So, a 62.5 million edge LightGraphs.Graph should only take about a 1.25 gigs of memory, all-in. However, because the edges are being added to vectors within the datastructure, and each vector is doing its own memory allocation, we wind up with the Julia process taking ~6.5 gigs.
Given that we don't know the degree distribution of the graph before we load it (and therefore can't use sizehint! effectively), is there any way to reclaim the allocated-but-unused memory from all these vectors, with the accepted large performance hit that would come should we decide to add another edge?