original-brownbear commented on code in PR #13860:
URL: https://github.com/apache/lucene/pull/13860#discussion_r1986157505
##########
lucene/core/src/java/org/apache/lucene/search/IndexSearcher.java:
##########
@@ -360,102 +350,95 @@ public static LeafSlice[] slices(
boolean allowSegmentPartitions) {
// Make a copy so we can sort:
- List<LeafReaderContext> sortedLeaves = new ArrayList<>(leaves);
+ LeafReaderContext[] sortedLeaves = leaves.toArray(new
LeafReaderContext[0]);
// Sort by maxDoc, descending:
- sortedLeaves.sort(Collections.reverseOrder(Comparator.comparingInt(l ->
l.reader().maxDoc())));
+ Arrays.sort(
+ sortedLeaves, (l1, l2) -> Integer.compare(l2.reader().maxDoc(),
l1.reader().maxDoc()));
if (allowSegmentPartitions) {
- final List<List<LeafReaderContextPartition>> groupedLeafPartitions = new
ArrayList<>();
- int currentSliceNumDocs = 0;
- List<LeafReaderContextPartition> group = null;
- for (LeafReaderContext ctx : sortedLeaves) {
- if (ctx.reader().maxDoc() > maxDocsPerSlice) {
- assert group == null;
- // if the segment does not fit in a single slice, we split it into
maximum 5 partitions of
- // equal size
- int numSlices = Math.min(5, Math.ceilDiv(ctx.reader().maxDoc(),
maxDocsPerSlice));
- int numDocs = ctx.reader().maxDoc() / numSlices;
- int maxDocId = numDocs;
- int minDocId = 0;
- for (int i = 0; i < numSlices - 1; i++) {
- groupedLeafPartitions.add(
- Collections.singletonList(
- LeafReaderContextPartition.createFromAndTo(ctx, minDocId,
maxDocId)));
- minDocId = maxDocId;
- maxDocId += numDocs;
- }
- // the last slice gets all the remaining docs
- groupedLeafPartitions.add(
- Collections.singletonList(
- LeafReaderContextPartition.createFromAndTo(
- ctx, minDocId, ctx.reader().maxDoc())));
- } else {
- if (group == null) {
- group = new ArrayList<>();
- groupedLeafPartitions.add(group);
- }
- group.add(LeafReaderContextPartition.createForEntireSegment(ctx));
-
- currentSliceNumDocs += ctx.reader().maxDoc();
- // We only split a segment when it does not fit entirely in a slice.
We don't partition
- // the
- // segment that makes the current slice (which holds multiple
segments) go over
- // maxDocsPerSlice. This means that a slice either contains multiple
entire segments, or a
- // single partition of a segment.
- if (group.size() >= maxSegmentsPerSlice || currentSliceNumDocs >
maxDocsPerSlice) {
- group = null;
- currentSliceNumDocs = 0;
- }
- }
- }
+ return slicesWithPartitionedSegments(maxDocsPerSlice,
maxSegmentsPerSlice, sortedLeaves);
+ }
- LeafSlice[] slices = new LeafSlice[groupedLeafPartitions.size()];
- int upto = 0;
- for (List<LeafReaderContextPartition> currentGroup :
groupedLeafPartitions) {
- slices[upto] = new LeafSlice(currentGroup);
- ++upto;
+ final List<LeafSlice> groupedLeaves = new ArrayList<>();
+ long docSum = 0;
+ List<LeafReaderContextPartition> group = null;
+ for (LeafReaderContext ctx : sortedLeaves) {
+ final int maxDoc = ctx.reader().maxDoc();
+ var partition = LeafReaderContextPartition.createForEntireSegment(ctx);
+ if (maxDoc > maxDocsPerSlice) {
+ assert group == null;
+ groupedLeaves.add(new LeafSlice(Collections.singletonList(partition)));
+ } else {
+ if (group == null) {
+ group = new ArrayList<>();
+ }
+ group.add(partition);
+ docSum += maxDoc;
+ if (docSum > maxDocsPerSlice || group.size() >= maxSegmentsPerSlice) {
+ groupedLeaves.add(new LeafSlice(group));
+ group = null;
+ docSum = 0;
+ }
}
- return slices;
}
+ if (group != null) {
+ groupedLeaves.add(new LeafSlice(group));
+ }
+ return groupedLeaves.toArray(LeafSlice.EMPTY_ARRAY);
+ }
- final List<List<LeafReaderContext>> groupedLeaves = new ArrayList<>();
- long docSum = 0;
- List<LeafReaderContext> group = null;
+ private static LeafSlice[] slicesWithPartitionedSegments(
+ int maxDocsPerSlice, int maxSegmentsPerSlice, LeafReaderContext[]
sortedLeaves) {
+ final List<List<LeafReaderContextPartition>> groupedLeafPartitions = new
ArrayList<>();
+ int currentSliceNumDocs = 0;
+ List<LeafReaderContextPartition> group = null;
for (LeafReaderContext ctx : sortedLeaves) {
if (ctx.reader().maxDoc() > maxDocsPerSlice) {
assert group == null;
- groupedLeaves.add(Collections.singletonList(ctx));
+ // if the segment does not fit in a single slice, we split it into
maximum 5 partitions of
+ // equal size
+ int numSlices = Math.min(5, Math.ceilDiv(ctx.reader().maxDoc(),
maxDocsPerSlice));
+ int numDocs = ctx.reader().maxDoc() / numSlices;
+ int maxDocId = numDocs;
+ int minDocId = 0;
+ for (int i = 0; i < numSlices - 1; i++) {
+ groupedLeafPartitions.add(
+ Collections.singletonList(
+ LeafReaderContextPartition.createFromAndTo(ctx, minDocId,
maxDocId)));
+ minDocId = maxDocId;
+ maxDocId += numDocs;
+ }
+ // the last slice gets all the remaining docs
+ groupedLeafPartitions.add(
+ Collections.singletonList(
+ LeafReaderContextPartition.createFromAndTo(ctx, minDocId,
ctx.reader().maxDoc())));
} else {
if (group == null) {
group = new ArrayList<>();
- group.add(ctx);
-
- groupedLeaves.add(group);
- } else {
- group.add(ctx);
+ groupedLeafPartitions.add(group);
}
-
- docSum += ctx.reader().maxDoc();
- if (group.size() >= maxSegmentsPerSlice || docSum > maxDocsPerSlice) {
+ group.add(LeafReaderContextPartition.createForEntireSegment(ctx));
+
+ currentSliceNumDocs += ctx.reader().maxDoc();
+ // We only split a segment when it does not fit entirely in a slice.
We don't partition
+ // the
+ // segment that makes the current slice (which holds multiple
segments) go over
+ // maxDocsPerSlice. This means that a slice either contains multiple
entire segments, or a
+ // single partition of a segment.
+ if (group.size() >= maxSegmentsPerSlice || currentSliceNumDocs >
maxDocsPerSlice) {
group = null;
- docSum = 0;
+ currentSliceNumDocs = 0;
}
}
}
- LeafSlice[] slices = new LeafSlice[groupedLeaves.size()];
+ LeafSlice[] slices = new LeafSlice[groupedLeafPartitions.size()];
int upto = 0;
- for (List<LeafReaderContext> currentLeaf : groupedLeaves) {
- slices[upto] =
- new LeafSlice(
- new ArrayList<>(
- currentLeaf.stream()
- .map(LeafReaderContextPartition::createForEntireSegment)
- .toList()));
+ for (List<LeafReaderContextPartition> currentGroup :
groupedLeafPartitions) {
+ slices[upto] = new LeafSlice(currentGroup);
Review Comment:
Done in https://github.com/apache/lucene/pull/14336 sorry for delay on this
one :) But after benchmarking a little more as of late, this is more valuable
than ever for us. Especially for large segment count use-cases this logic tends
to make up a non-trivial part of the total execution time of the query phase
(as in up to O(10%)) without this fix (close to an order of magnitude cheaper
with all the fixes in here in ES use cases seemingly ... probably due to
instruction cache/code-size issues as it turned out now :)).
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