It does scale on modern hardware pretty fine... and I say that as have written tons of epoll networking layer (with a single buffer, no copy, parse off the netw

It does scale on modern hardware pretty fine... and I say that as have written tons of epoll networking layer (with a single buffer, no copy, parse off the network buffer, etc.) Mid 2000s there were tons of benchmarks on Java NIO. Until you get into 10k connections thread's overhead and context switching is nothing to worry about. Also OS kernels got better at handling thousands of threads. Writing a thousands connection server turns into writing a proper scheduler. The only downside of thread-per-conn are the latency non-guarantees, on short packages and long lasting connections (+the extra costs of context switches) as you rely on the OS scheduler mercy to do the right thing.