5 ms·

I'm sure it was conscious and well-reasoned, but the OP's point still stands. Trying to build a reasonable forward-looking high-performance managed language ru

I'm sure it was conscious and well-reasoned, but the OP's point still stands. Trying to build a reasonable forward-looking high-performance managed language runtime platform is hard. Trying to build it atop of PHP is harder. The only way I could see this as being a smart long-term strategy is if the eventual goal is to isolate and retire PHP projects entirely (and PHP usage itself) over time. However, even then, with PHP gone, and Hack no longer necessary, you're still stuck maintaining your own incompatible VM / runtime. Is Facebook signing up to reproduce the CLR? Or do they have long term plans to somehow bridge the gap between HHVM and more established VMs/runtimes, where they can better share the maintenance load with the wider industry.

sanxiyn 13y ago
Maintaining your own VM is no big deal. Compared to Facebook, HHVM is a tiny codebase. A team made of relatively small number of people (high quality, but low quantity) can and do maintain VMs like HotSpot and V8. LuaJIT is maintained by a single person.
- teacup50 13y ago
  > Maintaining your own VM is no big deal. As someone who has worked on a VM, I couldn't disagree more. It can take years to hash out things as simple as ideally performing primitives for a target architecture, and then things change. Add to that the complexity of optimizing compilers, specification of byte code formats and a consistent virtual machine memory model that can be relied upon across architectures, and the art and science of highly concurrent garbage collectors, and your "no big deal" is a load of hogwash. Hotspot alone is nearly 20 years of big deal. > A team made of relatively small number of people (high quality, but low quantity) can and do maintain VMs ... The number of people doesn't matter in this equation; your small team of (expensive, rare, high quality people) can't build a world-class VM in a day. Or a month. Or a year. Maybe in 5 or 10 years, just ask Microsoft. > ... like HotSpot and V8. LuaJIT is maintained by a single person. LuaJIT's said "single person" has been working on it for what, 10 years? It's an extremely impressive implementation and I don't want to bag on it, but even still, it lags in certain areas, eg, its GC implementation isn't up to par with the state of the art. The author's skillset is extremely rare, and LuaJIT itself is an anomaly in the field. Using such a one-off example doesn't really hold water to prove that it's ideal for a company to internalize maintaining a VM for their own custom language built on top of PHP.
  - sanxiyn 13y ago
    I am not trying to belittle efforts necessary for the state of the art VM or programming language implementation. I get paid to do these stuffs, and I am on my third VM/PL project now. It is also true these things take time and not very parallelizable, so while man-month may not be that big, you can't make it faster by throwing more people. On the other hand, I maintain it still is no big deal compared to rewriting Facebook. I also maintain while skillset is rare, Facebook apparently had no trouble so far and will have no trouble in the future finding (I remind you, small number of) people to work on VM. I also remind you Facebook has been working on alternative PHP implementation for 6 years now, 2 years in private(2008~2010) and 4 years in public(2010~2014). It has been profitable for them for 6 years, will be profitable in the future, and profitability does not need "sharing maintenance load with the wider industry". They can maintain it fine thank you very much. Because, in the end, VM is no big deal.
    - teacup50 13y ago
      If they're wasting money on bad management decisions, they're wasting stockholder money. They're also continuing to propagate an outwardly facing engineering culture that will make it even harder to hire people to help dig them out of the PHP hole -- perpetuating this further. Your argument is simply another take on survivor bias fallacy. > I get paid to do these stuffs, and I am on my third VM/PL project now ... Because, in the end, VM is no big deal. You keep saying that, and yet, there keep being so few high quality VMs.
      - sanxiyn 13y ago
        What do you consider to be high quality VM? How many do you expect to see and how many do you find? Adaptive JIT and generational GC would be a good baseline. Limiting myself to open source VM, I think (at least) HotSpot, Mono, V8, JavaScriptCore, PyPy, SBCL, Racket qualify. J9, CLR, Chakra, Allegro CL also qualify, but not open source. SpiderMonkey, LuaJIT, HHVM lack generational GC. All these projects are actively developed, and there are doubtlessly more, e.g. I am not faimilar with Smalltalk VM, some of which are commercial. Research VM like JikesRVM, Maxine qualify. I believe Bartok qualifies too. I am not sure what you are arguing for. If you are arguing for Quercus route(PHP-on-JVM), I think it's unclear Quercus route is better than HHVM route. If you are arguing for not running existing PHP codebase, I think you are being unrealistic.

sanxiyn 13y ago

Maintaining your own VM is no big deal. Compared to Facebook, HHVM is a tiny codebase. A team made of relatively small number of people (high quality, but low quantity) can and do maintain VMs like HotSpot and V8. LuaJIT is maintained by a single person.

teacup50 13y ago
> Maintaining your own VM is no big deal. As someone who has worked on a VM, I couldn't disagree more. It can take years to hash out things as simple as ideally performing primitives for a target architecture, and then things change. Add to that the complexity of optimizing compilers, specification of byte code formats and a consistent virtual machine memory model that can be relied upon across architectures, and the art and science of highly concurrent garbage collectors, and your "no big deal" is a load of hogwash. Hotspot alone is nearly 20 years of big deal. > A team made of relatively small number of people (high quality, but low quantity) can and do maintain VMs ... The number of people doesn't matter in this equation; your small team of (expensive, rare, high quality people) can't build a world-class VM in a day. Or a month. Or a year. Maybe in 5 or 10 years, just ask Microsoft. > ... like HotSpot and V8. LuaJIT is maintained by a single person. LuaJIT's said "single person" has been working on it for what, 10 years? It's an extremely impressive implementation and I don't want to bag on it, but even still, it lags in certain areas, eg, its GC implementation isn't up to par with the state of the art. The author's skillset is extremely rare, and LuaJIT itself is an anomaly in the field. Using such a one-off example doesn't really hold water to prove that it's ideal for a company to internalize maintaining a VM for their own custom language built on top of PHP.
- sanxiyn 13y ago
  I am not trying to belittle efforts necessary for the state of the art VM or programming language implementation. I get paid to do these stuffs, and I am on my third VM/PL project now. It is also true these things take time and not very parallelizable, so while man-month may not be that big, you can't make it faster by throwing more people. On the other hand, I maintain it still is no big deal compared to rewriting Facebook. I also maintain while skillset is rare, Facebook apparently had no trouble so far and will have no trouble in the future finding (I remind you, small number of) people to work on VM. I also remind you Facebook has been working on alternative PHP implementation for 6 years now, 2 years in private(2008~2010) and 4 years in public(2010~2014). It has been profitable for them for 6 years, will be profitable in the future, and profitability does not need "sharing maintenance load with the wider industry". They can maintain it fine thank you very much. Because, in the end, VM is no big deal.
  - teacup50 13y ago
    If they're wasting money on bad management decisions, they're wasting stockholder money. They're also continuing to propagate an outwardly facing engineering culture that will make it even harder to hire people to help dig them out of the PHP hole -- perpetuating this further. Your argument is simply another take on survivor bias fallacy. > I get paid to do these stuffs, and I am on my third VM/PL project now ... Because, in the end, VM is no big deal. You keep saying that, and yet, there keep being so few high quality VMs.
    - sanxiyn 13y ago
      What do you consider to be high quality VM? How many do you expect to see and how many do you find? Adaptive JIT and generational GC would be a good baseline. Limiting myself to open source VM, I think (at least) HotSpot, Mono, V8, JavaScriptCore, PyPy, SBCL, Racket qualify. J9, CLR, Chakra, Allegro CL also qualify, but not open source. SpiderMonkey, LuaJIT, HHVM lack generational GC. All these projects are actively developed, and there are doubtlessly more, e.g. I am not faimilar with Smalltalk VM, some of which are commercial. Research VM like JikesRVM, Maxine qualify. I believe Bartok qualifies too. I am not sure what you are arguing for. If you are arguing for Quercus route(PHP-on-JVM), I think it's unclear Quercus route is better than HHVM route. If you are arguing for not running existing PHP codebase, I think you are being unrealistic.