[erlang-bugs] beam core'ing

Musumeci, Antonio S <>
Tue Nov 20 16:37:45 CET 2012


I've got lots of cores... but they are all from optimized builds.

Has this been seen in other versions? We are keen to solve this because it's causing us pain in production. We hit another, older, memory bug (the 32bit values used in 64bit build)... and now this.

I'm going to be building and trying R15B01 to see if we hit it as well. I'll send any additional information I can. Any suggestions on debugging beam would be appreciated. Compile options, etc.

Thanks.

-antonio

________________________________
From:  [mailto:] On Behalf Of Patrik Nyblom
Sent: Monday, November 19, 2012 8:55 AM
To: 
Subject: Re: [erlang-bugs] beam core'ing

On 11/19/2012 02:01 PM, Musumeci, Antonio S wrote:

I'm just starting to debug this but figured I'd send it along in case anyone has seen this before.

64bit RHEL 5.0.1

built from source beam.smp R15B02

Happens consistently when trying to start our app and then just stops after a time. Across a few boxes. Oddly we have an identical cluster (hw and sw) and it never happens.

Yes! I've seen it before and have tried for several months to get a reproducable example and a core i can analyze here. I've had one core that was somewhat readable but had no luck in locating the beam code that triggered this. If you could try narrowing it down, I would be really grateful!

Please email me any findings, theories, cores dumps - anything! I really want to find this! The most interesting would be to find the snippet of erlang code that makes this happen (intermittently probably).

The problem is that when the allocators crash, the error is usually somewhere else. Access of freed memory, double free or something else doing horrid things to memory. Obviously none of our testsuites exercise this bug as neither our debug builds, nor our valgrind runs find it. It happens on both SMP and non SMP and is always in the context of the erts_bs_append, so I'm pretty sure this has a connection to the other users seeing the crash in the allocators...

Cheers,
Patrik

#0 bf_unlink_free_block (flags=<optimized out>, block=0x6f00, allctr=<optimized out>) at beam/erl_bestfit_alloc.c:789
#1 bf_get_free_block (allctr=0x6824600, size=304, cand_blk=0x0, cand_size=<optimized out>, flags=0) at beam/erl_bestfit_alloc.c:869
#2 0x000000000045343c in mbc_alloc_block (alcu_flgsp=<optimized out>, blk_szp=<optimized out>, size=<optimized out>, allctr=<optimized out>) at beam/erl_alloc_util.c:1198
#3 mbc_alloc (allctr=0x6824600, size=295) at beam/erl_alloc_util.c:1345
#4 0x000000000045398d in do_erts_alcu_alloc (type=164, extra=0x6824600, size=295) at beam/erl_alloc_util.c:3442
#5 0x0000000000453a0f in erts_alcu_alloc_thr_pref (type=164, extra=<optimized out>, size=287) at beam/erl_alloc_util.c:3520
#6 0x0000000000511463 in erts_alloc (size=287, type=<optimized out>) at beam/erl_alloc.h:208
#7 erts_bin_nrml_alloc (size=<optimized out>) at beam/erl_binary.h:260
#8 erts_bs_append (c_p=0x69fba60, reg=<optimized out>, live=<optimized out>, build_size_term=<optimized out>, extra_words=0, unit=8) at beam/erl_bits.c:1327
#9 0x000000000053ffd8 in process_main () at beam/beam_emu.c:3858
#10 0x00000000004ae853 in sched_thread_func (vesdp=<optimized out>) at beam/erl_process.c:5184
#11 0x00000000005c17e9 in thr_wrapper (vtwd=<optimized out>) at pthread/ethread.c:106
#12 0x00002b430f39e73d in start_thread () from /lib64/libpthread.so.0
#13 0x00002b430f890f6d in clone () from /lib64/libc.so.6
#14 0x0000000000000000 in ?? ()


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