Traversers start at the start and are recycled #3268
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tommesic
reviewed
Aug 7, 2025
| for (Node<K, V> p; (p = t.advance()) != null;) { | ||
| boolean exhausted = false; | ||
| try { | ||
| for (Node<K, V> p; (p = t.advance()) != null; ) { |
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Does this always skip/advance past the table 0 if 't' happens to be the one that was just instantiated above?
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No, traverser start "before" the first entry, so successive calls to advance every entry in sequence.
tmesic99
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Aug 13, 2025
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Prevent hash 'clumping' where unevenness in table slot usage can be exacerbated by the fact that we sample uniformly through the table, but not through the table usage when creating a traverser for selecting our eviction sample. This leads to slots in low density areas having a higher chance of being evicted, therefore leading to increased clumping. To prevent this we start traversers at the start of the table and then recycle them for subsequent evictions as they are exhausted. This ensures every slot has an equal chance of being selected for eviction.