Huang Kuan Hao created HDDS-16310:
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Summary: Avoid allocating a comparator per HeapEntry comparison in
ListIterator
Key: HDDS-16310
URL: https://issues.apache.org/jira/browse/HDDS-16310
Project: Apache Ozone
Issue Type: Improvement
Reporter: Huang Kuan Hao
Assignee: Huang Kuan Hao
ListIterator.HeapEntry.compareTo builds a new composed Comparator on every
call. It backs the PriorityQueue<HeapEntry> min-heap that merges the cache and
table iterators for listStatus, so draining a listing of N entries allocates a
fresh comparator (2-3 short-lived objects) on each of the O(N log N)
comparisons.
Current:
public int compareTo(HeapEntry other) {
return Comparator.comparing(HeapEntry::getKey)
.thenComparing(HeapEntry::getEntryIteratorId).compare(this, other);
}
Fix: hoist to a private static final Comparator<HeapEntry>, using
thenComparingInt for the int secondary key. Behavior unchanged.
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