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chore: Reduce timer overhead in native shuffle writer #2941

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Merged
andygrove merged 2 commits into from
Dec 19, 2025
Merged

chore: Reduce timer overhead in native shuffle writer #2941

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c54cb62
reduce timer overhead in native shuffle writer
andygrove Dec 19, 2025
7dde67b
update jvm refs
andygrove Dec 19, 2025
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20 changes: 1 addition & 19 deletions native/core/src/execution/shuffle/shuffle_writer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -275,9 +275,6 @@ struct ShuffleRepartitionerMetrics {
/// Time to perform repartitioning
repart_time: Time,

/// Time interacting with memory pool
mempool_time: Time,

/// Time encoding batches to IPC format
encode_time: Time,

Expand All @@ -302,7 +299,6 @@ impl ShuffleRepartitionerMetrics {
Self {
baseline: BaselineMetrics::new(metrics, partition),
repart_time: MetricBuilder::new(metrics).subset_time("repart_time", partition),
mempool_time: MetricBuilder::new(metrics).subset_time("mempool_time", partition),
encode_time: MetricBuilder::new(metrics).subset_time("encode_time", partition),
write_time: MetricBuilder::new(metrics).subset_time("write_time", partition),
input_batches: MetricBuilder::new(metrics).counter("input_batches", partition),
Expand Down Expand Up @@ -648,13 +644,7 @@ impl MultiPartitionShuffleRepartitioner {
mem_growth += after_size.saturating_sub(before_size);
}

let grow_result = {
let mut timer = self.metrics.mempool_time.timer();
let result = self.reservation.try_grow(mem_growth);
timer.stop();
result
};
if grow_result.is_err() {
if self.reservation.try_grow(mem_growth).is_err() {
self.spill()?;
}

Expand Down Expand Up @@ -737,9 +727,7 @@ impl MultiPartitionShuffleRepartitioner {
)?;
}

let mut timer = self.metrics.mempool_time.timer();
self.reservation.free();
timer.stop();
self.metrics.spill_count.add(1);
self.metrics.spilled_bytes.add(spilled_bytes);
Ok(())
Expand Down Expand Up @@ -952,8 +940,6 @@ impl ShufflePartitioner for SinglePartitionShufflePartitioner {
if num_rows >= self.batch_size || num_rows + self.num_buffered_rows > self.batch_size {
let concatenated_batch = self.concat_buffered_batches()?;

let write_start_time = Instant::now();
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@andygrove andygrove Dec 19, 2025

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Removing this one is actually a bug fix rather than an optimiation. The timer was already being passed into functions that perform the writes.


// Write the concatenated buffered batch
if let Some(batch) = concatenated_batch {
self.output_data_writer.write(
Expand All @@ -974,10 +960,6 @@ impl ShufflePartitioner for SinglePartitionShufflePartitioner {
// Add the new batch to the buffer
self.add_buffered_batch(batch);
}

self.metrics
.write_time
.add_duration(write_start_time.elapsed());
} else {
self.add_buffered_batch(batch);
}
Expand Down
1 change: 0 additions & 1 deletion spark/src/main/scala/org/apache/spark/sql/comet/CometMetricNode.scala
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Expand Up @@ -247,7 +247,6 @@ object CometMetricNode {
def shuffleMetrics(sc: SparkContext): Map[String, SQLMetric] = {
Map(
"elapsed_compute" -> SQLMetrics.createNanoTimingMetric(sc, "native shuffle writer time"),
"mempool_time" -> SQLMetrics.createNanoTimingMetric(sc, "memory pool time"),
"repart_time" -> SQLMetrics.createNanoTimingMetric(sc, "repartition time"),
"encode_time" -> SQLMetrics.createNanoTimingMetric(sc, "encoding and compression time"),
"decode_time" -> SQLMetrics.createNanoTimingMetric(sc, "decoding and decompression time"),
Expand Down
1 change: 0 additions & 1 deletion ...rc/main/scala/org/apache/spark/sql/comet/execution/shuffle/CometNativeShuffleWriter.scala
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Expand Up @@ -79,7 +79,6 @@ class CometNativeShuffleWriter[K, V](
"elapsed_compute",
"encode_time",
"repart_time",
"mempool_time",
"input_batches",
"spill_count",
"spilled_bytes")
Expand Down
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