Why is Arrays.fill 265 times slower on G1GC?

(krzysztofslusarski.github.io)

19 points by ejboy3 days ago

3 comments

hyperpape1 hour ago
I'm genuinely curious about the effect, but I simply don't have patience for the AI writing. Can anyone give an actual non-garbage explanation with some respect for the reader?Slightly less annoying summary from ChatGPT free: <a href="https://chatgpt.com/share/6a9ac7a3-15a0-83eb-8c2a-6f72cd9bebad" rel="nofollow">https://chatgpt.com/share/6a9ac7a3-15a0-83eb-8c2a-6f72cd9beb...</a>.Caveat emptor: it makes high level sense, but I haven’t thought about it in detail.
- marcianx1 hour ago
 I'm genuinely curious: I read through the article and the narrative felt deliberate and didn't trigger my AI-radar. What made you think it was AI written?
 - anon4829351 minutes ago
 It didn’t read AI generated to me. I also love the irony of then using AI to generate a summary
 - hyperpape48 minutes ago
 > This article is the story of chasing that number down to a single machine instruction, and then finding out that the instruction was only half of the answer.> So the difference has to be in what the JIT generated, and the profiler gives us exactly that.> That is the whole vocabulary. Let’s read some code.> Decoding the x86 version instruction by instruction is out of scope here.> What is not architecture specific is the logic.Here’s a segment flagged by Pangram: <a href="https://www.pangram.com/history/87e25169-30a4-4030-a65a-dba8a19c6769?ucc=z1d80G4Q5BH" rel="nofollow">https://www.pangram.com/history/87e25169-30a4-4030-a65a-dba8...</a>
 - anamexis25 minutes ago
 I don't know if it's AI or not, but if it is, it isn't egregious, and certainly not "garbage" or disrespectful to the reader.
 - xpct9 minutes ago
 I don't think the Pangram result is shareable to others."If you are sure the link is correct, please make sure you are logged in with the account associated with this result."
 - Capricorn24813 minutes ago
 Even if that were AI (and I think there are better examples in the article to indicate that it is), why do you care if you just used AI anyway to summarize it anyway?
 - ramchip11 minutes ago
 [dead]
pron45 minutes ago
There are two practical lessons here:1. Upgrade your JDK for the best performance (as the article says, the slowdown is gone in JDK 26).2. Don't try to help the GC by pooling objects. Mutating old objects can be expensive, while allocating new ones is cheap (at least for objects that don't do some exceptionally expensive initialisation).