[throwaway34241]

Based on the facts stated in the article (part 2), it looks like (years later) Java now has a new garbage collector available (ZGC, still labeled experimental, not used by default) [1]. It's an order of magnitude lower latency than current default collector, but it still has an order of magnitude higher latency target (10ms vs 1ms) than Go. I'm sure there are many good reasons for the trade offs made and that's a huge improvement, but in light of the basic numbers I'm not sure that "the Java guys are winning the low latency game" is, in fact, a fair conclusion.

Go introduced a new GC a while back with dramatically lower latency numbers, not only compared to the previous Go GC but any other commonly available GC in any language (excluding exotic commercial ones like Azul). Neither the old or new Go GCs are particularly sophisticated compared to the highly developed ones in the Java ecosystem.

The author of these articles seems to take objection that the latency numbers were achieved not by magic or pure GC implementation genius but by simply optimizing for latency, which involves some trade offs. I don't think this negates the usefulness of having a low latency GC available though, although I can understand how it might be frustrating to see a project getting a lot of attention for what feels like a lesser intellectual achievement.

Obviously not all projects even require low worst-case latency, monolithic apps will be less sensitive, applications waiting on 10 other services will be more etc. Some apps the CPU isn't a bottleneck either. It's just another trade off where Go is prioritizing some things. There's even other factors not mentioned in the article like a compacting collector might make calling C functions more complex since it needs object pinning.

[1] There's also another GC mentioned that's less talked about in the article, Shenandoah, that requires patching the JVM and introduces memory overhead to every object for a forwarding pointer. It was hard to find numbers, but it looks like the latency target for this GC is also in the 10ms range (http://clojure-goes-fast.com/blog/shenandoah-in-production/).

[denulu]

> It's an order of magnitude lower latency than current default collector

Believe it or not, the current default GC is G1GC, which has a target (and quite common) pause of 300ms by default.

> Go introduced a new GC a while back with dramatically lower latency numbers

Or maybe just like Azul's numbers from 2005?

http://big-elephants.com/2018-09/unexpected-gc-pauses/

https://www.usenix.net/legacy/events/vee05/full_papers/p46-c...

> Shenandoah, that requires patching the JVM

The page you linked to says "How do you get Shenandoah? This garbage collector has officially become part of JDK only since version 12 and is available in AdoptOpenJDK 12 builds."

> and introduces memory overhead to every object for a forwarding pointer.

The first version did, Shenandoah 2.0 does not

https://shipilev.net/talks/jugbb-Sep2019-shenandoah.pdf

[throwaway34241]

> Or maybe just like Azul's numbers from 2005?

In the very sentence you quoted I said “excluding exotic commercial ones like Azul“. I’m not sure what point you are trying to make here.

> Shenandoah 2.0 does not

I see. I only googled that link to find the latency target (since it wasn’t mentioned in the original article), I have to confess I didn’t read the rest of it and almost all of what I wrote is based on the original article. Good to know that some of that information is now out of date.