5 ms·

Hey. I work on Facebook's PHP toolchain, HipHop, which these days includes a debugger, interpreter, JIT compiler, and the ahead-of-time compiler. The fact that

by kmavm 14y ago

Hey. I work on Facebook's PHP toolchain, HipHop, which these days includes a debugger, interpreter, JIT compiler, and the ahead-of-time compiler. The fact that the AoT compiler uses C++ as a target doesn't change the input language, which really is PHP. E.g., $i = 0; $a[$i] = $i++; makes a different array than $i = 0; $a[$i + 0] = $i++;. We have to get all the nooks and crannies right because we use significant open source packages in PHP. The developer's usual routine is the same as someone using Zend; they write honest-to-goodness PHP and reload the page. There is no compilation involved; you instead are using the JIT (or until recently, an interpreter) that monitors the filesystem for changes and silently integrates them. Facebook devs use PHP exactly as everybody else does; they just do so with a different toolchain.

jmvoodoo 14y ago
I have to ask, because it's really been getting at me for a while honestly. How do your developers react to that? I mean, you guys are known for going after the best and the brightest. People who have worked hard to perfect their craft. These people tend to have strong opinions when it comes to language design. How do you get them from that point to "ok, now write some php code" ?
- cletus 14y ago
  That's easy: the best recognize languages are just a means to an end. Language snobbery, in my experience, tends to be highly correlated with being a "wannabe" rather than "great" and a useful filter. You will find any number of C/C++ programmers who think you can't write anything in Java. Many Java programmers think you can't write anything (beyond 100 lines) in Python. Many Python programmers think you can't (or simply shouldn't) write anything in PHP. And so on. Some people are insecure. Some people can't separate their language from themselves (and see a criticism of their language as a criticism of them as people). Some people exemplify the Dunning-Kruger effect [1]. Some, like teenagers, are just asserting their identities. Some simply have biases that are mental blocks. [1]: http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
  - tomjen3 14y ago
    Not all languages are equal. (if they are, why not just write everything in assembly?)
  - dxbydt 14y ago
    That's a well-reasoned but rather lazy response imo. Ppl who have strong opinions when it comes to language design have strong opinions when it comes to language design. Ppl who think languages are just a means to an end think languages are just a means to an end. These are two differenty species and indicative of their particular worldview, attitude and preferences. To use that as any kind of filter is silly. Lets not look at CS for a second...If you want to know what a Stieltjes integral is, a probabilist will tell you one thing, a functional analyst another, and a measure theorist will give you yet another more pedantic definition. There's no right or wrong definition here...every one is coming at it with the tools they are more well versed in. The probabilist is the end-user, so to speak. He can't do his day to day work without internalizing it, because his bread and butter, the PDFs and CDFs of all the distributions he deals with, comes from Stieltjes. The functional analyst is going to use Stieltjes when he deals with Banach spaces, but otherwise he has other preoccupations. The measure theorist studies Stieltjes in depth because it goes to the very foundantion of measure theory...but he isn't really an end-user. Now back to CS...a C++ programmer will think of Java as an interesting toy because you don't get union types and pointers & so forth. The Java guy will think of Python as an interesting toy, and the Python guy thinks PHP is an interesting toy. None of this means any of these people are insecure or being a teenager. If the only goal in life is "languages as means to an end" where end = $$$ in the short term, then yeah, lets just cut to the chase and do PHP. But there are other goals, yeah ?
  - ScottBurson 14y ago
    You have obviously never worked on a million-line codebase. When you have crap like this in your language: > E.g., $i = 0; $a[$i] = $i++; makes a different array than $i = 0; $a[$i + 0] = $i++; you have no hope of making a truly large program work. There are just too many sources of itsy bitsy bugs; you'll never find them all. (I'm not a PHP user; I have no idea why those are different arrays. Don't bother explaining; I don't want to know.)
- rargulati 14y ago
  I'm not the best and the brightest, but I'm sure the people they are going after are more excited and concerned with the quality and quantity of problems that facebook is in the unique position to solve. They could probably care less what they use to solve said problems.
- xxbondsxx 14y ago
  The best and the brightest appreciate the technical, product, and engineering challenges of Facebook and certainly don't waste their time whining about a language or feeling entitled.
  - tomjen3 14y ago
    Some of us like to write good code in a good language too. Maybe you should be the one to stop being so arrogant as to tell other people what they should feel.
- kmavm 14y ago
  The aspects of PHP that are bad (and there are more than a few) are easily tooled around. We have a review-time tool that parses your PHP, symbolically executes it, and looks for dubious idioms, flagging them for you and your reviewer. Meanwhile, PHP gets a number of things very right. For instance: * State: there is none across requests. Oh sure, there's APC, and the filesystem, and databases, etc., but those are all accessed via libraries. There is no PHP-level state that survives a request, which provides natural fault isolation: a request which goes wrong doesn't take the server down with it, or live on to corrupt other requests. * Concurrency: PHP's concurrency model is the web request. If you want to run some code in parallel, curl to localhost. If you wrap an appropriate library around this, it looks just like Erlang's actors. This is shared-nothing concurrency, which turns out to be a compelling local maximum. * Interactivity: The development workflow PHP provides is very productive. You save and load the page. You don't save, optionally recompile, restart the server, wait for it to initialize, forget what's different from the last three times you tried this because this has all taken three minutes and you forgot to write it down, etc. These three things turn out to be among the most important parts of a server-side language, and PHP gets them very, very right. The rightness was accidental, not by design, but this doesn't make it any less right. Also, the language itself can be improved. In the HipHop toolchain, -v Eval.EnableHipHopSyntax=true turns on a bunch of (backwards-compatible) features we've added to our PHP dialect, the most notable of which are XHP (syntax for using XML literals as PHP expressions) and generators (inspired by Python's, using similar 'yield' syntax). I put up some sample code for a talk just the other day, if you're curious: https://github.com/kmafb/hiphop-samples https://github.com/kmafb/hiphop-samples
  - swah 14y ago
    Is that tooling you mentioned related to/uses 'pfff' ? (https://github.com/facebook/pfff https://github.com/facebook/pfff)
    - kmavm 14y ago
      Yes, exactly. Thanks for mentioning it.
  - dxbydt 14y ago
nicholassmith 14y ago
I should have expected someone with more knowledge of the system on HackerNews :) What I mean is that whilst you guys at Facebook are using PHP you're not using it in the sense of 'we write code anywhere and deploy it anywhere'. There's an additional build step in between the developers and the final product, rather than just straight up serving PHP as is which is one of the biggest PHP recommendations. Although HipHop is open source so I guess you could still say it's within reach of all developers.
- Jach 14y ago
  > ... 'we write code anywhere and deploy it anywhere'. There's an additional build step in between the developers and the final product, rather than just straight up serving PHP as is which is one of the biggest PHP recommendations. According to him there's no explicit build step the devs have to perform and they're just writing PHP and using open source packages--meaning they are in fact making use of the "write once run anywhere" ideal at least in some places since the open source packages were made to run on Zend and now they don't. The "write once run anywhere" ideal is kind of a myth anyway since there's always configurations to do, and language-wise was even more of a myth when PHP 5.3 was new. (Some hosts still don't support it, and I'm sure a lot of us remember hosting services who dragged their feet just getting off PHP 4.) It seems like you think the Zend backend is the One True PHP runtime and anything else isn't PHP. This is like saying PyPy isn't Python. It's just a bad argument.
  - nicholassmith 14y ago
    Hm, I possibly need to clarify it up a bit. Now, as far as I understand it the Zend backend takes the PHP code, creates opcodes and executes it in a VM, whereas HipHop takes the code, compiles it down to C++, compiles it again with G++ then runs the resulting C++ binary instead. To me at that stage HipHop is no longer a backend, but an entire build system transforming the language away from PHP. Like I said, I'm not as intimately familiar with the system, but I thought it was along the lines of they have a dynamic system for local development, and when they serve it up it's run through the HipHop compile process.

by kmavm 14y ago

jmvoodoo 14y ago

I have to ask, because it's really been getting at me for a while honestly. How do your developers react to that? I mean, you guys are known for going after the best and the brightest. People who have worked hard to perfect their craft. These people tend to have strong opinions when it comes to language design. How do you get them from that point to "ok, now write some php code" ?

cletus 14y ago
That's easy: the best recognize languages are just a means to an end. Language snobbery, in my experience, tends to be highly correlated with being a "wannabe" rather than "great" and a useful filter. You will find any number of C/C++ programmers who think you can't write anything in Java. Many Java programmers think you can't write anything (beyond 100 lines) in Python. Many Python programmers think you can't (or simply shouldn't) write anything in PHP. And so on. Some people are insecure. Some people can't separate their language from themselves (and see a criticism of their language as a criticism of them as people). Some people exemplify the Dunning-Kruger effect [1]. Some, like teenagers, are just asserting their identities. Some simply have biases that are mental blocks. [1]: http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
- tomjen3 14y ago
  Not all languages are equal. (if they are, why not just write everything in assembly?)
- dxbydt 14y ago
  That's a well-reasoned but rather lazy response imo. Ppl who have strong opinions when it comes to language design have strong opinions when it comes to language design. Ppl who think languages are just a means to an end think languages are just a means to an end. These are two differenty species and indicative of their particular worldview, attitude and preferences. To use that as any kind of filter is silly. Lets not look at CS for a second...If you want to know what a Stieltjes integral is, a probabilist will tell you one thing, a functional analyst another, and a measure theorist will give you yet another more pedantic definition. There's no right or wrong definition here...every one is coming at it with the tools they are more well versed in. The probabilist is the end-user, so to speak. He can't do his day to day work without internalizing it, because his bread and butter, the PDFs and CDFs of all the distributions he deals with, comes from Stieltjes. The functional analyst is going to use Stieltjes when he deals with Banach spaces, but otherwise he has other preoccupations. The measure theorist studies Stieltjes in depth because it goes to the very foundantion of measure theory...but he isn't really an end-user. Now back to CS...a C++ programmer will think of Java as an interesting toy because you don't get union types and pointers & so forth. The Java guy will think of Python as an interesting toy, and the Python guy thinks PHP is an interesting toy. None of this means any of these people are insecure or being a teenager. If the only goal in life is "languages as means to an end" where end = $$$ in the short term, then yeah, lets just cut to the chase and do PHP. But there are other goals, yeah ?
- ScottBurson 14y ago
  You have obviously never worked on a million-line codebase. When you have crap like this in your language: > E.g., $i = 0; $a[$i] = $i++; makes a different array than $i = 0; $a[$i + 0] = $i++; you have no hope of making a truly large program work. There are just too many sources of itsy bitsy bugs; you'll never find them all. (I'm not a PHP user; I have no idea why those are different arrays. Don't bother explaining; I don't want to know.)
rargulati 14y ago
I'm not the best and the brightest, but I'm sure the people they are going after are more excited and concerned with the quality and quantity of problems that facebook is in the unique position to solve. They could probably care less what they use to solve said problems.
xxbondsxx 14y ago
The best and the brightest appreciate the technical, product, and engineering challenges of Facebook and certainly don't waste their time whining about a language or feeling entitled.
- tomjen3 14y ago
  Some of us like to write good code in a good language too. Maybe you should be the one to stop being so arrogant as to tell other people what they should feel.
kmavm 14y ago
The aspects of PHP that are bad (and there are more than a few) are easily tooled around. We have a review-time tool that parses your PHP, symbolically executes it, and looks for dubious idioms, flagging them for you and your reviewer. Meanwhile, PHP gets a number of things very right. For instance: * State: there is none across requests. Oh sure, there's APC, and the filesystem, and databases, etc., but those are all accessed via libraries. There is no PHP-level state that survives a request, which provides natural fault isolation: a request which goes wrong doesn't take the server down with it, or live on to corrupt other requests. * Concurrency: PHP's concurrency model is the web request. If you want to run some code in parallel, curl to localhost. If you wrap an appropriate library around this, it looks just like Erlang's actors. This is shared-nothing concurrency, which turns out to be a compelling local maximum. * Interactivity: The development workflow PHP provides is very productive. You save and load the page. You don't save, optionally recompile, restart the server, wait for it to initialize, forget what's different from the last three times you tried this because this has all taken three minutes and you forgot to write it down, etc. These three things turn out to be among the most important parts of a server-side language, and PHP gets them very, very right. The rightness was accidental, not by design, but this doesn't make it any less right. Also, the language itself can be improved. In the HipHop toolchain, -v Eval.EnableHipHopSyntax=true turns on a bunch of (backwards-compatible) features we've added to our PHP dialect, the most notable of which are XHP (syntax for using XML literals as PHP expressions) and generators (inspired by Python's, using similar 'yield' syntax). I put up some sample code for a talk just the other day, if you're curious: https://github.com/kmafb/hiphop-samples https://github.com/kmafb/hiphop-samples
- swah 14y ago
  Is that tooling you mentioned related to/uses 'pfff' ? (https://github.com/facebook/pfff https://github.com/facebook/pfff)
  - kmavm 14y ago
    Yes, exactly. Thanks for mentioning it.
- dxbydt 14y ago

nicholassmith 14y ago

I should have expected someone with more knowledge of the system on HackerNews :) What I mean is that whilst you guys at Facebook are using PHP you're not using it in the sense of 'we write code anywhere and deploy it anywhere'. There's an additional build step in between the developers and the final product, rather than just straight up serving PHP as is which is one of the biggest PHP recommendations. Although HipHop is open source so I guess you could still say it's within reach of all developers.

Jach 14y ago
> ... 'we write code anywhere and deploy it anywhere'. There's an additional build step in between the developers and the final product, rather than just straight up serving PHP as is which is one of the biggest PHP recommendations. According to him there's no explicit build step the devs have to perform and they're just writing PHP and using open source packages--meaning they are in fact making use of the "write once run anywhere" ideal at least in some places since the open source packages were made to run on Zend and now they don't. The "write once run anywhere" ideal is kind of a myth anyway since there's always configurations to do, and language-wise was even more of a myth when PHP 5.3 was new. (Some hosts still don't support it, and I'm sure a lot of us remember hosting services who dragged their feet just getting off PHP 4.) It seems like you think the Zend backend is the One True PHP runtime and anything else isn't PHP. This is like saying PyPy isn't Python. It's just a bad argument.
- nicholassmith 14y ago
  Hm, I possibly need to clarify it up a bit. Now, as far as I understand it the Zend backend takes the PHP code, creates opcodes and executes it in a VM, whereas HipHop takes the code, compiles it down to C++, compiles it again with G++ then runs the resulting C++ binary instead. To me at that stage HipHop is no longer a backend, but an entire build system transforming the language away from PHP. Like I said, I'm not as intimately familiar with the system, but I thought it was along the lines of they have a dynamic system for local development, and when they serve it up it's run through the HipHop compile process.