I think we have a case of mistaken Zolton's--or was it Zoltan's? (^_-)
On Oct 23, 2009, at 2:34 PM, Zoltan Lajos Kis <[email protected]> wrote:
Paul Davis wrote:
Hello,
You can use the erts_debug:size(Term) and erts_debug:flat_size(Term)
functions. They are somewhat
documented here: http://www.erlang.org/doc/efficiency_guide/processes.html
.
Note that the returned
value is in words and not bytes (see erlang:system_info
(wordsize). ).
Zoltan.
Zachary,
Most interesting, but I'm a bit confused by what its reporting:
1> erts_debug:size("stuff") * erlang:system_info(wordsize).
80
2> size(term_to_binary("stuff")).
9
Is it really using 80 bytes internally to represent that?
Paul Davis
Hello.
"stuff" is a linked list ( [115,116,117,102,102] ) built of cons
cells,
each consisting of one handler (pointer) to the current item, and
one to the next cons cell.
That is ten pointers each taking a word, 10 x 8 = 80 bytes in a 64-
bit OS.
Converted to binary it is stored as you would expect it to be (in 5
bytes), plus you get some
overhead (version info, metadata, list length, whatever) pumping it
up to 9 bytes.
Btw I believe the erts_debug:size() functions only deal with the
size of the term structure, so they
will behave odd if used with binaries.
Zoltan (who is definitely not Zolton ;))
