Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why Is JRuby Slow?

earthly.dev

Post reply on HN
Print view View original

21–30 of 64 posts

Re: Why Is JRuby Slow?

#21

Post by zizee »

nine_k wrote: post #16
zizee wrote: post #9

Earlier quoted context omitted.

Could you not make the same argument about JavaScript? JavaScript was pretty slow for many years. Google then put some significant engineering investment into the V8 engine, resulting in a huge increase in JavaScript's performance.

Of course the answer is positive. But it will take a drastic / complete rewrite of the VM, as it happened to Chrome's and Firefox's JavaScript VMs. This means many man-years, and a certain break in the continuity, maybe with small but noticeable deviation in the VM's behavior. If we squint just so, we can consider Ruby 3.0 to be such a rewrite. Crystal is a similar rewrite effort, but a one that isn't trying to stay…

For those of us with many man years of investment into existing Ruby systems, any further investment into speeding up the language's runtime and general evolution is welcome.

Re: Why Is JRuby Slow?

#22

Post by pjmlp »

djur wrote: post #15
cutler wrote: post #6

If you want fast Ruby it seems Crystal is your only option. Ruby is an interpreted language released in 1996 for scripting. Why are we surprised when attempts to shoe-horn it into something else (Ruby 3.0, JRuby, Truffle Ruby) fall flat?

Crystal isn't the "only option" for fast Ruby because it's not Ruby. If Crystal is an option, so are a lot of languages.

It is the option when syntax familiarity and similar language concepts count.

Re: Why Is JRuby Slow?

#23

Post by RcouF1uZ4gsC »

jshen wrote: post #12
tmp231 wrote: post #5

I remember about 10 years ago the promise was that JRuby was going to let ruby be basically as fast as Java for many things. Invokedynamic and all that.

It can be with work. This is basically true of all languages. I remember telling my team that I wanted them to use Java instead of python for some new service we were building because I wanted it to scale better. They were not happy about it, and they coded up two versions, one in python and one in Java. I was shocked by the results, they performed roughly equally in terms of latency and scaling. When I dug into it,…

> When I dug into it, the very abstract Java library that gave them the power of python ran about as fast as python. They could get rid of that library which made them far more productive, but then the project took longer and cost more.

Sounds like they were determined to write Python on Java. Doing it that way likely has a lot of performance costs. However, you can’t assume that idiomatic Java code would take that much longer than Python code for a team that was familiar with Java. Likely it comes down to which languages and frameworks a team is familiar with.

Re: Why Is JRuby Slow?

#24

Post by habibur »

Here's the summary: Ruby like most of all other Linux applications from that age was written to run in multi-process mode for parallelism, instead of being multi threaded.

But running multi-process is heavy on the JVM as it has to load the virtual machine and JIT for every process start, special when the processes are short lived.

Java solves it by encouraging running things as multi-threaded instead of multi-processed.

But Ruby wasn't built to run multi-threaded. And CRuby even if can run threads, does it by implementing a global thread lock. Aka, only one thread can run in a process at a time. The other threads have to wait until it finishes.

It looks like the multi-process implementation is good enough for CRuby and JRuby's attempt to turn it into multi threaded application didn't improve things.

Solution is to build a JVM that can load the virtual machine, JIT and execute applications fast enough like C programs.

Re: Why Is JRuby Slow?

#25

Post by [deleted] »

RcouF1uZ4gsC wrote: post #23
jshen wrote: post #12

Earlier quoted context omitted.

It can be with work. This is basically true of all languages. I remember telling my team that I wanted them to use Java instead of python for some new service we were building because I wanted it to scale better. They were not happy about it, and they coded up two versions, one in python and one in Java. I was shocked by the results, they performed roughly equally in terms of latency and scaling. When I dug into it,…

> When I dug into it, the very abstract Java library that gave them the power of python ran about as fast as python. They could get rid of that library which made them far more productive, but then the project took longer and cost more. Sounds like they were determined to write Python on Java. Doing it that way likely has a lot of performance costs. However, you can’t assume that idiomatic Java code would take that m…

[deleted]

Re: Why Is JRuby Slow?

#26

Post by lf-non »

jshen wrote: post #12
tmp231 wrote: post #5

I remember about 10 years ago the promise was that JRuby was going to let ruby be basically as fast as Java for many things. Invokedynamic and all that.

It can be with work. This is basically true of all languages. I remember telling my team that I wanted them to use Java instead of python for some new service we were building because I wanted it to scale better. They were not happy about it, and they coded up two versions, one in python and one in Java. I was shocked by the results, they performed roughly equally in terms of latency and scaling. When I dug into it,…

I am curious what library was this and what was it doing.

We used spring expression language for dynamic evaluation of (user-defined) expressions in our code and for most cases we could compile and cache the expressions after first usage and invoking them was really fast and close to pure java expressions.

We also had some JVM-python interop which we eventually got rid of (in favor of kotlin) because we were unable to optimize it after a month of effort and it continued to be the biggest bottleneck in the system.

So I am not entirely convinced that there could be real-world usage scenarios that inherently demands so much runtime dynamism that most benefits of JVM optimizations are nullified.

Of course, I'd love to be enlightened otherwise, but rather happy with JVM as of now.

Re: Why Is JRuby Slow?

#27

Post by bhaak »

joelbluminator wrote: post #19
jaredcwhite wrote: post #11

Earlier quoted context omitted.

Ruby's basically as fast as Node.js. If you look at comparative benchmarks, Roda/Rack/Puma is within spitting distance of Koa, Fastify, etc. Express is actually slower in some benchmarks. I don't think a lot of people are aware of just how much faster the Ruby ecosystem has gotten in the past few years (especially when you leave Rails out of the equation which is known not to do well in microbenchmarks).

I just heard Matz saying yesterday additional effort will be made to make Ruby run faster specifically on benchmarks. He said while they don't always correlate completely to real world performance, since developers seem to care a lot about benchmarks he wants Ruby devs to feel good about themselves and score well on these.

> he wants Ruby devs to feel good about themselves

We don't deserve Matz. He's too good to be true. :)

Re: Why Is JRuby Slow?

#28

Post by phibz »

I was surprised at the level of analysis and optimization here. Just running flame graph and saying "I think IO is slow" isn't going to cut it. Let's break out a profiler and dig in to the output. And also try some Java tools like your kit.

Re: Why Is JRuby Slow?

#29

Post by pjmlp »

habibur wrote: post #24

Here's the summary: Ruby like most of all other Linux applications from that age was written to run in multi-process mode for parallelism, instead of being multi threaded. But running multi-process is heavy on the JVM as it has to load the virtual machine and JIT for every process start, special when the processes are short lived. Java solves it by encouraging running things as multi-threaded instead of multi-process…

What makes GraalVM interesting is that it builds upon the research done in JikesRVM and MaximeVM, alongside a free beer offering.

Commercial versions of "a JVM that can load the virtual machine, JIT and execute applications fast enough like C programs" have been available since around 2000, like Excelsior JET or WebSphere Real Time JVM among others.

The JIT cache used in recent versions of Hotspot started as part of JRockit JVM, also commercial only product.

Re: Why Is JRuby Slow?

#30

Post by kaba0 »

lf-non wrote: post #26
jshen wrote: post #12

Earlier quoted context omitted.

It can be with work. This is basically true of all languages. I remember telling my team that I wanted them to use Java instead of python for some new service we were building because I wanted it to scale better. They were not happy about it, and they coded up two versions, one in python and one in Java. I was shocked by the results, they performed roughly equally in terms of latency and scaling. When I dug into it,…

I am curious what library was this and what was it doing. We used spring expression language for dynamic evaluation of (user-defined) expressions in our code and for most cases we could compile and cache the expressions after first usage and invoking them was really fast and close to pure java expressions. We also had some JVM-python interop which we eventually got rid of (in favor of kotlin) because we were unable t…

There is nothing at the JVM level that would disallow such dynamism. Clojure, JRuby, JPython all can run on the JVM.

Also, if you are looking for interop, then GraalVM might be worth a look — not the better-known AOT part, but the runtime one, which can seamlessly do interop between a number of languages, and it even optimizes between them!

Post reply on HN