One trick to get to background-only threads

[xiaodai]

Thanks. I found it and I have been using it to do something silly

Faster sorting of DataFrames.jl via background ordering

I have had this idea for a long time, now I finally gave it a go and the results are amazing. So here’s the idea. Here sorting a large dataframe the algorithm roughly goes like this Perform a sortperm on the columns to sort by. This returns an idx of indices. Consider colX which his not a sort by column then colX[idx] would give order the colX in the right order. Repeat number 2 for all columns. There are room for improvement for 1 and 2 but 3 is low-hanging fruit. Once the dataframe is sor…