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Add BatchPartitioner (#2285) #2287

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merged 3 commits into from
Apr 20, 2022
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Add BatchPartitioner (#2285) #2287

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e453d28
Add BatchPartitioner (#2285)
tustvold Apr 20, 2022
e1a002f
Don't panic on unknown partitioning scheme
tustvold Apr 20, 2022
7c975a1
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tustvold Apr 20, 2022
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Add BatchPartitioner (#2285)
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@tustvold
tustvold committed Apr 20, 2022
commit e453d2820970c2fc0f04691adb1a8214aafe09d2
109 changes: 41 additions & 68 deletions ballista/rust/core/src/execution_plans/shuffle_writer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,16 +34,13 @@ use crate::serde::protobuf::ShuffleWritePartition;
use crate::serde::scheduler::PartitionStats;
use async_trait::async_trait;
use datafusion::arrow::array::{
Array, ArrayBuilder, ArrayRef, StringBuilder, StructBuilder, UInt32Builder,
UInt64Builder,
ArrayBuilder, ArrayRef, StringBuilder, StructBuilder, UInt32Builder, UInt64Builder,
};
use datafusion::arrow::compute::take;
use datafusion::arrow::datatypes::{DataType, Field, Schema, SchemaRef};

use datafusion::arrow::record_batch::RecordBatch;
use datafusion::error::{DataFusionError, Result};
use datafusion::physical_plan::common::IPCWriter;
use datafusion::physical_plan::hash_utils::create_hashes;
use datafusion::physical_plan::memory::MemoryStream;
use datafusion::physical_plan::metrics::{
self, ExecutionPlanMetricsSet, MetricBuilder, MetricsSet,
Expand All @@ -55,6 +52,7 @@ use datafusion::physical_plan::{
use futures::StreamExt;

use datafusion::execution::context::TaskContext;
use datafusion::physical_plan::repartition::BatchPartitioner;
use log::{debug, info};

/// ShuffleWriterExec represents a section of a query plan that has consistent partitioning and
Expand All @@ -81,20 +79,24 @@ pub struct ShuffleWriterExec {
struct ShuffleWriteMetrics {
/// Time spend writing batches to shuffle files
write_time: metrics::Time,
repart_time: metrics::Time,
input_rows: metrics::Count,
output_rows: metrics::Count,
}

impl ShuffleWriteMetrics {
fn new(partition: usize, metrics: &ExecutionPlanMetricsSet) -> Self {
let write_time = MetricBuilder::new(metrics).subset_time("write_time", partition);
let repart_time =
MetricBuilder::new(metrics).subset_time("repart_time", partition);

let input_rows = MetricBuilder::new(metrics).counter("input_rows", partition);

let output_rows = MetricBuilder::new(metrics).output_rows(partition);

Self {
write_time,
repart_time,
input_rows,
output_rows,
}
Expand Down Expand Up @@ -202,77 +204,48 @@ impl ShuffleWriterExec {
writers.push(None);
}

let hashes_buf = &mut vec![];
let random_state = ahash::RandomState::with_seeds(0, 0, 0, 0);
let mut partitioner = BatchPartitioner::new(
Partitioning::Hash(exprs.clone(), *n),
write_metrics.repart_time.clone(),
);

while let Some(result) = stream.next().await {
let input_batch = result?;

write_metrics.input_rows.add(input_batch.num_rows());

let arrays = exprs
.iter()
.map(|expr| {
Ok(expr
.evaluate(&input_batch)?
.into_array(input_batch.num_rows()))
})
.collect::<Result<Vec<_>>>()?;
hashes_buf.clear();
hashes_buf.resize(arrays[0].len(), 0);
// Hash arrays and compute buckets based on number of partitions
let hashes = create_hashes(&arrays, &random_state, hashes_buf)?;
let mut indices = vec![vec![]; num_output_partitions];
for (index, hash) in hashes.iter().enumerate() {
indices[(*hash % num_output_partitions as u64) as usize]
.push(index as u64)
}
for (output_partition, partition_indices) in
indices.into_iter().enumerate()
{
let indices = partition_indices.into();

// Produce batches based on indices
let columns = input_batch
.columns()
.iter()
.map(|c| {
take(c.as_ref(), &indices, None).map_err(|e| {
DataFusionError::Execution(e.to_string())
})
})
.collect::<Result<Vec<Arc<dyn Array>>>>()?;

let output_batch =
RecordBatch::try_new(input_batch.schema(), columns)?;

// write non-empty batch out

// TODO optimize so we don't write or fetch empty partitions
// if output_batch.num_rows() > 0 {
let timer = write_metrics.write_time.timer();
match &mut writers[output_partition] {
Some(w) => {
w.write(&output_batch)?;
}
None => {
let mut path = path.clone();
path.push(&format!("{}", output_partition));
std::fs::create_dir_all(&path)?;

path.push(format!("data-{}.arrow", input_partition));
info!("Writing results to {:?}", path);

let mut writer =
IPCWriter::new(&path, stream.schema().as_ref())?;

writer.write(&output_batch)?;
writers[output_partition] = Some(writer);
partitioner.partition(
input_batch,
|output_partition, output_batch| {
// write non-empty batch out

// TODO optimize so we don't write or fetch empty partitions
// if output_batch.num_rows() > 0 {
let timer = write_metrics.write_time.timer();
match &mut writers[output_partition] {
Some(w) => {
w.write(&output_batch)?;
}
None => {
let mut path = path.clone();
path.push(&format!("{}", output_partition));
std::fs::create_dir_all(&path)?;

path.push(format!("data-{}.arrow", input_partition));
info!("Writing results to {:?}", path);

let mut writer =
IPCWriter::new(&path, stream.schema().as_ref())?;

writer.write(&output_batch)?;
writers[output_partition] = Some(writer);
}
}
}
write_metrics.output_rows.add(output_batch.num_rows());
timer.done();
}
write_metrics.output_rows.add(output_batch.num_rows());
timer.done();
Ok(())
},
)?;
}

let mut part_locs = vec![];
Expand Down
5 changes: 5 additions & 0 deletions datafusion/core/src/physical_plan/metrics/value.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,11 @@ impl<'a> ScopedTimerGuard<'a> {
}
}

/// Restarts the timer recording from the current time
pub fn restart(&mut self) {
self.start = Some(Instant::now())
}

/// Stop the timer, record the time taken and consume self
pub fn done(mut self) {
self.stop()
Expand Down
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