4.x: parallel performs poorly with 10+ parallelism
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@akarnokd is already working on this.
Since Mar 11, 2020.
4.x
Performance
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Description
For some reason, the parallel Scrabble benchmark performs poorly when the parallelism level is 10+, for example, on my i7 8700 CPU (6 cores/12 threads):
However, my older i7 4770K processor (4 cores/8 threads) shows no such performance degradation. Neither does the reactive-streams-commons implementation (the parent of RxJava's parallel implementation) with parallelism=12.
Correction: The Rsc benchmark was pinned to 8 threads and actually shows a similar inefficiency with 10+.
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