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Introduce BytesTransportResponse to enable lower heap overhead network responses #127112

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Merged
merged 3 commits into from
Apr 24, 2025
Merged

Introduce BytesTransportResponse to enable lower heap overhead network responses #127112

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87438ae
Introduce BytesTransportResponse to enable zero-copy network writes
original-brownbear Apr 21, 2025
ebf398f
Merge remote-tracking branch 'elastic/main' into bytes-transport-resp…
original-brownbear Apr 21, 2025
61f51d5
Dry up serialization
original-brownbear Apr 21, 2025
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71 changes: 44 additions & 27 deletions server/src/main/java/org/elasticsearch/action/search/SearchQueryThenFetchAsyncAction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -226,18 +226,15 @@ public Object[] getResults() {

@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeArray((o, v) -> {
if (v instanceof Exception e) {
o.writeBoolean(false);
o.writeException(e);
out.writeVInt(results.length);
for (Object result : results) {
if (result instanceof Exception e) {
writePerShardException(out, e);
} else {
o.writeBoolean(true);
assert v instanceof QuerySearchResult : v;
((QuerySearchResult) v).writeTo(o);
writePerShardResult(out, (QuerySearchResult) result);
}
}, results);
mergeResult.writeTo(out);
topDocsStats.writeTo(out);
}
writeMergeResult(out, mergeResult, topDocsStats);
}

@Override
Expand Down Expand Up @@ -268,6 +265,25 @@ public boolean decRef() {
}
return false;
}

private static void writeMergeResult(
StreamOutput out,
QueryPhaseResultConsumer.MergeResult mergeResult,
SearchPhaseController.TopDocsStats topDocsStats
) throws IOException {
mergeResult.writeTo(out);
topDocsStats.writeTo(out);
}

private static void writePerShardException(StreamOutput o, Exception e) throws IOException {
o.writeBoolean(false);
o.writeException(e);
}

private static void writePerShardResult(StreamOutput out, SearchPhaseResult result) throws IOException {
out.writeBoolean(true);
result.writeTo(out);
}
}

/**
Expand Down Expand Up @@ -786,27 +802,14 @@ void onShardDone() {
for (int i = 0; i < resultCount; i++) {
var result = queryPhaseResultConsumer.results.get(i);
if (result == null) {
out.writeBoolean(false);
out.writeException(failures.remove(i));
NodeQueryResponse.writePerShardException(out, failures.remove(i));
} else {
// free context id and remove it from the result right away in case we don't need it anymore
if (result instanceof QuerySearchResult q
&& q.getContextId() != null
&& relevantShardIndices.get(q.getShardIndex()) == false
&& q.hasSuggestHits() == false
&& q.getRankShardResult() == null
&& searchRequest.searchRequest.scroll() == null
&& isPartOfPIT(searchRequest.searchRequest, q.getContextId()) == false) {
if (dependencies.searchService.freeReaderContext(q.getContextId())) {
q.clearContextId();
}
}
out.writeBoolean(true);
result.writeTo(out);
maybeFreeContext(result, relevantShardIndices);
NodeQueryResponse.writePerShardResult(out, result);
}
}
mergeResult.writeTo(out);
queryPhaseResultConsumer.topDocsStats.writeTo(out);
NodeQueryResponse.writeMergeResult(out, mergeResult, queryPhaseResultConsumer.topDocsStats);
success = true;
} catch (IOException e) {
handleMergeFailure(e, channelListener);
Expand All @@ -820,6 +823,20 @@ && isPartOfPIT(searchRequest.searchRequest, q.getContextId()) == false) {
ActionListener.respondAndRelease(channelListener, new BytesTransportResponse(new ReleasableBytesReference(out.bytes(), out)));
}

private void maybeFreeContext(SearchPhaseResult result, BitSet relevantShardIndices) {
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@original-brownbear original-brownbear Apr 21, 2025

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This wants to live in QueryPhaseResultConsumer in the near term anyway :) We can release contexts earlier than just at the end of the per-node action if we merge the top hits more frequently.

if (result instanceof QuerySearchResult q
&& q.getContextId() != null
&& relevantShardIndices.get(q.getShardIndex()) == false
&& q.hasSuggestHits() == false
&& q.getRankShardResult() == null
&& searchRequest.searchRequest.scroll() == null
&& isPartOfPIT(searchRequest.searchRequest, q.getContextId()) == false) {
if (dependencies.searchService.freeReaderContext(q.getContextId())) {
q.clearContextId();
}
}
}

private void handleMergeFailure(Exception e, ChannelActionListener<TransportResponse> channelListener) {
queryPhaseResultConsumer.getSuccessfulResults()
.forEach(searchPhaseResult -> releaseLocalContext(dependencies.searchService, searchRequest, searchPhaseResult));
Expand Down