netudima commented on code in PR #4739:
URL: https://github.com/apache/cassandra/pull/4739#discussion_r3074782734
##########
src/java/org/apache/cassandra/db/ReadResponse.java:
##########
@@ -239,10 +247,21 @@ private LocalDataResponse(UnfilteredPartitionIterator
iter, ColumnFilter selecti
private static ByteBuffer build(UnfilteredPartitionIterator iter,
ColumnFilter selection)
{
- try (DataOutputBuffer buffer = new DataOutputBuffer())
+ int initialBufferSize = bufferInitialSizeMin;
+
+ if (bufferInitialSizeMax > bufferInitialSizeMin)
+ {
+ // Size output buffer to 10% above the moving average to
absorb minor variance and limit rebuffering.
+ double estimatedResponseSize = estimatedResponseBytes.get();
+ double bufferSizeEstimate =
Double.isNaN(estimatedResponseSize) ? bufferInitialSizeMin :
estimatedResponseSize * 1.1;
+ initialBufferSize = Math.min((int) bufferSizeEstimate,
bufferInitialSizeMax);
+ }
+
+ try (DataOutputBuffer buffer = new
DataOutputBuffer(initialBufferSize))
{
UnfilteredPartitionIterators.serializerForIntraNode().serialize(iter,
selection, buffer, MessagingService.current_version);
- return buffer.buffer();
+ estimatedResponseBytes.update(buffer.position());
Review Comment:
nit: do we need to spend time to update MovingAverage if the dynamic logic
is disabled (bufferInitialSizeMax <= bufferInitialSizeMin)?
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