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Validate the memory consumption in SPM created by multi level merge #17029

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5e9fe83
use GreedyMemoryPool for sanity check
ding-young Aug 4, 2025
0c65f27
validate whether batch read from spill exceeds max_record_batch_mem
ding-young Aug 8, 2025
68cffc6
chore: remove printlns
ding-young Aug 8, 2025
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1 change: 0 additions & 1 deletion datafusion/execution/src/memory_pool/pool.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,6 @@ pub struct GreedyMemoryPool {
impl GreedyMemoryPool {
/// Create a new pool that can allocate up to `pool_size` bytes
pub fn new(pool_size: usize) -> Self {
debug!("Created new GreedyMemoryPool(pool_size={pool_size})");
Self {
pool_size,
used: AtomicUsize::new(0),
Expand Down
14 changes: 9 additions & 5 deletions datafusion/physical-plan/benches/spill_io.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,8 +115,9 @@ fn bench_spill_io(c: &mut Criterion) {
// - Wait for the consumer to finish processing
|spill_file| {
rt.block_on(async {
let stream =
spill_manager.read_spill_as_stream(spill_file).unwrap();
let stream = spill_manager
.read_spill_as_stream(spill_file, None)
.unwrap();
let _ = collect(stream).await.unwrap();
})
},
Expand Down Expand Up @@ -519,8 +520,9 @@ fn benchmark_spill_batches_for_all_codec(
)
.unwrap()
.unwrap();
let stream =
spill_manager.read_spill_as_stream(spill_file).unwrap();
let stream = spill_manager
.read_spill_as_stream(spill_file, None)
.unwrap();
let _ = collect(stream).await.unwrap();
})
},
Expand Down Expand Up @@ -553,7 +555,9 @@ fn benchmark_spill_batches_for_all_codec(
let rt = Runtime::new().unwrap();
let start = Instant::now();
rt.block_on(async {
let stream = spill_manager.read_spill_as_stream(spill_file).unwrap();
let stream = spill_manager
.read_spill_as_stream(spill_file, None)
.unwrap();
let _ = collect(stream).await.unwrap();
});
let read_time = start.elapsed();
Expand Down
9 changes: 6 additions & 3 deletions datafusion/physical-plan/src/sorts/multi_level_merge.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -237,7 +237,8 @@ impl MultiLevelMergeBuilder {
let spill_file = self.sorted_spill_files.remove(0);

// Not reserving any memory for this disk as we are not holding it in memory
self.spill_manager.read_spill_as_stream(spill_file.file)
self.spill_manager
.read_spill_as_stream(spill_file.file, None)
}

// Only in memory streams, so merge them all in a single pass
Expand Down Expand Up @@ -274,10 +275,12 @@ impl MultiLevelMergeBuilder {
.spill_manager
.clone()
.with_batch_read_buffer_capacity(buffer_size)
.read_spill_as_stream(spill.file)?;
.read_spill_as_stream(
spill.file,
Some(spill.max_record_batch_memory),
)?;
sorted_streams.push(stream);
}

let merge_sort_stream = self.create_new_merge_sort(
sorted_streams,
// If we have no sorted spill files left, this is the last run
Expand Down
47 changes: 40 additions & 7 deletions datafusion/physical-plan/src/spill/mod.rs
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Expand Up @@ -54,8 +54,13 @@ use futures::{FutureExt as _, Stream};
struct SpillReaderStream {
schema: SchemaRef,
state: SpillReaderStreamState,
/// how much memory the largest memory batch is taking
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I recommend to also explain: this is used for validation, and link to the multi-level merge's doc for the background.

pub max_record_batch_memory: Option<usize>,
}

// Small margin allowed to accommodate slight memory accounting variation
const MEMORY_MARGIN: usize = 4096;

/// When we poll for the next batch, we will get back both the batch and the reader,
/// so we can call `next` again.
type NextRecordBatchResult = Result<(StreamReader<BufReader<File>>, Option<RecordBatch>)>;
Expand All @@ -76,10 +81,15 @@ enum SpillReaderStreamState {
}

impl SpillReaderStream {
fn new(schema: SchemaRef, spill_file: RefCountedTempFile) -> Self {
fn new(
schema: SchemaRef,
spill_file: RefCountedTempFile,
max_record_batch_memory: Option<usize>,
) -> Self {
Self {
schema,
state: SpillReaderStreamState::Uninitialized(spill_file),
max_record_batch_memory,
}
}

Expand Down Expand Up @@ -125,6 +135,27 @@ impl SpillReaderStream {
Ok((reader, batch)) => {
match batch {
Some(batch) => {
if let Some(max_record_batch_memory) =
self.max_record_batch_memory
{
let actual_size =
get_record_batch_memory_size(&batch);
if actual_size
> max_record_batch_memory + MEMORY_MARGIN
{
return Poll::Ready(Some(Err(
DataFusionError::ResourcesExhausted(
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We can use resources_err!(...) macro here

format!(
"Record batch memory usage ({actual_size} bytes) exceeds the expected limit ({max_record_batch_memory} bytes)\n
by more than the allowed tolerance ({MEMORY_MARGIN} bytes).\n
This likely indicates a bug in memory accounting during spilling.\n
Please report this issue",
)
.to_owned(),
),
)));
}
}
self.state = SpillReaderStreamState::Waiting(reader);

Poll::Ready(Some(Ok(batch)))
Expand Down Expand Up @@ -389,7 +420,7 @@ mod tests {
let spilled_rows = spill_manager.metrics.spilled_rows.value();
assert_eq!(spilled_rows, num_rows);

let stream = spill_manager.read_spill_as_stream(spill_file)?;
let stream = spill_manager.read_spill_as_stream(spill_file, None)?;
assert_eq!(stream.schema(), schema);

let batches = collect(stream).await?;
Expand Down Expand Up @@ -453,7 +484,7 @@ mod tests {
let spilled_rows = spill_manager.metrics.spilled_rows.value();
assert_eq!(spilled_rows, num_rows);

let stream = spill_manager.read_spill_as_stream(spill_file)?;
let stream = spill_manager.read_spill_as_stream(spill_file, None)?;
assert_eq!(stream.schema(), dict_schema);
let batches = collect(stream).await?;
assert_eq!(batches.len(), 2);
Expand All @@ -479,7 +510,7 @@ mod tests {
.unwrap();
assert!(spill_file.path().exists());

let stream = spill_manager.read_spill_as_stream(spill_file)?;
let stream = spill_manager.read_spill_as_stream(spill_file, None)?;
assert_eq!(stream.schema(), schema);

let batches = collect(stream).await?;
Expand Down Expand Up @@ -514,7 +545,7 @@ mod tests {
let spilled_rows = spill_manager.metrics.spilled_rows.value();
assert_eq!(spilled_rows, num_rows);

let stream = spill_manager.read_spill_as_stream(spill_file)?;
let stream = spill_manager.read_spill_as_stream(spill_file, None)?;
assert_eq!(stream.schema(), schema);

let batches = collect(stream).await?;
Expand Down Expand Up @@ -894,8 +925,10 @@ mod tests {
.spill_record_batch_and_finish(&batches, "Test2")?
.unwrap();

let mut stream_1 = spill_manager.read_spill_as_stream(spill_file_1)?;
let mut stream_2 = spill_manager.read_spill_as_stream(spill_file_2)?;
let mut stream_1 =
spill_manager.read_spill_as_stream(spill_file_1, None)?;
let mut stream_2 =
spill_manager.read_spill_as_stream(spill_file_2, None)?;
stream_1.next().await;
stream_2.next().await;

Expand Down
2 changes: 2 additions & 0 deletions datafusion/physical-plan/src/spill/spill_manager.rs
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Expand Up @@ -201,10 +201,12 @@ impl SpillManager {
pub fn read_spill_as_stream(
&self,
spill_file_path: RefCountedTempFile,
max_record_batch_memory: Option<usize>,
) -> Result<SendableRecordBatchStream> {
let stream = Box::pin(cooperative(SpillReaderStream::new(
Arc::clone(&self.schema),
spill_file_path,
max_record_batch_memory,
)));

Ok(spawn_buffered(stream, self.batch_read_buffer_capacity))
Expand Down
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