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It's combining the benefits from async models (state machines separated from os threads, thus more optimal for I/O bound workload), with the benefits from prope

• hashmash 2y ago
  Why is an async model better than using OS threads for an I/O bound workload? The OS is doing async stuff internally and shielding the complexity with threads. With virtual threads this work has shifted to the JVM. Can the JVM do threads better than the OS?
  • adgjlsfhk1 2y ago
    it can do a much better job because there isn't a security boundary. OS thread scheduling requires sys calls and invalidate a bunch of cache to prevent timing leaks
  • zokier 2y ago
    > Can the JVM do threads better than the OS? Yes. The JVM has far more opportunities for optimizing threads because it doesn't need to uphold 50 years of accumulated invariants and compatibility that current OSes do, and JVM has more visibilty on the application internals.
  • mrsilencedogood 2y ago
    "Why is an async model better than using OS threads for an I/O bound workload?" Because evented/callback-driven code is a nightmare to reason about and breaks lots of very basic tools, like the humble stack trace. Another big thing for me is resource management - try/finally don't work across callback boundaries, but do work within a virtual thread. I recently ported a netty-based evented system to virtual threads and a very long-standing issue - resource leakage - turned into one very nice try/finally block.
    • deleted 2y ago
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