I was answering another question here and realised how shaky my knowledge of Julia array storage is, regarding inline storage. Somewhere (?) I read that if your struct is isbits and immutable, it can be stored directly inline in an array. This precludes a struct that stores an array, or a reference…

[image] torrance: The first is regarding the isbits requirement: why is this needed? Being stored inline exactly means that all of the data for the element is in one place with a fixed size; when the data is not all in one place, like a struct holding a Vector, then it’s just not considered i…

[image] Benny: Being stored inline exactly means that all of the data for the element is in one place with a fixed size; when the data is not all in one place, like a struct holding a Vector, then it’s just not considered inline. That doesn’t really answer my question, sorry. Consider this st…

[image] Immutables with reference-fields: Why boxed? Internals & Design One of the most painful things in julia is that there is no zero-cost abstraction for bundling gc-visible references with anything. This manifests in allocating views, allocating Tuple{Vector{Int}, Int…

@jar1 Right, so this is a limitation imposed by the GC?

[image] torrance: b is just a struct itself, with a length, dimension, capacity and pointer, and those are fixed in size. Well, not for Julia Vectors. You can push! and pop! elements onto or off from the end of Vectors (length changes, capacity always increases), for instance, and when it sta…

That is a really old thread, I think v1.5 (August 2020) fixed that issue. But there are issues that Restack seems to still help with, just not the stated purpose of stack-allocating “immutable” structs containing heap references (quotes because many non-mutable struct are in fact semantically mutabl…

On arrays with inline elements (vs pointer indirection)

General Usage

jar1 October 4, 2022, 7:25am 4

Topic		Replies	Views
Are the entries in a vector of immutable structs stored in place, or is there always a pointer to the heap? Performance	10	865	January 9, 2020
StaticArrays as vector elements General Usage	2	659	March 25, 2020
Mutable struct vs Ref in an immutable one? General Usage question , type , struct , mutable-structure	7	1057	November 28, 2024
Memory layout of structs with mutable fields Performance	42	3606	March 3, 2019
Understanding how an array of structures works General Usage question , arrays , struct	31	6403	October 31, 2021

On arrays with inline elements (vs pointer indirection)

Related topics