Thomas Würthinger is a JVM hero | Hacker News Reader

Thomas Würthinger is a JVM hero

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34 pointscarsongross14 comments

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How about "A fully hotswappable JVM - never restart again"?

Also, VMs in the Smalltalk family have been doing this for a long time.

Sure. But JVMs haven't. (Unless you paid for something like JRebel, which has its own issues.)

Thomas is a genius and extremely nice to boot. He deserves to be more widely known.

Ah, yes. I meant to include that in my comment but I was on my mobile phone and too lazy.

Both could have been included in the headline, though.

I have tried many times to get JRebel to work properly. So, I gave up as the docs are horrible. It (JRebel) uses an agent to do the hot swapping instead of modifying the jvm.

I grabbed DECVM (and unfortunately I had to grab ICED Tea to run it on OS X, so this limits my use) and it works wonderfully so far. The only thing that JRebel does offer, that perhaps some of us will figure out for DECVM, is reloading Spring configurations. Since a lot of us are using DI, the DECVM tool only gets us to point, then the wonderful JVM restart has to happen.

Smalltalk is not statically typed, which I guess makes hotswapping a lot easier.

It's also a miniscule part of the market.

So you mean simplicity actually makes a lot of features easier? No shit :)

I don't see what market share has to do with the issue at all.

Interesting.

While from a code licensing perspective there's no trouble with OpenJDK forks, the patent licensing supposedly only holds for implementations that can pass the compatibility kit, which Oracle has refused to let alternate JDKs run in the past. I wonder if they have changed their tune for this or if they are just looking the other way.

That is an interesting point . . . OpenJDK itself is covered by the patent grants, but this is a patched version of OpenJDK. That said, the original research done here was sponsored by Oracle, and Thomas now works in Oracle Labs.

Pardon the off-topic complaint, but why on earth would anyone put ads on a company developer blog? Isn't the business rationale for a blog like this to advertise the technical prowess of the company? In that case, is the ad money really worth significantly cheapening the experience of reading the blog?

The ads were put there by wordpress, which we use to host the development blog; we're not so immensely retarded that we'd explicitly put them on ourselves to try to make money. Until recently (today? this week?) they've never been there, so we didn't notice them or think to purchase the ad-free version. As soon as someone on our team noticed this (about 5 minutes ago), we purchased the no-ads upgrade.

we're not so immensely retarded that we'd explicitly put them on ourselves to try to make money

That's a relief. :P

I'll grudgingly admit I could have been a little more charitable in my assumptions.

Still gotta fix GC fragmentation before I'll never have to restart my JVMs.

Well, for development anyway... It is amazing.

Yeah, never isn't a likely timeframe for JVM restarts, especially in development, where the DCEVM really shines. You change some Java class, you have your Tomcat server running, you get your new behavior on your web app that you can test out right away without restarting Tomcat. It is a huge productivity boost.

I'm not convinced that you'd want to use DCEVM in production.

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