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Read the article, very informative. Pleasantly surprised to find out that it doesn't mention at all language traits like syntax, but focuses on the features of

Read the article, very informative. Pleasantly surprised to find out that it doesn't mention at all language traits like syntax, but focuses on the features of Perl6's underlying VM, specifically MoarVM.

agumonkey 9y ago
Indeed, a GILless bytecode VM is worth a look.
- rurban 9y ago
  GIL less yes, but not lockless. The previous perl6 VM, parrot, had lockless threads, scaling linearly per native core. MoarVM even needs to lock on hash or array accesses, which is certainly not state of the art.
  - oconnor663 9y ago
    How did parrot write arrays from multiple threads without a lock somewhere in there?
    - bigleagueposter 9y ago
      The parrot threads didn't communicate with each other and you could wait until all of them finished. They provided a tiny subset of the functionality real threads offer but in a more efficient way.
    - rurban 9y ago
      You deferred updates to the owner via scheduler, with high prio, and continue. parrot threads are lock free but not wait free. The NQP compiler needed to know about threaded writes and schedule the update, with a semaphore, while the other threads continue. What MoarVM got better was everything else. The GC, the calling convention, the OO (6model), the jit. I was on my way to fix all the parrot damage done from the previous decade, because this would have enabled all architectures and proper threading for perl6, but then perl6 decided to kill it and go with Moar. And spread a lot of lies on threads.
      - pierrebai 9y ago
        I fail to see how using a semaphore to schedule work in another thread is "lock-free."
        rurban 9y ago
        Because you wait but you don't lock. And the wait is not 100x of an instruction, normally it's the same time as for one single instruction. Writes are fast and atomic, because there's no lock. Only the writer needs to wait a bit, not any other thread. Google for lock-free vs wait-free
petre 9y ago
Well, it should have mentioned Perl6 uses rational number math instead of floating point. I think this is a big advantage, since you can do more precise calculations using just the core language.

agumonkey 9y ago

Indeed, a GILless bytecode VM is worth a look.

rurban 9y ago
GIL less yes, but not lockless. The previous perl6 VM, parrot, had lockless threads, scaling linearly per native core. MoarVM even needs to lock on hash or array accesses, which is certainly not state of the art.
- oconnor663 9y ago
  How did parrot write arrays from multiple threads without a lock somewhere in there?
  - bigleagueposter 9y ago
    The parrot threads didn't communicate with each other and you could wait until all of them finished. They provided a tiny subset of the functionality real threads offer but in a more efficient way.
  - rurban 9y ago
    You deferred updates to the owner via scheduler, with high prio, and continue. parrot threads are lock free but not wait free. The NQP compiler needed to know about threaded writes and schedule the update, with a semaphore, while the other threads continue. What MoarVM got better was everything else. The GC, the calling convention, the OO (6model), the jit. I was on my way to fix all the parrot damage done from the previous decade, because this would have enabled all architectures and proper threading for perl6, but then perl6 decided to kill it and go with Moar. And spread a lot of lies on threads.
    - pierrebai 9y ago
      I fail to see how using a semaphore to schedule work in another thread is "lock-free."
      - rurban 9y ago
        Because you wait but you don't lock. And the wait is not 100x of an instruction, normally it's the same time as for one single instruction. Writes are fast and atomic, because there's no lock. Only the writer needs to wait a bit, not any other thread. Google for lock-free vs wait-free

petre 9y ago

Well, it should have mentioned Perl6 uses rational number math instead of floating point. I think this is a big advantage, since you can do more precise calculations using just the core language.