[erlang-questions] Erlang string datatype [cookbook entry #1 - unicode/UTF-8 strings]

[Jon Watte]

Also, as long as the sub-binary is smaller than 64 bytes, the VM is
perfectly allowed to do the extraction itself, because small binaries are
process-local and thus can almost trivially be detected and extracted.

For example, I imagine the VM could keep a count of how many bytes are
referenced within a large binary (in addition to the actual ref count), as a
hint for when a large binary is unlikely to be beneficial to stay in RAM.
Implementation idea sketch: When a local heap references a global binary but
the total amount of referenced bytes within that binary is less than 50%,
the local heap will extract the piece it needs and release the global
reference. This would cause many degenerate cases to clean up themselves on
reference/use/collection (whenever you trigger this mechanism).

Sincerely,

jw


--
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whether we get there willingly or not, we shall soon have lower consumption
rates, because our present rates are unsustainable.



On Tue, Oct 25, 2011 at 1:04 AM, Loïc Hoguin <essen@REDACTED> wrote:

> On 10/25/2011 09:57 AM, Anthony Ramine wrote:
> > Le 25 oct. 2011 à 06:57, Richard O'Keefe a écrit :
> >
> >>> 6) Ideally, reference count immutable string data so that substring
> extraction is cheap.
> >>
> >> Java has cheap substring extraction without reference counting.
> >> However, be aware that doing this can lead to *huge* space leaks with
> very
> >> large source strings being retained for the sake of comparatively small
> >> substrings; there is a *reason* why Java's immutable String class comes
> with a
> >> copy() method!
> >
> > Don't we have the same problem with sub-binaries of large binaries?
> >
> > (Sorry for the dupe mail Richard, forgot to include the list)
>
> And that's why binaries come with a binary:copy/1 function.
>
> --
> Loïc Hoguin
> Dev:Extend
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