[nrser]

it's the "good problem". and the good problem can always be solved, though lack of reliability can seriously hurt your growth. but that doesn't mean that it's as easy as people make it out to be.

i wrote and ran a big php app (Zynga's Mafia Wars). this is just about the app server (apache + php side), single-master MySQL will give you far greater problems at that scale.

everyone is tearing away adding features, and the code just keeps getting bigger. everything includes everything else. so you can't just start fresh with every request, it takes way too long. so you use APC or whatever. now you have global shared state (and people start using it), but as long as no one really fucks it up that's ok.

php processes are always erring and dying in weird ways that no one can figure out, especially if anyone uses the half-baked OO stuff (circa 2008-9), and tracking down obscure php state errors ranges from difficult to impossible since you're never quite sure when or where something went wrong, but it works for most people most the time, as long as you remember to clear out the error logs so they don't get big enough to crash the box.

memory use still sucks at around 30M a process, meaning you can only have around 500 workers on at 16G RAM server, but it's workable. at least it's not rails.

because it takes a while to talk to even Memcache (go forbid you talk to MySQL) and do all your silly user updates (games are really write-heavy) you are taking a few hundred ms per request, so 16G mem servers (it's 2008) safely top out at around 500-600 req/sec, and i think would melt close to 1000 or so. remember, your throwing everything you have at growth and features so you're not really optimizing shit.

cool, just need more hardware. which is no problem. if you can get hardware. when you're co-located it takes forever to get new hardware online. not really an option. and even the F5 load balancers can only take so much. and there are issue with getting too many app servers talking to too many memcache servers. or something like that. after i left i think they saturated the data drops, which really puts you in a bind.

but that's not a problem now, with cloud services, right? except that those are not limitless either. i think FarmVille ran into a wall where AWS wouldn't / couldn't supply more instances (again, this was around 2009-10 so prob a lot better now). and those are still physical machines in physical datacenters somewhere that will have all the same problems and limitations and then some.

but you're going to have problems with any app runtime at that scale. and php's performance was an order-to-two or magnitude better than rails, and we never figured out how to get significantly complex and traffic-heavy java apps to stop leaking memory. though i'm sure you can. and you will! like i said, it's all solvable. hell, even MySpace didn't fail because of tech infrastructure.

what i'm saying is that php wasn't (and maybe still isn't?) particularly fun when throwing hardware at it doesn't work, and you end up losing a lot of the purity / simplicity of the model because it's too damn expensive. ffs, Facebook re-wrote the runtime. that's what it took for them. and my friends there tell me it's pretty much like writing java at this point. it's a fine choice, but i'd rather not use it again. had a much better time with python before javascript ate the world.

[dakull]

>php's performance was an order-to-two or magnitude better than rails

Again PHP (the language) vs. Rails (the framework).

What framework was that `big php app` using?

[chriswarbo]

> What framework was that `big php app` using?

PHP is a framework. True it's not a particularly nice one, and some people build even more layers on top, but it comes with all manner of HTTP/url/DB/etc. stuff out of the box. It's also a templating language (that's what the "<?php" tags are for); although, again, not particularly great, and some people layer more abstractions on top.

[bigtunacan]

In the sense of comparing PHP and Rails, then no PHP is not a framework. Codeignitor, Laraval, Cake, Yii; those are PHP frameworks and fair comparisons to Rails.

I can (and have) just grabbed Rack and rolled most everything myself in Ruby and it has way less overhead and is much more performant than Rails. Ruby also has it's own templating language; ERB is part of Ruby core.

So comparing PHP to Rails is a bit apples and oranges.

[nrser]

it's a business decision comparison, not a technical categorical comparison. you need something to receive http request and return http responses, and you're comparing different popular (because hiring, training, and available community / support resources) ways to do that. they might be apples and oranges but at that level you're concerned with comparing fruits.

[bigtunacan]

In this case it was a technical comparison; the original poster stated, "php's performance was an order-to-two or magnitude better than rails".

If you are making a technical comparison then it needs to be at the correct layer of abstraction. If we were to compare performance of Laraval and Rails that would be a fair comparison.

If we are comparing on performance then PHP should be probably be compared to Ruby+Rack since that is sort of the lowest common denominator.

I'm not dogging on PHP here either. Even comparing at the correct level; PHP is still faster, but lets make sure we are making the right comparisons.

[nrser]

i am the original poster.

i was clarifying the compassion.

[brightball]

Very true. It's basically an interface to a C framework.

[nrser]

as the other commenter said, php is a web framework... and it's what we were using. it's actually more of a web framework than a language in my opinion (or at least was at that point). it's centered around receiving http requests and writing http responses. the article mentions this in fact.

it was a huge pain to try and get php to do anything else. it was totally unpractical to do the kinds of back end processing that we needed (since the database was pretty much off limits during a http request)... long running processes with hundreds of millions of objects were a no-go. believe me, we tried. which meant you had to sync all your logic into Java or something else that could handle the job. which is really error prone when you have a bunch of people moving fast on something.

one of the greatest things about php is that it's a super minimal focused framework. it's also one of it's major short-comings when that model no longer suffices.

you can layer something else on top of it, but the stuff available at the time certainly didn't help the performance or memory characteristics.

[jliptzin]

I think I sat next to you at zynga back in 2008 and remember your php struggles vividly.

[nrser]

hey Josh!

[justinhj]

I feel your pain, I also worked on a large MMO style mobile game backend, but my situation was a lot better because as you say AWS is a lot more mature at this point.

Dealing with limited resources such as MySQL and Redis is a problem you still have to fix when you move away from PHP though.

As for the Facebook runtime, for us it was a case of drop in HHVM, fix a handful of issues and get a 4x or 6x speed increase for free. You only need to change the way you write if you move to Hack, but I think I agree with you that's probably getting to the limit of the effort reward tradeoff before you rewrite in a different language.

[niutech]

Why didn't you choose Python/Django instead of PHP then?