title: Which linear Optimization/Mixed Integer Optimization solver to use?
body: <p>I have a mathematical model, linear programming, with huge number of decision variables(>500K - 1M). Which of the open source software/library(java) can I use for my requirement? </p>
  
  <p>The complexity of the problem is fairly simple, with five constraints and a cost minimisation function but the size is huge.</p>
  
  <p>Please suggest me the best performing solver available(open-source or commercial/ any language), if there is nothing that can solve the problem.</p>