[erlang-questions] Hidden binaries

[Kirill Zaborsky]

Hello,
I have recently found some memory "leak" in our application. Leak is in
quotes because memory load seems to be constant under constant load. But
the problem is that I see some extra binaries for which there are no signs
in process_info.
In production we use our fork of OTP16BR3-1 (including some number of httpc
fixes) but it looks like that behaviour could be reproduced locally on my
machine with OTP 17.
I have tried to get any hints from recon but with not success.
The problem could be seen from the following Erlang shell lines:
-------------
(node@REDACTED)87> recon:bin_leak(20),erlang:memory().
[{total,30574120},
 {processes,6765096},
 {processes_used,6738520},
 {system,23809024},
 {atom,662409},
 {atom_used,652067},
 {binary,145760},
 {code,16742599},
 {ets,1037976}]
(node@REDACTED)88>
lists:sum([N||{P1,N,B}<-[{P,lists:sum([S||{_,S,_}<-B]),B} || {P,{binary,B}}
<- [{Pid,(catch process_info(Pid,binary))} || Pid <- processes()]]]).
17671
(node@REDACTED)89>
-------------
As you see erlang:memory/0 shows 146k of memory used by binaries but
erlang:process_info/2 shows information only about 18k
Is there any way I could find out where the missing 128k of memory is?
Is it possible to get all binaries contents without gowing to some
low-level tools like gdb (I'm not quite familiar with it yet)?
Possibly there are some system-level binaries?
In production I see not kilobytes but hunderds of megabytes and sometimes
it leads even to OOM crashes.
I run Gentoo on my desktop and in production we use Ubuntu Precise.
Thanks for any advice.

Best regards,
Kirill Zaborsky
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