I believe it stays allocated until the object is removed. There's an old issue about providing a way to "shrink" the underlying storage: https://github.com/JuliaLang/julia/issues/2879
-Jacob On Wed, Oct 21, 2015 at 1:26 PM, Seth <[email protected]> wrote: > Thanks, Jacob and Stefan. What happens if you overestimate? Is the > allocated-but-not-used memory eventually freed, or is it tied up until the > object gets removed? > > On Wednesday, October 21, 2015 at 12:18:28 PM UTC-7, Stefan Karpinski > wrote: >> >> If you expect that you're going to have to push a lot of values onto a >> vector, you can avoid the cost of incremental reallocation by doing it once >> up front. >> >> On Wednesday, October 21, 2015, Jacob Quinn <[email protected]> wrote: >> >>> The way I came to understand was to just take a peak at the [source >>> code]( >>> https://github.com/JuliaLang/julia/blob/ae154d076a6ae75bfdb9a0a377a6a5f9b0e1096f/src/array.c#L670); >>> I find it pretty legible. The basic idea is that the underlying "storage" >>> of a Julia Array{T,N} can actually be (and often is) different than the >>> size(A) in Julia. sizehint! modifies that underlying storage without >>> changing the size(A) in Julia. >>> >>> -Jacob >>> >>> On Wed, Oct 21, 2015 at 12:46 PM, Seth <[email protected]> wrote: >>> >>>> I know it's good to use sizehint! with an estimate of the sizes of >>>> (variable-length) containers such as vectors, but I have a couple of >>>> questions I'm hoping someone could answer: >>>> >>>> 1) what are the benefits of using sizehint!? (How does it work, and >>>> under what circumstances is it beneficial?) >>>> 2) what are the implications (positive/negative, if any) of >>>> overestimating the size of a container? >>>> >>>> Thanks. >>>> >>> >>>
