[lttng-dev] Valgrind Memory Error in lttng-relayd

Mon Jul 6 12:28:13 EDT 2015

Yes, I have both 32 bit as well as 64 bit apps running.

On Mon, Jul 6, 2015 at 8:23 PM, Jérémie Galarneau <
jeremie.galarneau at efficios.com> wrote:

> Are you running both 32 and 64-bits apps at once?
>
> Jérémie
>
> On Mon, Jul 6, 2015 at 12:10 AM, Aravind HT <aravind.ht at gmail.com> wrote:
>
>> This is how I am creating the session and using
>>
>>
>> lttng-relayd -o /var/tmp/lttng-traces -d
>>
>> lttng-sessiond --consumerd32-path /usr/lib/lttng/libexec/lttng-consumerd
>> --consumerd32-libdir /usr/lib/ --consumerd64-path
>> /usr/lib64/lttng/libexec/lttng-consumerd --consumerd64-libdir /usr/lib64/
>> -b --no-kernel
>>
>>
>>
>> lttng  --no-sessiond create mysession --live 2000000 -U net://128.0.0.4
>>
>> lttng enable-channel mychannel --userspace --buffers-pid -s mysession
>> --tracefile-size 2000000 --tracefile-count 2
>>
>> lttng enable-event --channel mychannel --userspace --all --exclude
>> 'ust_libc:*' -s mysession
>>
>> lttng start mysession
>>
>> lttng list
>>
>>
>> At present, I am not trying to enable new channels. The above is pretty
>> much what I do.
>>
>>
>>
>>
>> On Sat, Jul 4, 2015 at 1:26 AM, Jérémie Galarneau <
>> jeremie.galarneau at efficios.com> wrote:
>>
>>> Can you share a bit more information about the session configurations in
>>> your use case?
>>> Are you creating and destroying new sessions, tracing in per-pid or uid
>>> mode, enabling new channels, etc.
>>>
>>> Also, is this in "live" mode or are you just streaming to the relay
>>> daemon? (lttng create --set-url net://somewhere)
>>>
>>> Jérémie
>>>
>>>
>>> On Fri, Jul 3, 2015 at 3:30 PM, Jérémie Galarneau <
>>> jeremie.galarneau at efficios.com> wrote:
>>>
>>>>
>>>>
>>>> On Fri, Jul 3, 2015 at 1:48 PM, Aravind HT <aravind.ht at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> Thanks for replying.
>>>>>
>>>>> I have a daemon which i'm using for some CLI application, this forks
>>>>> whenever invoked but never exec()'s and am using lttng for tracing this and
>>>>> a few other apps.
>>>>> I have a script that I run to stress test this daemon; this I think
>>>>> means lttng is also being stressed.
>>>>> As soon as I run this script, after a few streams are created, I
>>>>> sometimes see a soft hang as mentioned in my previous thread
>>>>> http://lists.lttng.org/pipermail/lttng-dev/2015-May/024533.html
>>>>> or
>>>>> I see lttng-relayd coring.
>>>>>
>>>>> In short, an app that calls quite a bit of fork and exits which is
>>>>> being traced with other normal apps that run forever should re-create the
>>>>> problem.
>>>>>
>>>>> To run valgrind, use the -DVALGRIND when building, your can grep the
>>>>> code for what this does.
>>>>> Kill the valgrind  proc with -TERM to produce the logs.
>>>>>
>>>>>
>>>> Doh, of course! :-)
>>>>
>>>>
>>>>> This is the command and the options that I use to run valgrind
>>>>>
>>>>> valgrind --tool=memcheck --leak-check=full -v --log-file=/tmp/test
>>>>> --trace-children=yes  /usr/bin/lttng-relayd -o /var/log/lttng-traces -d
>>>>>
>>>>>
>>>>>
>>>>> I have tried the fix detailed in the checkin
>>>>> http://git.lttng.org/?p=lttng-tools.git;a=commitdiff;h=cd2ef1ef1d54ced9e4d0d03b865bb7fc6a905f80
>>>>>
>>>>> and it seems to work for me. This however only solves the relayd core,
>>>>> but I still see the "soft hang" happening.
>>>>>
>>>>
>>>>> Can some one please tell me how the above fix is missing from the
>>>>> source ?
>>>>>
>>>>
>>>> Somehow it appears this was reverted by this commit:
>>>>
>>>> https://github.com/lttng/lttng-tools/commit/1dc0526df43f2b5f86ef451e4c0331445346b15f
>>>>
>>>> I'm trying to reproduce the problem here.
>>>>
>>>> Jérémie
>>>>
>>>>
>>>>>
>>>>> Regards,
>>>>>
>>>>> Aravind.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Fri, Jul 3, 2015 at 8:36 PM, Jérémie Galarneau <
>>>>> jeremie.galarneau at efficios.com> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Thanks for the detailed report. Can you provide a sequence of steps
>>>>>> that leads to this problem?
>>>>>> Also, did you modify lttng-relayd at all to be able to run valgrind?
>>>>>> I seem to remember valgrind not supporting clone().
>>>>>>
>>>>>> Thanks,
>>>>>> Jérémie
>>>>>>
>>>>>> On Thu, Jul 2, 2015 at 12:42 PM, Aravind HT <aravind.ht at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Possible Solution :
>>>>>>>
>>>>>>> The following changes seem to be missing from the actual code
>>>>>>>
>>>>>>>
>>>>>>> http://git.lttng.org/?p=lttng-tools.git;a=commitdiff;h=cd2ef1ef1d54ced9e4d0d03b865bb7fc6a905f80
>>>>>>>
>>>>>>>
>>>>>>> only the connection.h changes have been absorbed, while the main.c
>>>>>>> changes left out.
>>>>>>>
>>>>>>> On Mon, Jun 29, 2015 at 11:51 PM, Aravind HT <aravind.ht at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I ran valgrind on lttng-relayd for a soft hang issue that I had
>>>>>>>> reported earlier.
>>>>>>>> http://lists.lttng.org/pipermail/lttng-dev/2015-May/024533.html
>>>>>>>>
>>>>>>>> Below are the list of errors that I found.
>>>>>>>>
>>>>>>>> ==793== Thread 4:
>>>>>>>> ==793== Invalid write of size 8
>>>>>>>> ==793==    at 0x406038: cds_list_add (list.h:53)
>>>>>>>> ==793==    by 0x409442: queue_stream (main.c:1175)
>>>>>>>> ==793==    by 0x409AB7: relay_add_stream (main.c:1274)
>>>>>>>> ==793==    by 0x40C47A: relay_process_control (main.c:2099)
>>>>>>>> ==793==    by 0x40DBB1: relay_thread_worker (main.c:2574)
>>>>>>>> ==793==    by 0x5BDAFE2: start_thread (pthread_create.c:312)
>>>>>>>> ==793==    by 0x5ED8AFC: clone (clone.S:111)
>>>>>>>> ==793==  Address 0x6e09040 is 64 bytes inside a block of size 312
>>>>>>>> free'd
>>>>>>>> ==793==    at 0x4C2898C: free (in
>>>>>>>> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
>>>>>>>> ==793==    by 0x418EF8: rcu_destroy_stream (stream.c:33)
>>>>>>>> ==793==    by 0x5079C94: ??? (in /usr/lib64/liburcu.so.2.0.0)
>>>>>>>> ==793==    by 0x5BDAFE2: start_thread (pthread_create.c:312)
>>>>>>>> ==793==    by 0x5ED8AFC: clone (clone.S:111)
>>>>>>>> ==793==
>>>>>>>>
>>>>>>>> Are there any known bugs/fixes for these ?
>>>>>>>>
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Aravind.
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> lttng-dev mailing list
>>>>>>> lttng-dev at lists.lttng.org
>>>>>>> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Jérémie Galarneau
>>>>>> EfficiOS Inc.
>>>>>> http://www.efficios.com
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Jérémie Galarneau
>>>> EfficiOS Inc.
>>>> http://www.efficios.com
>>>>
>>>
>>>
>>>
>>> --
>>> Jérémie Galarneau
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>>
>>
>>
>
>
> --
> Jérémie Galarneau
> EfficiOS Inc.
> http://www.efficios.com
>
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