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<div class="moz-cite-prefix">Hi again :)<br>
<br>
Another thing that would be helpful is if you could create a crash
dump instead of a fprintf when the binary is wrongly moved, i.e.
call erl_exit(ERTS_DUMP_EXIT, "erts_current_bin !=
(pb->bytes)"); instead of the fprintf? Then you could isolate
the erlang code snippet that exercises the bug and I maybe could
create a smaller testcase... A simple testcase when diving into
the GC would be really helpful :)<br>
<br>
Cheers,<br>
/Patrik<br>
<br>
On 11/21/2012 11:21 AM, Denis Titoruk wrote:<br>
</div>
<blockquote
cite="mid:8436D993-C4FC-4822-B0E8-7A2D6AB2E0C9@gmail.com"
type="cite">
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<div>21.11.2012, â 13:44, Patrik Nyblom íàïèñàë(à):</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">Hi!<br>
On 11/20/2012 10:40 PM, Denis Titoruk wrote:<br>
</div>
<blockquote
cite="mid:79133563-669F-4FDD-8982-01DB7B321DA5@aboutecho.com"
type="cite"> <base href="x-msg://13417/">
<div>Hi,</div>
<div><br>
</div>
We've got the same error on R15B01, R15B02
<div>I've finished my investigation of this issue today
& here is result:</div>
<div><br>
</div>
<div>Let's assume we have the code:</div>
<div>encode_formats(Columns) -><br>
encode_formats(Columns, 0, <<>>).<br>
<br>
encode_formats([], Count, Acc) -><br>
<<Count:?int16, Acc/binary>>;<br>
<br>
encode_formats([#column{format = Format} | T], Count,
Acc) -><br>
encode_formats(T, Count + 1, <<Acc/binary,
Format:?int16>>).<br>
</div>
<div><br>
</div>
<div>So, <<Acc/binary,
Format:?int16>> translates to</div>
<div><br>
</div>
<div>
{bs_append,{f,0},{integer,16},0,7,8,{x,2},{field_flags,[]},{x,1}}.<br>
{bs_put_integer,{f,0},{integer,16},1,{field_flags,[signed,big]},{x,6}}.<br>
</div>
<div><br>
</div>
<div>There is GC execution in bs_append and it can
reallocate binary but there isn't
reassigning erts_current_bin which used
in bs_put_integer.</div>
<div><br>
</div>
<div>Fix:</div>
<div><br>
</div>
<div>erl_bits.c:<br>
Eterm<br>
erts_bs_append(Process* c_p, Eterm* reg, Uint live,
Eterm build_size_term,<br>
Uint extra_words, Uint unit)<br>
…<br>
if (c_p->stop - c_p->htop < heap_need) {<br>
(void) erts_garbage_collect(c_p, heap_need, reg,
live+1);<br>
}<br>
sb = (ErlSubBin *) c_p->htop;<br>
c_p->htop += ERL_SUB_BIN_SIZE;<br>
sb->thing_word = HEADER_SUB_BIN;<br>
sb->size = BYTE_OFFSET(used_size_in_bits);<br>
sb->bitsize = BIT_OFFSET(used_size_in_bits);<br>
sb->offs = 0;<br>
sb->bitoffs = 0;<br>
sb->is_writable = 1;<br>
sb->orig = reg[live];<br>
<br>
///////////////////////////////////////////////////////////////////</div>
<div>// add this lines</div>
<div>
<div>///////////////////////////////////////////////////////////////////</div>
</div>
<div> pb = (ProcBin *) boxed_val(sb->orig);</div>
<div> erts_current_bin = pb->bytes;<br>
erts_writable_bin = 1;<br>
///////////////////////////////////////////////////////////////////<br>
<br>
return make_binary(sb);<br>
…<br>
</div>
<div><br>
</div>
</blockquote>
Can you reproduce the bug and verify that this fix really
works? The thing is that binaries should *only* be
reallocated in the gc if there are no active writers, which
there obviously is here ( pb->flags |=
PB_ACTIVE_WRITER a few lines earlier), so the bug would be
in the detection of active writers in the gc if this code
change actually removes the crash.<br>
</div>
</blockquote>
<div><br>
</div>
<div>Yes, it works in my case. I haven't simple test case for
reproducing this bug (actually I run few processes to send
requests to pgsql)</div>
<div><br>
</div>
<div>
<div> pb = (ProcBin *) boxed_val(sb->orig);</div>
<div> if (erts_current_bin != (pb->bytes)) {</div>
<div> fprintf(stderr, "erts_current_bin !=
(pb->bytes)\n");</div>
<div> fflush(stderr);</div>
<div> }</div>
<div> erts_current_bin = pb->bytes;</div>
<div> erts_writable_bin = 1;</div>
</div>
<div><br>
</div>
<div><br>
</div>
<div>
<div>(jskit@siden)1> f(F), F = fun() ->
postgresql:equery('echo-customers', write, <<"some
query here">>, []) end.</div>
<div>#Fun<erl_eval.20.82930912></div>
<div>(jskit@siden)2> perftest:comprehensive(1000, F).</div>
<div>Sequential 100 cycles in ~1 seconds (100 cycles/s)</div>
<div>Sequential 200 cycles in ~2 seconds (106 cycles/s)</div>
<div>Sequential 1000 cycles in ~12 seconds (85 cycles/s)</div>
<div>Parallel 2 1000 cycles in ~8 seconds (132 cycles/s)</div>
<div>Parallel 4 1000 cycles in ~8 seconds (121 cycles/s)</div>
<div>Parallel 10 1000 cycles in ~8 seconds (119 cycles/s)</div>
<div>Parallel 100 1000 cycles in ~13 seconds (74 cycles/s)</div>
<div>[85,132,121,119,74]</div>
<div>(jskit@siden)3> perftest:comprehensive(1000, F).
</div>
<div>Sequential 100 cycles in ~1 seconds (83 cycles/s)
</div>
<div>Sequential 200 cycles in ~2 seconds (83 cycles/s)
</div>
<div>Sequential 1000 cycles in ~14 seconds (71 cycles/s)
</div>
<div>Parallel 2 1000 cycles in ~11 seconds (95 cycles/s)
</div>
<div>Parallel 4 1000 cycles in ~10 seconds (105 cycles/s)
</div>
<div>Parallel 10 1000 cycles in ~11 seconds (91 cycles/s)</div>
<div>Parallel 100 1000 cycles in ~13 seconds (76 cycles/s)</div>
<div>"G_i[L"</div>
<div>(jskit@siden)4> perftest:comprehensive(1000, F).</div>
<div>Sequential 100 cycles in ~1 seconds (88 cycles/s)</div>
<div>Sequential 200 cycles in ~2 seconds (85 cycles/s)</div>
<div>Sequential 1000 cycles in ~13 seconds (74 cycles/s)</div>
<div>Parallel 2 1000 cycles in ~9 seconds (109 cycles/s)</div>
<div>Parallel 4 1000 cycles in ~10 seconds (101 cycles/s)</div>
<div>Parallel 10 1000 cycles in ~11 seconds (95 cycles/s)</div>
<div>erts_current_bin != (pb->bytes)</div>
<div>Parallel 100 1000 cycles in ~13 seconds (77 cycles/s)</div>
<div>"Jme_M"</div>
</div>
<br>
<blockquote type="cite">
<div bgcolor="#FFFFFF" text="#000000"> <br>
<blockquote
cite="mid:79133563-669F-4FDD-8982-01DB7B321DA5@aboutecho.com"
type="cite">
<div><br>
</div>
<div>--</div>
<div>Cheers,</div>
<div>Denis</div>
</blockquote>
Cheers,<br>
/Patrik<br>
<blockquote
cite="mid:79133563-669F-4FDD-8982-01DB7B321DA5@aboutecho.com"
type="cite">
<div><br>
<div>
<div>20.11.2012, â 19:37, Musumeci, Antonio S
íàïèñàë(à):</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div text="#000000" bgcolor="#ffffff">
<div><br class="webkit-block-placeholder">
</div>
<div dir="ltr" align="left"><font color="#0000ff"
face="Arial" size="2">
<p align="left"><font color="#0000ff"
face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2">I've
got lots of cores... but they are all
from optimized builds.</font></font></font></p>
<font color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2">
<p dir="ltr" align="left">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.</p>
</font></font></font>
<p dir="ltr" align="left"><font
color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2">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.</font></font></font><font
color="#000000" face="Times New Roman"
size="3"> <span class="403263615-20112012"><font
color="#0000ff" face="Arial" size="2">Any
suggestions on debugging beam would be
appreciated. Compile options, etc.</font></span></font></p>
<p dir="ltr" align="left">Thanks.</p>
</font>
<p dir="ltr" align="left"><font color="#0000ff"
face="Arial" size="2"><font color="#0000ff"
face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2"><font
color="#0000ff" face="Arial" size="2">-antonio</font></font></font></font><br>
</p>
</div>
<div class="OutlookMessageHeader" dir="ltr"
align="left" lang="en-us">
<hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b><span
class="Apple-converted-space"> </span><a
moz-do-not-send="true"
href="mailto:erlang-bugs-bounces@erlang.org">erlang-bugs-bounces@erlang.org</a><span
class="Apple-converted-space"> </span>[<a
moz-do-not-send="true"
class="moz-txt-link-freetext"
href="mailto:erlang-bugs-bounces@erlang.org">mailto:erlang-bugs-bounces@erlang.org</a>]<span
class="Apple-converted-space"> </span><b>On
Behalf Of<span class="Apple-converted-space"> </span></b>Patrik
Nyblom<br>
<b>Sent:</b><span
class="Apple-converted-space"> </span>Monday,
November 19, 2012 8:55 AM<br>
<b>To:</b><span class="Apple-converted-space"> </span><a
moz-do-not-send="true"
href="mailto:erlang-bugs@erlang.org">erlang-bugs@erlang.org</a><br>
<b>Subject:</b><span
class="Apple-converted-space"> </span>Re:
[erlang-bugs] beam core'ing<br>
</font><br>
</div>
<div class="moz-cite-prefix">On 11/19/2012 02:01
PM, Musumeci, Antonio S wrote:<br>
</div>
<blockquote
cite="mid:51C6F20DC46369418387C5250127649B039D96@HZWEX2014N4.msad.ms.com"
type="cite">
<div><br class="webkit-block-placeholder">
</div>
<div><span lang="EN">
<p><span class="483463912-19112012"><font
face="Arial" size="2">I'm just
starting to debug this but figured I'd
send it along in case anyone has seen
this before.</font></span></p>
<p><span class="483463912-19112012"><font
face="Arial" size="2">64bit RHEL 5.0.1</font></span></p>
<p><span class="483463912-19112012"><font
face="Arial" size="2">built from
source beam.smp R15B02</font></span></p>
<p><span class="483463912-19112012"><font
face="Arial" size="2">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.</font></span></p>
</span></div>
</blockquote>
<font size="2"><font face="Arial">Yes! I've seen
it before and have tried for several months to
get a<font size="2"><span
class="Apple-converted-space"> </span>reproducable
example and a<font size="2"><span
class="Apple-converted-space"> </span></font>core
i can analyze here. I've had one core that
was<font size="2"><span
class="Apple-converted-space"> </span>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!<br>
<br>
<font size="2">Please email me any
findings, theories, cores dumps<font
size="2"><span
class="Apple-converted-space"> </span>-
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).<br>
<br>
<font size="2">The problem is<span
class="Apple-converted-space"> </span><font
size="2">that<span
class="Apple-converted-space"> </span><font
size="2">when the allocators
crash, the error is usually
somewhere else<font size="2">.</font><span
class="Apple-converted-space"> </span><font
size="2">A</font>ccess of
freed memory, double free or
something else doing horrid
things to memory. Ob<font
size="2">viously none of our
testsui<font size="2">tes e<font
size="2">xercise this bug
as<span
class="Apple-converted-space"> </span><font
size="2">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 er<font size="2">ts</font>_bs_append</font></font></font></font></font></font></font></font></font></font></font></font></font>,
so I'm pretty sure this has a connection to the
other users seeing the crash in the allocat<font
size="2">ors<font size="2">...</font></font><span
class="Apple-converted-space"> </span><br>
<br>
Cheers,<br>
Patrik<br>
<blockquote
cite="mid:51C6F20DC46369418387C5250127649B039D96@HZWEX2014N4.msad.ms.com"
type="cite">
<div><span lang="EN">
<p>#0 bf_unlink_free_block
(flags=<optimized out>,
block=0x6f00, allctr=<optimized
out>) at beam/erl_bestfit_alloc.c:789<br>
#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<br>
#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<br>
#3 mbc_alloc (allctr=0x6824600, size=295)
at beam/erl_alloc_util.c:1345<br>
#4 0x000000000045398d in
do_erts_alcu_alloc (type=164,
extra=0x6824600, size=295) at
beam/erl_alloc_util.c:3442<br>
#5 0x0000000000453a0f in
erts_alcu_alloc_thr_pref (type=164,
extra=<optimized out>, size=287) at
beam/erl_alloc_util.c:3520<br>
#6 0x0000000000511463 in erts_alloc
(size=287, type=<optimized out>) at
beam/erl_alloc.h:208<br>
#7 erts_bin_nrml_alloc (size=<optimized
out>) at beam/erl_binary.h:260<br>
#8 erts_bs_append (c_p=0x69fba60,
reg=<optimized out>,
live=<optimized out>,
build_size_term=<optimized out>,
extra_words=0, unit=8)<span
class="483463912-19112012"><span
class="Apple-converted-space"> </span></span>at
beam/erl_bits.c:1327<br>
#9 0x000000000053ffd8 in process_main ()
at beam/beam_emu.c:3858<span
class="Apple-converted-space"> </span><br>
#10 0x00000000004ae853 in
sched_thread_func (vesdp=<optimized
out>) at beam/erl_process.c:5184<span
class="483463912-19112012"><span
class="Apple-converted-space"> </span><br>
</span>#11 0x00000000005c17e9 in
thr_wrapper (vtwd=<optimized out>)
at pthread/ethread.c:106<span
class="483463912-19112012"><span
class="Apple-converted-space"> </span><br>
</span>#12 0x00002b430f39e73d in
start_thread () from
/lib64/libpthread.so.0<span
class="483463912-19112012"><span
class="Apple-converted-space"> </span><br>
</span>#13 0x00002b430f890f6d in clone ()
from /lib64/libc.so.6<span
class="483463912-19112012"><span
class="Apple-converted-space"> </span><br>
</span>#14 0x0000000000000000 in ?? ()</p>
</span></div>
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