[wahern]

That's an issue with the http/net libraries, not the concurrency model.

At really high throughout you can run into into issues with the kernel's networking and driver stack. I've encountered situations with my own homegrown event libraries (mostly C or Lua+C; I've never used Go) that were bottlenecked in the kernel. I've also seen issues that were fundamentally related to the use of poor buffering and processing pipeline strategies that resulted in horrible performance. For example, I can get an order of magnitude greater streaming throughput using my own protocol and framing implementations than when using ffmpeg's, though I use ffmpeg's codecs and a non-blocking I/O model in both cases, all in C. And that's because of how I structured the flow of data through my processing pipeline.

There's is no general model of concurrency that can solve that, and I've never seen any model that was easier in the abstract to tweak than any others. Those are implementation issues.