Chromium Blog: A New Crankshaft for V8

http://blog.chromium.org/2010/12/new-crankshaft-for-v8.html

by twapi • 16 years ago

242 90 16 years ago

blog.chromium.org

greattypo• 16 years ago

The Chrome javascript engine team is simply a beast.

CJefferson• 16 years ago

Has anyone got any experience using javascript/V8 as a scripting language for a C++ app? We currently use python with boost::python bindings, but are finding we have to limit the amount of python code, as it is too slow.

tlb• 16 years ago

At Anybots, we built all the real-time robot code in Python with performance-critical bits in C++ wrapped using boost::python. Server code is in pure Javascript on Node.JS. I haven't tried to integrate C++ into Node, but it looks easy.

kqr2• 16 years ago

Have you looked into lua? It's a good embedded scripting language.

http://www.lua.org/

pygy_2• 16 years ago

Especially, for x86 and x64, where you can use LuaJIT.

LuaJIT2 is still in beta, but it is already very stable. Performance-wise, it is comparable to Haskell and Java.

http://luajit.org/

pjscott• 16 years ago

Also, the language itself is pleasant and straightforward. If you know other modern programming languages, Lua shouldn't be too surprising.

DanielRibeiro• 16 years ago

Ever looked into Cython? http://www.cython.org/

Sage (a open source replacement for matlab) uses it quite successfully for speeding up critical paths.

russell_h• 16 years ago

Thats essentially what Node.js is, although with a heavy focus on asynchronous operation.

Check out: https://www.cloudkick.com/blog/2010/aug/23/writing-nodejs-na...

azakai• 16 years ago

Syntensity moved from Python to JavaScript as an embedded scripting language,

http://www.syntensity.com/toplevel/intensityengine/

worked out very well there.

Of course the real examples are... web browsers, which are C++ apps that are scripted by a JavaScript engine. Seems to work good there as well ;)

ashot• 16 years ago

unreal. how much theoretical headroom is left to optimize js compiler performance?

I had assumed we were reaching some theoretical upper-bound because all major frameworks were on par in terms of performance.

jerf2• 16 years ago

To a first approximation, my answer would be something like http://shootout.alioth.debian.org/u32/benchmark.php?test=all... .

That's not necessarily the whole answer and I imagine JS can't ever quite go that fast. But still....

Raphael_Amiard• 16 years ago

> and I imagine JS can't ever quite go that fast

I'm not the most knowledgeable person on the subject, but from what i understand, there is no theoretical reason that JS couldn't go that fast. The two languages are more similar than they are different, even if JavaScript is quite more complex.

I remember Mike Pall saying something similar in an LTU thread some time ago.

SwellJoe• 16 years ago

Would this imply that Lua has reached some pinnacle of speed and can't go any faster? That seems to be a side effect of your statement.

I'm not familiar with Lua, beyond reading an article or two about it, but does its simplicity imply some sort of maximal efficiency? Are the developers behind Lua simply the best programmers in the world and already have everything figured out with regard to optimizing a JIT? I'm not arguing with you...it does seem like that's a reasonable goal for JavaScript JITs to strive for in the near future. But, it doesn't really answer the question of how much better performance can get (in JavaScript or Lua or any other language). Past performance is not necessarily indicative of future performance when so many people are working on the problem from so many angles.

kragen• 16 years ago

I think http://shootout.alioth.debian.org/u32/benchmark.php?test=all... is probably a better ceiling. LuaJIT is fantastic and already generates better code than GCC in some cases, but in many others it does not.

There's no theoretical limit to how close a compiler can come to a programmer when it comes to generating machine code to do a particular well-defined task.

seanalltogether• 16 years ago

Javascript execution is very rarely the bottleneck on webpages. The bottleneck is almost 90% render speed of dom updates.

thasmin• 16 years ago

When Chrome was released two years ago, I noticed a significant difference in speed. Nowadays I think the announcements JavaScript performance improvements is a bit overenthusiastic. The only real world benchmark mentioned in the article is that Gmail loads 12% faster. What JavaScript apps are constrained by performance and what are Crankshaft's effects on them?

pohl2• 16 years ago

I'm happy that the various javascript teams are developing towards where the web is going rather than where it is.

"A good hockey player plays where the puck is. A great hockey player plays where the puck is going to be." — Wayne Gretzky

timtadh• 16 years ago

I don't think the GP would disagree with you. I believe he was asking what specific apps benefit today (besides GMail which was mentioned in the blog).

johnthedebs• 16 years ago

I think the point of these optimizations is that they allow javascript-intensive applications to be developed that would otherwise have just been too slow.

In other words, they're paving the way for the future more so than trying to squeeze every last ounce of speed from current applications (which just happens to be a great side effect of their work).

jamesaguilar• 16 years ago

Yeah, you won't see a lot of applications that benefit from these optimizations immediately because if there were any that would mean that they had been written before there was any device capable of running them.

InclinedPlane• 16 years ago

Much web client JS is constrained by dom speed so this will only have an incremental effect. However, for node apps this willbe pretty significant.

pornel2• 16 years ago

> What JavaScript apps are constrained by performance and what are Crankshaft's effects on them?

Canvas and WebGL games.

Splines2• 16 years ago

So - how long does it take for features to make their way into production? Am I reading the release calendar correctly in that it'll take 12 weeks from start of development to beta, and another 12 weeks from beta to stable?

It looks like Chrome 8 went stable on 12/2. So we'll see Chrome 10 in 4 months?

aboodman2• 16 years ago

Chrome stable releases are every 6 weeks.

The releases are overlapped though, so we are testing v n+1 in beta while v n is in stable, and we are starting new feature development for v n+2 while v n is in stable.

Chrome 8 just went stable, and we've just started testing Chrome 9.

So crankshaft will either be 6 weeks from today (if it's in 9), or 12 weeks from now (if it's in 10).

I don't think it's been announced which it's targeted for.

HTH

Splines2• 16 years ago

Ah, ok. I guess I misread the release calendar. Thanks for the clarification :).

> I don't think it's been announced which it's targeted for.

According to the perf comparison chart on the blog, it's in Chrome 10. Also, it's mentioned that Crankshaft is available in the canary build, which is currently at 10 too.

12 weeks then. I sometimes revert back to FF for the plugins, but I always come back to Chrome for the perf :).

kenjackson3• 16 years ago

I'm curious to see if they broke any code, like the IE engine did recently. For example, with loop-invariant code motion, what is legal in a language like C, may not be in Javascript (for same reason the IE DCE optimization was invalid).

I'd find it hard to believe that Goog would make the same mistake after all the hullaballoo, but I'd love to see it validated.

pbiggar3• 16 years ago

Loop-invariant code motion is still legal in JS, and most dynamic languages, as is DCE. You just need to take into account the weird semantics of JS.

What the IE team got wrong was the assumptions they made about the semantics of the code that was optimized. If they had checked for the presence of a valueOf property, they could still have done the optimization.

kenjackson3• 16 years ago

Exactly. I'm not saying those opts aren't legal, but in cases that look legal in C, they're not legal in JS. And note, you can still do it in the presence of a custom valueOf method, as long as it doesn't have side effects (and thus of course loop-invariant itself).

In essence I'm asking if Google does in fact do this check, and does analysis to ensure that the valueOf method doesn't get written dynamically in the loop itself.

VMG• 16 years ago

I'd like to have a guide for writing code that is easily optimized by V8 and similar engines. Having local variables is good, as far as I can tell, but it would be nice to have a full overview with dos and don'ts

drivebyacct23• 16 years ago

"Having local variables is good"

Reading sentences like this scare me because it reminds me that some people don't know what the 'var' keyword means or think it's acceptable to shove everything in window or global.

alanh• 16 years ago

The IE team didn’t break anything in shipping software, right? This is just an IE9 beta problem, presumably fixable before they ship a stable IE9?

kenjackson3• 16 years ago

Absolutely. It wasn't even beta, it was just a tech preview. If they didn't have bugs of that sort, they aren't pushing things hard enough.

todd3834• 16 years ago

Will this have any effect on NodeJS?

jrockway• 16 years ago

Seems like it should.

tlrobinson• 16 years ago

Sure, I would expect node.js to be an ideal environment for this type of hot code analysis, since servers written with it are typically long running vs. more transient web pages. Of course whether there are significant gains depends a lot on whether your server is CPU-bound or IO-bound.

mxavier• 16 years ago

This seems like it would be huge for the Node.js people. The next big milestone for V8 for node has to be the GC issues that have been wreaking havoc on node apps under high load.

chrislloyd• 16 years ago

I doubt it.

From what I understand, the significant improvements in speed come from Crankshafts tradeoff of compilation optimisation for startup speed. If your app is a for loop with 2 iterations that code path won't be heavily optimised as the interpreter would potentially be more spending more time compilation code than in execution of unoptimised code. It will therefore startup faster. However, hotspots (loops with 1,000 iterations, per se) will be heavily optimised.

This is great for websites as speed and responsiveness is perceived as startup time. You'll certainly notice a difference when using the Node as a scripting tool. However, most Node applications are long running servers executing the same code paths over and over. Its unlikely that Crankshaft is performing any extra optimisations, it is just changing when it performs these optimisations. However, if Crankshaft _is_ doing significantly more advanced optimisations (I don't know) then, yes, Node will benefit. Please correct me if I am wrong, I would love to be.

nene• 16 years ago

From the article:

> In addition to improving peak performance as measured by the V8 benchmark suite, Crankshaft also improves the start-up time of web applications such as GMail.

As I understand it, there is more to Crankshaft than just startup time improvement.

cwp• 16 years ago

Node-based servers will definitely benefit from this. The advantage of a two-stage compilation scheme is that the "base" compiler generates non-optimized code that is self-profiling: it collects type information as it runs. That information is then used by the second-stage compiler to produce code that is more optimized than a single-stage compiler (like pre-Crankshaft V8) can produce.

swannodette• 16 years ago

It will be interesting to see how this optimization affects V8's memory profile (and how that in turn affects the currently slim memory profile of Node.js).

dtwwtd• 16 years ago

It will also be interesting to see if this improves performance of long running Node.js scripts.

panarky• 16 years ago

Looks like this Node patch includes Crankshaft: https://github.com/ry/node/commit/c30f1137121315b0d3641af6dc...

natmaster• 16 years ago

"...performance of JavaScript property accesses, arithmetic operations, tight loops..."

Does this mean Crankshaft includes a tracing JIT like Firefox? This layman speak confuses me.

scott_s2• 16 years ago

Yes, look at the list of the four main components.

pbiggar3• 16 years ago

I don't think that says it uses a tracing compiler (naturally the terms are vague in this field, so I'm not certain). Their architecture looks much more like HotSpot than TraceMonkey.

cosgroveb• 16 years ago

Gmail really does seem to load in about half the time now in the Canary build.

ams61102• 16 years ago

OTOH this does not bode well for the future potential bloat in Gmail.

StuffMaster• 16 years ago

Sounds like they borrowed the tracing idea from mozilla.

scott_s2• 16 years ago

Not really. It's a well-known VM optimization technique.

cpr• 16 years ago

First featured in Self many years ago, done by the same folks (Lars Bak and crew) who brought you V8. Then Sun bought their Smalltalk/Self-based company, and they built HotSpot for the JVM. Then Google hired them to do the same for Javascript, and now we have V8.

It generally takes about 10-20 years to get truly new ideas from the labs to consumer-level products.

grayrest3• 16 years ago

They don't mention that they're tracing. I think they're just optimistically optimizing functions in hot loops.

erik_landerholm• 16 years ago

I thought someone was actually developing a new kind of crankshaft for a real V8 engine....

eru3• 16 years ago

Doesn't `Chromium Blog' and the URL give it away?

_urga• 16 years ago

Next up, remove the 1.9GB max memory limit of V8 processes: http://code.google.com/p/v8/issues/detail?id=847

tsta• 16 years ago

I've benchmarked Google Chrome 9.0.597.10 and 10.0.603.3 (with Crankshaft) and the latter is 30% faster. See the detailed results: http://dromaeo.com/?id=124912,124913

Chromium Blog: A New Crankshaft for V8

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