>
>> /lib/x86_64-linux-gnu/libc.so.6<br>
>> #4 0x00007fad947e8d9f in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #5 0x00007fad947e98e3 in shm_object_table_destroy () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #6 0x00007fad947e4d9a in channel_destroy () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #7 0x00007fad947ba6b5 in lttng_session_destroy () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #8 0x00007fad947b47c6 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #9 0x00007fad947b4bac in lttng_ust_objd_unref () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #10 0x00007fad947b4bac in lttng_ust_objd_unref () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #11 0x00007fad947b4bac in lttng_ust_objd_unref () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #12 0x00007fad947b5304 in lttng_ust_objd_table_owner_cleanup () from<br>
>> /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #13 0x00007fad947b2b75 in ?? () from /lib/x86_64-linux-gnu/liblttng-ust.so.0<br>
>> #14 0x00007fad95512fa3 in start_thread () from<br>
>> /lib/x86_64-linux-gnu/libpthread.so.0<br>
>> #15 0x00007fad9525a06f in clone () from /lib/x86_64-linux-gnu/libc.so.6<br>
>><br>
>><br>
>> Can you please help here if I'm missing something. This is a critical<br>
>> task item for us but are currently stuck with multiple lttng crashes.<br>
>><br>
>> Regards,<br>
>> Lakshmi<br>
>><br>
>> _______________________________________________<br>
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