split: init replica lb splitter with global rand#94754
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craig[bot] merged 1 commit intocockroachdb:masterfrom Jan 5, 2023
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split: init replica lb splitter with global rand#94754craig[bot] merged 1 commit intocockroachdb:masterfrom
craig[bot] merged 1 commit intocockroachdb:masterfrom
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erikgrinaker
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I'm assuming the default source is seeded here?
Lines 54 to 55 in 9351196
In cockroachdb#93838 we started initializing a new seeded rand for use in the load based splitter's reservoir sampling algorithm. Previously, the splitter was initialized using the global rand. `rand.Source` heap allocates on init approximately 4kb. When initialized per-replica, this is problematic as nodes scale to large replica counts. This patch replaces initializing a new random source per-replica with using the global rand instead. resolves: cockroachdb#94752 resolves: cockroachdb#94737 Release note: None
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Yeah - perhaps a misleading title/commit msg. I've updated it to be more specific. |
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bors r=erikgrinaker TYFTR |
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In #93838 we started initializing a new seeded rand for use in the load
based splitter's reservoir sampling algorithm. Previously, the splitter
was initialized using the global rand.
rand.Sourceheap allocates on init approximately 4kb. When initializedper-replica, this is problematic as nodes scale to large replica counts.
This patch replaces initializing a new random source per-replica with
using the global rand instead.
This removes the heap allocation. This is shown below running
kv/splits/nodes=3/quiesce=true(not at identical replica counts in the test,the proportions are the important part).
before:
after:
resolves: #94752
resolves: #94737
Release note: None