[CASSANDRA-21359][trunk] Reduce allocation in row merge logic#4795
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netudima wants to merge 1 commit into
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[CASSANDRA-21359][trunk] Reduce allocation in row merge logic#4795netudima wants to merge 1 commit into
netudima wants to merge 1 commit into
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org.apache.cassandra.utils.MergeIterator.Candidate - has Comparator field which is the same for all Candidates under an MergeIterator instance, we can move the field to MergeIterator level. Candidate is 4.8% of all allocations and we can save 20% (~1% of all allocations) of it for JDK 21 with compressed references on. switch from ArrayList to array in org.apache.cassandra.db.rows.Row.Merger The ArrayList iterator costs 0.72% and BulkIterator.Adapter costs 0.35%. So, in total we can save here ~1% of total allocations. patch by Dmitry Konstantinov; reviewed by TBD for CASSANDRA-21359
frankgh
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May 12, 2026
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Looks good in general, I just a small comment
| } | ||
| // try to estimate and set a potential target capacity | ||
| if (dataBuffer.length < columnsCountEstimation) | ||
| dataBuffer = Arrays.copyOf(dataBuffer, columnsCountEstimation); |
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Any reason why we don't directly do ?
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| dataBuffer = Arrays.copyOf(dataBuffer, columnsCountEstimation); | |
| dataBuffer = new ColumnData[columnsCountEstimation]; |
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org.apache.cassandra.utils.MergeIterator.Candidate - has Comparator field which is the same for all Candidates under an MergeIterator instance, we can move the field to MergeIterator level. Candidate is 4.8% of all allocations and we can save 20% (~1% of all allocations) of it for JDK 21 with compressed references on.
switch from ArrayList to array in org.apache.cassandra.db.rows.Row.Merger
The ArrayList iterator costs 0.72% and BulkIterator.Adapter costs 0.35%. So, in total we can save here ~1% of total allocations.
patch by Dmitry Konstantinov; reviewed by TBD for CASSANDRA-21359