Re:Open-sourcing a 10x reduction in Apache Cassandra tail la...
by sreque on Tuesday March 06, 2018 @01:08PM
(#16530648)
You're right on your first point. I responded a little harshly to OP because I believe they responded too harshly to the blog post. The P99 GC latency data they give is us not sufficient to explain their perf gains. More likely, the metric they were tracking was well-correlated with their perf gains, but not the only or even primary cause. The other perf gains could have been caused by reduction in older generation collection times, for instance.
Re:Open-sourcing a 10x reduction in Apache Cassandra tail la...
by eptcyka on Tuesday March 06, 2018 @07:16AM
(#16528342)
I'd love to see how Go's GC performs when running an application similar to Cassandra, on multiple cores, with gigabytes of memory allocated.
Re:Open-sourcing a 10x reduction in Apache Cassandra tail la...
by the8472 on Tuesday March 06, 2018 @02:58PM
(#16531565)
Go's GC is non-moving, incremental and single-generation. Hotspot GCs are all moving collectors so they make different tradeoffs.
IBM's metronome collector would be the closest one to Go's properties.
Re:Open-sourcing a 10x reduction in Apache Cassandra tail la...
by b4lancesh33t on Tuesday March 06, 2018 @07:41AM
(#16528426)
This is a thing others have already done, although I don't have citations to hand.
That is not a given. And, even distribution is only part of the equation. If they are sufficiently short, then even being somewhat unevenly distributed should not have much of an impact on latency. For example, if the max length of a pause were 1ms, and 99p latency were 15ms, you'd have to be fairly unlucky to see a 33% increase in latency99 due to GC. That would entail 5 of 25 pauses happening during a 20ms period in a 1s window.
(This idea is not purely hypothetical. For example, Go's GC has very low STW periods.)
> It's pretty much accepted everywhere
Eh. Apparently everyone thinks C is the best language for cryptography and other secure but not particularly perf sensitive code. Go figure. Sometimes the wisdom of the masses is not wisdom. Best not to appeal to it during argumentation.