3 ms·

Right, I'm familiar with Spolsky's piece, but I think there are times when a rewrite is legitimate. I think that a situation where you must roll a completely cu

Right, I'm familiar with Spolsky's piece, but I think there are times when a rewrite is legitimate. I think that a situation where you must roll a completely custom in-house compiler that generates binaries which exceed 1 GB in size in order to get adequate performance of your app is a good candidate for a new architecture, despite Spolsky's claims. Spolsky's article discusses throwing out pages of code because the programmers "don't know what half of these API calls are for" and "[wanting] to build something grand" -- these are quite different impulses than the real-world problems staring Facebook in the face by its continued usage of PHP. I think also that there is a difference between writing a new backend for something that is solid and in place and just throwing the whole product out the window and re-imagining it from the ground up, and I think the latter is the kind of rewrite that should be avoided and considered dangerous. When you could throw 4-5 guys on a real C# or C++ rewrite and tell them the final product has to behave identically to the PHP version, you have a much less volatile situation. As for the PHP workflow, I agree it's nice not to have an intermediate step, but that intermediate step can usually be circumvented pretty rapidly by throwing a script or two (or just flipping a config option) into your development environment.

TeeWEE 15y ago
PHP is not such a bad language. Of course it has its quirks. However bad code is written by a bad developer, not by a bad language. You can write beautiful code in PHP too. And the huge code base from Facebook is impossible to rewrite it in even a few years. Throwing away knowledge, tools, and tested code.
nbm 15y ago
There is pretty much no way 4 to 5 guys could rewrite "www" in another language in parallel to continuing development from a hundred developers, no matter how long they had. However, 4 to 5 guys could write HipHop. What real-world problems do you see staring Facebook in the face in its continued usage of PHP? I'm no PHP fan, but many of the common PHP problems are avoided or mitigated in the code base.
ericd 15y ago
I think developing in PHP and compiling to C++/binary probably results in much higher developer productivity than developing in C++/C# directly. Developer salaries are undoubtedly their largest expense, by far, dwarfing those salaries of the people who make PHP performant and 1.5 gig binary updates sane.
- sciurus 15y ago
  I expect that running their datacenters is a larger expense than developer salaries. "In 2011, $606 million was allocated towards total capital investment in data center infrastructure by Facebook, which includes the cost of servers, networking equipment, construction, and storage." - http://www.colocationamerica.com/blog/facebook-data-center-infrastructure-expenditures-a-quick-analysis.htm http://www.colocationamerica.com/blog/facebook-data-center-i...
  - evgen 15y ago
    The assumption that migrating the entire www stack to something like C++ would help with the datacenter costs is not supported by reality. Please remember that the bits that are in PHP are mostly front-end code. This handles the presentation of the data, but the actual heavy-lifting and data manipulation is done by the back-end infrastructure which is mostly C/C++ with some Java thrown in for the hadoop bits.
    - nbm 15y ago
      I would disagree here - every percent CPU saved for the same workload is a 1% reduction in the number of machines needed. The number of web machines is sufficiently large that savings of even 1% are praiseworthy. Quite a bit of effort is expended to keep this going down and to the right (at least some of the time).
  - ericd 15y ago
    Ah, good point, my estimate of their hardware spending wasn't that high. With 3000+ employees, depending on average total compensation, it might be close. That said, I would still guess that they'd choose greater developer productivity and agility over savings on server costs. I wonder if there are any public benchmarks of compiled Hiphop vs. C++

TeeWEE 15y ago

PHP is not such a bad language. Of course it has its quirks. However bad code is written by a bad developer, not by a bad language. You can write beautiful code in PHP too. And the huge code base from Facebook is impossible to rewrite it in even a few years. Throwing away knowledge, tools, and tested code.

nbm 15y ago

There is pretty much no way 4 to 5 guys could rewrite "www" in another language in parallel to continuing development from a hundred developers, no matter how long they had. However, 4 to 5 guys could write HipHop. What real-world problems do you see staring Facebook in the face in its continued usage of PHP? I'm no PHP fan, but many of the common PHP problems are avoided or mitigated in the code base.

ericd 15y ago

I think developing in PHP and compiling to C++/binary probably results in much higher developer productivity than developing in C++/C# directly. Developer salaries are undoubtedly their largest expense, by far, dwarfing those salaries of the people who make PHP performant and 1.5 gig binary updates sane.

sciurus 15y ago
I expect that running their datacenters is a larger expense than developer salaries. "In 2011, $606 million was allocated towards total capital investment in data center infrastructure by Facebook, which includes the cost of servers, networking equipment, construction, and storage." - http://www.colocationamerica.com/blog/facebook-data-center-infrastructure-expenditures-a-quick-analysis.htm http://www.colocationamerica.com/blog/facebook-data-center-i...
- evgen 15y ago
  The assumption that migrating the entire www stack to something like C++ would help with the datacenter costs is not supported by reality. Please remember that the bits that are in PHP are mostly front-end code. This handles the presentation of the data, but the actual heavy-lifting and data manipulation is done by the back-end infrastructure which is mostly C/C++ with some Java thrown in for the hadoop bits.
  - nbm 15y ago
    I would disagree here - every percent CPU saved for the same workload is a 1% reduction in the number of machines needed. The number of web machines is sufficiently large that savings of even 1% are praiseworthy. Quite a bit of effort is expended to keep this going down and to the right (at least some of the time).
- ericd 15y ago
  Ah, good point, my estimate of their hardware spending wasn't that high. With 3000+ employees, depending on average total compensation, it might be close. That said, I would still guess that they'd choose greater developer productivity and agility over savings on server costs. I wonder if there are any public benchmarks of compiled Hiphop vs. C++