how to run out of memory: let binaries leverage the heap

davidwallin <>
Tue Feb 11 19:28:37 CET 2003


Hi,

(this is a very late response :)

I just tried the attached program on my OS X system running R9B-0 with 
shared heap enabled I couldn't see any growth. Is this problem a 
non-issue on PPC systems or with shared heap ?

On a Linux box running with HiPE enabled (but no shared heap) I doo see 
an increase but after a couple of iterations this happens:

memshow process size: 6749120
memshow process size: 6749604
memshow process size: 6750088
memshow process size: 1768
memshow process size: 1768
...

Any ideas what happens here ?


--david.

On Thursday, September 26, 2002, at 03:59 PM, Matthias Lang wrote:

> Hi,
>
> A problem that bites me a couple of times a year is this: some piece
> of code involving binaries causes the Erlang VM to expand its memory
> footprint enormously for no particularly good reason. The Erlang VM
> then dies because it can't allocate more ram.
>
> Here's how to do it:
>
>       1. Make the heap grow by doing something memory-intensive. Cross
>          your fingers and hope that you get left with a half-full heap.
>
>       2. Do something tail-recursive which involves creating a lot
>          binary garbage.
>
>       3. Watch the VM expand to many times the original heap size.
>
> The problem at the bottom of this is that the size of binaries created
> (or referenced) by a process has very little effect on when that
> process will be GCed next. Binaries can be large, the references to
> them are small.
>
> I've attached a little program which demonstrates this. On my machine
> (linux, x86), it'll happily eat 60M before a being GCed back down to
> 6M. On an embedded system with just 32M, this is a bit of a bummer.
>
> What's the solution? Specifying {fullsweep_after, 0} in the spawn
> option doesn't help much (as the attached example
> demonstrates). Forcing a GC immediately before a "binary-intensive"
> series of operations helps a lot. Any cleaner or better ideas?
>
> Does the (HIPE) unified heap put binaries on that heap?
>
> Matthias
>
> <eatmem.erl>



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