[julia-users] memory allocations when accessing tuple fields of a type

[Uri Patish]

Hi, I have to following types, 

typealias ElementSize 

typealias Element Array{Float64, 3}

type ElementBuffer
size::ElementSize
alloc::ElementSize
data::Element
end

The following function is called many times,

function set_size!(bf::ElementBuffer, sz::ElementSize, load_old_data::Bool 
= true)
  if (bf.alloc[1] < sz[1]) || (bf.alloc[2] < sz[2]) || (bf.alloc[3] < sz[3])
    old_data = bf.data
    bf.alloc = map(max, bf.alloc, sz)
    bf.data = Element(bf.alloc)
    if load_old_data
      load_body!(bf, old_data)
    end
end
bf.size = sz
  nothing
end

I've seen there is a lot of memory allocation going on, so I've benchmarked 
the former code using Julia's track-allocation=user option. The result was 
suprising, 

        - function set_size!(bf::ElementBuffer, sz::ElementSize, 
load_old_data::Bool = true)
1710097664   if (bf.alloc[1] < sz[1]) || (bf.alloc[2] < sz[2]) || 
(bf.alloc[3] < sz[3])
        0     old_data = bf.data
  2894592     bf.alloc = map(max, bf.alloc, sz)
 59783056     bf.data = Element(bf.alloc)
        0     if load_old_data
        0       load_body!(bf, old_data)
        -     end
        - end
        0 bf.size = sz
        0   nothing
        - end

After running the code in debug, I've seen that there is an allocation 
happening every time the alloc field is accessed. If I change the field 
type from a tuple to an array this phenomenon disappears. I can't figure 
out why this allocation is happening, any ideas?

Uri