[erlang-questions] debug erlang core dumps with gdb

Caragea Silviu <>
Tue Sep 13 16:04:34 CEST 2016


After I compiled erlang from sources I don't have any longer this issues. I
compiled with systemtap support.

Silviu

On Tue, Sep 13, 2016 at 12:50 PM, Caragea Silviu <>
wrote:

> Hello,
>
> I'm using the last erlang package from Erlang Solution (19.0 - seems
> 19.0.3 is available only if you are using esl-erlang) and I want to debug a
> generated core dump with GDB.
>
> The issue I facing is that the beam.smp seems is not including debugging
> symbols.
>
> I inspired myself from: https://www.erlang-solutions.
> com/blog/how-to-analyse-a-beam-core-dump.html
>
> I changed a nif library I have to generate a crash.
>
> when I run :
>
> gdb my_project/rel/myapp/erts-8.0/bin/beam.smp
> core.2_scheduler.14306.silviu-desktop.1473754498 -d
> /home/silviu/Desktop/otp_src_19.0/erts/emulator
>
> I get this warning first:
>
> Reading symbols from my_project/rel/myapp/erts-8.0/bin/beam.smp ...(no
> debugging symbols found)...done.
>
> Then when I type backtrace:
>
> #0  memset () at ../sysdeps/x86_64/memset.S:78
> #1  0x00007ffa712a75cc in fill_window () from /home/silviu/Desktop/my_
> project/rel/myapp/lib/ezlib-1.0/priv/ezlib_nif.so
> #2  0x00007ffa712a7f20 in deflate_slow () from /home/silviu/Desktop/my_
> project/rel/myapp/lib/ezlib-1.0/priv/ezlib_nif.so
> #3  0x00007ffa712a8fd0 in deflate () from /home/silviu/Desktop/my_
> project/rel/myapp/lib/ezlib-1.0/priv/ezlib_nif.so
> #4  0x00007ffa712a6527 in process_buffer (session=0x7ffa71700968,
> data=<optimized out>, len=<optimized out>) at c_src/ezlib.cc:103
> #5  0x00007ffa712a6abb in nif_zlib_process_buffer (env=0x7ffaaa13de00,
> argc=<optimized out>, argv=0x7ffab03c4180) at c_src/ezlib.cc:289
> #6  0x000000000044426f in process_main ()
> #7  0x00000000004ce1bd in ?? ()
> #8  0x00000000005f2fcb in ?? ()
> #9  0x00007ffaf10a2184 in start_thread (arg=0x7ffaaa13e700) at
> pthread_create.c:312
> #10 0x00007ffaf0bc737d in clone () at ../sysdeps/unix/sysv/linux/
> x86_64/clone.S:111
>
> I can see the stack correctly in the ezlib nif I have but not the erlang
> VM which called the nif which shows as ?? because of the leak of symbols.
>
> There is any way to fix this ?
>
> Also I have a second problem when I try to run in gdb:
>
> source /home/silviu/Desktop/otp_src_19.0/erts/etc/unix/etp-commands.in
>
> I get:
>
> %-----------------------------------------------------------
> ----------------
> % Use etp-help for a command overview and general help.
> %
> % To use the Erlang support module, the environment variable ROOTDIR
> % must be set to the toplevel installation directory of Erlang/OTP,
> % so the etp-commands file becomes:
> %     $ROOTDIR/erts/etc/unix/etp-commands
> % Also, erl and erlc must be in the path.
> %-----------------------------------------------------------
> ----------------
> etp-set-max-depth 20
> etp-set-max-string-length 100
> --------------- System Information ---------------
> OTP release: /home/silviu/Desktop/otp_src_19.0/erts/etc/unix/etp-
> commands.in:3812: Error in sourced command file:
> Cannot access memory at address 0x38003931
>
> Any idea what can be wrong ?
>
> Silviu
>
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