A single line of code made a 24-core server slower than a laptop

Re:A single line of code made a 24-core server slower than a... by dagmx on Friday December 31, 2021 @01:17PM (#29750811)

Edit: another comment explains that you're likely talking about just the ref counting aspect rather than the entire context sharing used by the rune code shown, in which case, yes I see why a concurrent GC would avoid the issue in that scenario.

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I'm familiar with Go's GC. Your linked post doesn't explain how it would avoid the hit mentioned by the cache invalidation across multiple clusters.

It'll either try and put multiple go routines on a single cluster (as listed in the link) or it'll need to copy the necessary stack per thread. Which is effectively what the original article ends up doing.

But if you encounter anything that needs to run concurrently across threads while using a single r/w object, you'll hit the same cliff surely?

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Re:A single line of code made a 24-core server slower than a... by YogurtFiend on Friday December 31, 2021 @02:00PM (#29751274)

While this isn't true with Go's GC, a GC that's stop-the-world can avoid these cache coherency issues altogether. If you pause every thread before marking and sweeping, then you won't run into problems--only the GC is running. While this may sound silly, stopping the world will oftentimes lead to higher throughput than concurrent collectors, at the cost of higher latency (which is why it's not suitable for Go, which is often used for building servers where latency is a priority).

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