As long as we are recapitulating history - the main reason we built a new multiprocess architecture is that Chromium's multiprocess support was never contributed to the WebKit project. It has always lived in the separate Chromium tree, making it pretty hard to use for non-Chrome purposes.
Before we wrote a single line of what would become WebKit2 we directly asked Google folks if they would be willing to contribute their multiprocess support back to WebKit, so that we could build on it. They said no.
At that point, our choices were to do a hostile fork of Chromium into the WebKit tree, write our own process model, or live with being single-process forever. (At the time, there wasn't really an API-stable layer of the Chromium stack that packaged the process support.)
Writing our own seemed like the least bad approach.
If Google had upstreamed their multiprocess support, we almost surely would have built on it. And history might have turned out differently.
I'd also add that I disagree with Mike about the architectures being really different. In fact, they are quite similar in broad strokes, but with many differences in details (and with the significant difference that the Chromium model isn't in WebKit per se).
I don't understand this claim. WebKit2 was landed with effectively no notice and no attempts at collaboration. I saw repeated attempts to work on a shared architecture in WebKit2, but none were reciprocated. http://goo.gl/KH1Sr Eventually all non-Apple contributors were cut off entirely from WebKit2 as a matter of policy. http://goo.gl/iTDAR
>We talked privately with particular Chrome folks before we started (as described upthread), in the middle, and shortly before landing to mention that we were landing soon.
Yes, I'm aware of that, but the work had been underway for a long time and was about to be dropped by the time there was a real heads up. So the core of the architecture was already being frozen from a larger perspective.
>BTW I am not trying to pick a fight here. I think mikewest's comment gave the impression that Apple built a multiprocess architecture out of cussedness or NIH. But that's not how it was.
I don't interpret Mike's comments that way. Chromium's architecture was public and available, but we assumed it wasn't used because it didn't fit the needs of WebKit2. There's no malice in that. We designed Chromium from the beginning for SFI (as Adam tried to convey), and that incurs quite a bit of complexity. I'm comfortable that the divergence was simply a result of different needs. I just don't see how it could be presented as something malicious or anti-collaborative.
>> We talked privately with particular Chrome folks before we started (as described upthread), in the middle, and shortly before landing to mention that we were landing soon.
> Yes, I'm aware of that, but the work had been underway for a long time and was about to be dropped by the time there was a real heads up. So the core of the architecture was already being frozen from a larger perspective.
Are you aware of the earlier conversation that occurred before we wrote any lines of code or even had a name? Where we talked about the possibility of just using Chromium's model if Google was willing to contribute it back? I have mentioned it twice - maybe you overlooked those parts of my remarks.
> Chromium's architecture was public and available, but we assumed it wasn't used because it didn't fit the needs of WebKit2. There's no malice in that. We designed Chromium from the beginning for SFI (as Adam tried to convey), and that incurs quite a bit of complexity.
It had nothing to do with SFI (which wasn't brought up at the time) or complexity. It was for the reasons I stated upthread.
>Are you aware of the earlier conversation that occurred before we wrote any lines of code or even had a name? Where we talked about the possibility of just using Chromium's model if Google was willing to contribute it back? I have mentioned it twice - maybe you overlooked those parts of my remarks.
The Chromium code is all in a public repository and was already integrated into WebKit via Chrome's platform layer. Members of the Chrome team were also interested in helping better incorporate Chrome's model into WebKit. So, I must be misunderstanding you, because it seems like you're suggesting that you expected Chrome engineers to simply do all the work.
>It had nothing to do with SFI (which wasn't brought up at the time) or complexity. It was for the reasons I stated upthread.
I still don't get what that reason is supposed to be. Regardless, the resulting WebKit2 design was clearly incompatible with the existing Chrome architecture. And the fact that they were continuing to diverge and place a burden on both projects was a clear problem. This was raised repeatedly, but never seemed to receive any serious consideration.
My interest in this thread was only to report on some history that I knew about personally, to correct what I thought was an incomplete version of events. I think a bunch of people found that information useful and interesting.
I regret that this thread has turned into such a back-and-forth. It's not my goal to detract from the Blink announcement. I feel like it would be rude to leave you hanging on mid-thread. However, I feel like:
(a) You are trying to argue with my version of specific events where I was present in person and you (as far as I recall) were not.
(b) You are trying to argue with my stated motivations for decisions that I was part of and you were not.
(c) You seem to want to assign blame.
Maybe my impressions are wrong. But given this, I find it hard to reply in a way that would be constructive and would not further escalate. I hope you will forgive me for not debating about it further.
Yeah, I didn't intend this to turn into a back and forth. I think we both had similar intentions, but from different perspectives and with different first-hand information that may not be well communicated. I agree that it's best to leave it be from here. I think both of us and our respective projects bear no ill will and desire the best for the Web as a whole, despite differences in how exactly to get there.
A request for clarification on why they refused was posed to a Chrome engineer in todays Blink Q&A (http://www.youtube.com/watch?v=TlJob8K_OwE#t=13m34s), and according to him the request for integration came shortly after Chrome was released, and the reason for their refusal was the sheer scale/complexity of the task.
In light of this, your initial "if Google had only upstreamed their multiprocess support...we almost surely" and reiterations on this point within the thread do seem a bit like PR sleight of hand, since out of context it implies willingness to do so was the only issue on their part.
1) The answer wasn't "we'd like to do this but we're super busy right now, how about later" or "that's super complicated, will you guys put in a lot of the effort". It was a pretty direct no. We would have been willing to do much of the work.
2) My recollection is that we talked about it around a year after Chrome was released.
Chrome Beta release date: September 2, 2008
Date of WebKit2 announcement: Thu Apr 8, 2010 (after <1 year of development)
I don't have records of the meetings where we walked though.
3) Does the reason for saying no affect whether our choice to make our own thing was reasonable?
With regards to 3), yes it does affect it since a "flexible/malleable no" is an altogether different constraint from a "solid no", so the solution would be measured against a different yardstick in the former case. Pressing on with your own thing in the interests of time to market (and thereby further cementing the more mature implementation not being integrated) in that scenario does strike me as less than ideal/short-sighted.
This is somewhat moot with 1) and 2) being the case (or at the very least strongly perceived to be the case on your side). At any rate neither side being able to settle on a single version of events signals a communication problem, which makes the whole value of this hypothetical joint undertaking fuzzy anyway.
Hi Maciej. Sorry if my comments read as though I was implying that you were wrong or bullheaded to choose WebKit2. That wasn't my intention; there are of course good technical arguments for choosing either architecture, and I'll choose my words more carefully next time the question comes up.
I'm no stranger to open source, but can you please explain what a "hostile fork" is? Especially in this context, it just seems like diction for the sole purpose of making Google look like they were 'in the wrong' in that situation.
If we took Chromium's multiprocess code and put it in the WebKit tree after the Chrome folks specifically said they did not want to do that, that would have been super rude. Don't you think? That's why I say "hostile fork". I am judging our own path not chosen, and do not mean to cast aspersions on Google's actions.
To be clear, I do not consider Blink to be a hostile fork. I wish the Blink developers good luck & godspeed.
A hostile fork is one done unilaterally, generally without consultation or the blessing of the main project. It generally causes acrimony and community fragmentation, and usually no code changes are shared between the forks after the split.
Compare to forking to solve a very specific or specialized problem that doesn't make sense to merge upstream, like a set of changes that only apply to a very narrow audience or esoteric use-case. In such a case, it's common that changes that do affect the main project are still merged upstream and special care is done to make sure the forks don't diverge too much.