[erlang-questions] proplists vs. dicts memory usage

Kenneth Lundin <>
Mon Jan 18 15:33:26 CET 2010


You can measure how much space an Erlang term takes internally in the
Erlang VM with
the function erts_debug:flat_size(Term).

It takes any Erlang term as input and returns the number of machine-words needed
to store the term.

I.e each word is 32 bits in a 32bit VM and 64 bits in a 64 bit VM.

/Kenneth Erlang/OTP Ericsson

On Mon, Jan 18, 2010 at 3:15 PM, Sean Cribbs <> wrote:
> Is there information somewhere on the memory requirements of proplists vs.
> dicts for small numbers of keys (< 100)?  If not, is there a nice way to
> measure memory usage at runtime?  I'm trying to determine whether switching
> from a dict to a proplist will save space.
>
> If the difference is negligible, I'll have to figure out some other solution
> (I'm guessing this is the answer).
>
> Cheers,
>
> Sean Cribbs
>
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