[erlang-bugs] Strange Memory Allocation Crash

Sverker Eriksson <>
Wed Jul 7 14:52:51 CEST 2010


And this of course spins out of control because

do(100.0) -> done;

never matches exactly.

do(N) when N >= 100.0 -> done;

should put an end to the madness.

/Sverker


Björn-Egil Dahlberg wrote:
> On 2010-07-07 14:11, Björn-Egil Dahlberg wrote:
>> The error_logger can't consume the info messages you send at the rate
>> that that tight loop produces them.
>>
>> erl_crash.dump:
>> <0.5.0> error_logger Garbing (limited info) 27440736 182452560 7557980
>
> That is 7557980 messages in the msq-queue.
> To answer your question, use the crashdump viewer to examine crash 
> dump you just got.
>
> Eshell V5.8.1  (abort with ^G)
> 1> crashdump_viewer:start().
> WebTool is available at http://localhost:8888/
> Or  http://127.0.0.1:8888/
>
> // Björn-Egil
>
>
>>
>> Regards,
>> Björn-Egil
>> Erlang/OTP
>>
>> On 2010-07-07 13:27,  wrote:
>>>
>>>
>>> While try to do a quick check on which floats need to be rounded before
>>> trunking them to get valid results, I was able to crash the Erlang VM.
>>> I find
>>> it a bit strange as it happened rather quickly into something that I
>>> thought
>>> shouldn't be that intensive. I have tried this twice, and was
>>> wondering if
>>> this could be pointing to something else as a problem.
>>>
>>> Machine Info
>>> :~/sdb/work/gf_olympus/troy/trunk/tmp> uname -a
>>> Linux greyowl 2.6.31.12-0.2-default #1 SMP 2010-03-16 21:25:39 +0100
>>> x86_64
>>> x86_64 x86_64 GNU/Linux
>>> :~/sdb/work/gf_olympus/troy/trunk/tmp> erl --version
>>> Erlang R14A (erts-5.8) [source] [64-bit] [smp:2:2] [rq:2]
>>> [async-threads:0]
>>> [hipe] [kernel-poll:false]
>>>
>>>
>>> ============== CODE START
>>>
>>> -module(itest).
>>> -export([do/0]).
>>>
>>> do() ->
>>> do(0.0).
>>>
>>> do(100.0) ->
>>> done;
>>> do(Value) ->
>>> if trunc(Value * 100) =:= trunc(round(Value * 100)) ->
>>> do(Value + 0.01);
>>> true ->
>>> error_logger:info_msg("Value: ~p~n", [Value]),
>>> do(Value + 0.01)
>>> end.
>>>
>>> ============== CODE END
>>>
>>> The final result. (After 280 iterations of the function the following
>>> crash)
>>>
>>> =INFO REPORT==== 7-Jul-2010::11:33:07 ===
>>> Value: 2.7999999999999843
>>>
>>> Crash dump was written to: erl_crash.dump
>>> eheap_alloc: Cannot allocate 20672 bytes of memory (of type "heap").
>>> Aborted
>>>
>>>
>>> The code is attached
>>>
>>> I am a bit at a loss as to where to start troubleshooting this :)
>>>
>>
>
>
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