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ScanQueryFrameProcessor: Close CursorHolders as we go along. #17152

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Merged
gianm merged 4 commits into from
Sep 25, 2024
Merged

ScanQueryFrameProcessor: Close CursorHolders as we go along. #17152

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32b7e98
ScanQueryFrameProcessor: Close CursorHolders as we go along.
gianm Sep 25, 2024
69fa29f
Fix other call sites.
gianm Sep 25, 2024
dbe19a8
Fix reference.
gianm Sep 25, 2024
cfcbb3e
Improvements.
gianm Sep 25, 2024
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36 changes: 24 additions & 12 deletions ...stage-query/src/main/java/org/apache/druid/msq/querykit/scan/ScanQueryFrameProcessor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,7 @@ public class ScanQueryFrameProcessor extends BaseLeafFrameProcessor
private final Closer closer = Closer.create();

private Cursor cursor;
private Closeable cursorCloser;
private Segment segment;
private final SimpleSettableOffset cursorOffset = new SimpleAscendingOffset(Integer.MAX_VALUE);
private FrameWriter frameWriter;
Expand Down Expand Up @@ -156,6 +157,7 @@ public ReturnOrAwait<Object> runIncrementally(final IntSet readableInputs) throw
@Override
public void cleanup() throws IOException
{
closer.register(cursorCloser);
closer.register(frameWriter);
closer.register(super::cleanup);
closer.close();
Expand Down Expand Up @@ -221,7 +223,7 @@ protected ReturnOrAwait<SegmentsInputSlice> runWithDataServerQuery(final DataSer
cursorYielder.close();
return ReturnOrAwait.returnObject(handedOffSegments);
} else {
final long rowsFlushed = setNextCursor(cursorYielder.get(), null);
final long rowsFlushed = setNextCursor(cursorYielder.get(), null, null);
closer.register(cursorYielder);
if (rowsFlushed > 0) {
return ReturnOrAwait.runAgain();
Expand Down Expand Up @@ -256,16 +258,16 @@ protected ReturnOrAwait<Unit> runWithSegment(final SegmentWithDescriptor segment
);
}

final CursorHolder cursorHolder = closer.register(
cursorFactory.makeCursorHolder(ScanQueryEngine.makeCursorBuildSpec(query, null))
);
final Cursor nextCursor = cursorHolder.asCursor();
final CursorHolder nextCursorHolder =
cursorFactory.makeCursorHolder(ScanQueryEngine.makeCursorBuildSpec(query, null));
final Cursor nextCursor = nextCursorHolder.asCursor();

if (nextCursor == null) {
// No cursors!
nextCursorHolder.close();
return ReturnOrAwait.returnObject(Unit.instance());
} else {
final long rowsFlushed = setNextCursor(nextCursor, segmentHolder.get().getSegment());
final long rowsFlushed = setNextCursor(nextCursor, nextCursorHolder, segmentHolder.get().getSegment());
assert rowsFlushed == 0; // There's only ever one cursor when running with a segment
}
}
Expand Down Expand Up @@ -302,16 +304,16 @@ protected ReturnOrAwait<Unit> runWithInputChannel(
);
}

final CursorHolder cursorHolder = closer.register(
cursorFactory.makeCursorHolder(ScanQueryEngine.makeCursorBuildSpec(query, null))
);
final Cursor nextCursor = cursorHolder.asCursor();
final CursorHolder nextCursorHolder =
cursorFactory.makeCursorHolder(ScanQueryEngine.makeCursorBuildSpec(query, null));
final Cursor nextCursor = nextCursorHolder.asCursor();

if (nextCursor == null) {
// no cursor
nextCursorHolder.close();
return ReturnOrAwait.returnObject(Unit.instance());
}
final long rowsFlushed = setNextCursor(nextCursor, frameSegment);
final long rowsFlushed = setNextCursor(nextCursor, nextCursorHolder, frameSegment);

if (rowsFlushed > 0) {
return ReturnOrAwait.runAgain();
Expand Down Expand Up @@ -415,10 +417,20 @@ private long flushFrameWriter() throws IOException
}
}

private long setNextCursor(final Cursor cursor, final Segment segment) throws IOException
private long setNextCursor(
final Cursor cursor,
@Nullable final Closeable cursorCloser,
final Segment segment
) throws IOException
{
final long rowsFlushed = flushFrameWriter();
if (this.cursorCloser != null) {
// Close here, don't add to the processor-level Closer, to avoid leaking CursorHolders. We may generate many
// CursorHolders per instance of this processor, and we need to close them as we go, not all at the end.
this.cursorCloser.close();
}
this.cursor = cursor;
this.cursorCloser = cursorCloser;
this.segment = segment;
this.cursorOffset.reset();
return rowsFlushed;
Expand Down