I have been researching threading and come across several websites which all say contradicting statements about which and how many thread models exist. Some websites say there are only three: 1:1, M:1 and M:M, while others say the three are 1:1, M:1 and hybrid (M:N). Still others say there are four types, including 2-level threading?
Google and stack exchange haven't been able to come up with a clear answer as of yet. I was hoping for someone to shed some light on this situation, namely the difference (i.e pros & cons) between M:M, M:N and two-level threading types.