RAM needed to initialise large matrices

[Sukera]

@c42f

(Edit: As a side note - it seems technically possible to do lazy zero fill in (a) the case that a large array happens to be allocated with mmap and MAP_ANONYMOUS somewhere deep in the allocator and (b) zero(eltype(a)) happens to be a bits type with a bit pattern of zeros. I think this would only help in specialized circumstances, though.)

For a detailed discussion on the challenges that would crop up almost immediately when trying this, check out Faster zeros with calloc. The TL;DR is that the cost of initialization doesn’t vanish but gets shifted to the first write instead and that growing such an array immediately looses the “zero initialized” property.