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new 77e4d05fe0 [Json] Add json reader benchmarks for Map and REE (#9616)
77e4d05fe0 is described below
commit 77e4d05fe0f199ccfaad578e58278329534a9c3d
Author: Liam Bao <[email protected]>
AuthorDate: Tue Mar 31 09:59:46 2026 -0400
[Json] Add json reader benchmarks for Map and REE (#9616)
# Which issue does this PR close?
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enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax.
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- Relates to #9497.
# Rationale for this change
<!--
Why are you proposing this change? If this is already explained clearly
in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand
your changes and offer better suggestions for fixes.
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# What changes are included in this PR?
<!--
There is no need to duplicate the description in the issue here but it
is sometimes worth providing a summary of the individual changes in this
PR.
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As part of the effort to move the Json reader away from `ArrayData`
toward typed `ArrayRef` APIs, it's necessary to change the
`ArrayDecoder::decode` interface to return `ArrayRef` directly and
updates all decoder implementations (list, struct, map, run-end encoded)
to construct typed arrays without intermediate `ArrayData` round-trips.
New benchmarks for map and run-end encoded decoding are added to verify
there is no performance regression.
# Are these changes tested?
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Yes
# Are there any user-facing changes?
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No
---
arrow-json/benches/json_reader.rs | 195 +++++++++++++++++++++++++++++++++++---
1 file changed, 184 insertions(+), 11 deletions(-)
diff --git a/arrow-json/benches/json_reader.rs
b/arrow-json/benches/json_reader.rs
index fccac68d9b..9d0dd8e9a1 100644
--- a/arrow-json/benches/json_reader.rs
+++ b/arrow-json/benches/json_reader.rs
@@ -28,14 +28,28 @@ use std::fmt::Write;
use std::hint::black_box;
use std::sync::Arc;
+// Shared
const ROWS: usize = 1 << 17; // 128K rows
const BATCH_SIZE: usize = 1 << 13; // 8K rows per batch
+// Wide object / struct
const WIDE_FIELDS: usize = 64;
-const BINARY_BYTES: usize = 64;
const WIDE_PROJECTION_TOTAL_FIELDS: usize = 100; // 100 fields total, select
only 3
-const LIST_SHORT_ELEMENTS: usize = 5;
-const LIST_LONG_ELEMENTS: usize = 100;
+
+// Binary
+const BINARY_BYTES: usize = 64;
+
+// List
+const SHORT_LIST_ELEMENTS: usize = 5;
+const LONG_LIST_ELEMENTS: usize = 100;
+
+// Map
+const SMALL_MAP_ENTRIES: usize = 5;
+const LARGE_MAP_ENTRIES: usize = 50;
+
+// Run-end encoded
+const SHORT_REE_RUN_LENGTH: usize = 2;
+const LONG_REE_RUN_LENGTH: usize = 100;
fn decode_and_flush(decoder: &mut Decoder, data: &[u8]) {
let mut offset = 0;
@@ -289,19 +303,174 @@ fn bench_decode_list(c: &mut Criterion) {
let schema = build_list_schema();
// Short lists: tests list handling overhead (few elements per row)
- let short_data = build_list_json(ROWS, LIST_SHORT_ELEMENTS);
- bench_decode_schema(c, "decode_list_short_i64_json", &short_data,
schema.clone());
+ let short_data = build_list_json(ROWS, SHORT_LIST_ELEMENTS);
+ bench_decode_schema(c, "decode_short_list_i64_json", &short_data,
schema.clone());
// Long lists: tests child element decode throughput (many elements per
row)
- let long_data = build_list_json(ROWS, LIST_LONG_ELEMENTS);
- bench_decode_schema(c, "decode_list_long_i64_json", &long_data, schema);
+ let long_data = build_list_json(ROWS, LONG_LIST_ELEMENTS);
+ bench_decode_schema(c, "decode_long_list_i64_json", &long_data, schema);
}
fn bench_serialize_list(c: &mut Criterion) {
let schema = build_list_schema();
- let short_values = build_list_values(ROWS, LIST_SHORT_ELEMENTS);
- c.bench_function("decode_list_short_i64_serialize", |b| {
+ let short_values = build_list_values(ROWS, SHORT_LIST_ELEMENTS);
+ c.bench_function("decode_short_list_i64_serialize", |b| {
+ b.iter(|| {
+ let mut decoder = ReaderBuilder::new(schema.clone())
+ .with_batch_size(BATCH_SIZE)
+ .build_decoder()
+ .unwrap();
+ decoder.serialize(&short_values).unwrap();
+ while let Some(_batch) = decoder.flush().unwrap() {}
+ })
+ });
+
+ let long_values = build_list_values(ROWS, LONG_LIST_ELEMENTS);
+ c.bench_function("decode_long_list_i64_serialize", |b| {
+ b.iter(|| {
+ let mut decoder = ReaderBuilder::new(schema.clone())
+ .with_batch_size(BATCH_SIZE)
+ .build_decoder()
+ .unwrap();
+ decoder.serialize(&long_values).unwrap();
+ while let Some(_batch) = decoder.flush().unwrap() {}
+ })
+ });
+}
+
+fn build_map_json(rows: usize, entries: usize) -> Vec<u8> {
+ let mut out = String::with_capacity(rows * (entries * 20 + 16));
+ for row in 0..rows {
+ out.push_str("{\"map\":{");
+ for i in 0..entries {
+ if i > 0 {
+ out.push(',');
+ }
+ write!(&mut out, "\"k{}\":{}", i, (row + i) as i64).unwrap();
+ }
+ out.push_str("}}\n");
+ }
+ out.into_bytes()
+}
+
+fn build_map_values(rows: usize, entries: usize) -> Vec<Value> {
+ let mut out = Vec::with_capacity(rows);
+ for row in 0..rows {
+ let mut inner = Map::with_capacity(entries);
+ for i in 0..entries {
+ inner.insert(
+ format!("k{i}"),
+ Value::Number(Number::from((row + i) as i64)),
+ );
+ }
+ let mut map = Map::with_capacity(1);
+ map.insert("map".to_string(), Value::Object(inner));
+ out.push(Value::Object(map));
+ }
+ out
+}
+
+fn build_map_schema() -> Arc<Schema> {
+ let entries_field = Arc::new(Field::new(
+ "entries",
+ DataType::Struct(
+ vec![
+ Field::new("keys", DataType::Utf8, false),
+ Field::new("values", DataType::Int64, true),
+ ]
+ .into(),
+ ),
+ false,
+ ));
+ Arc::new(Schema::new(vec![Field::new(
+ "map",
+ DataType::Map(entries_field, false),
+ false,
+ )]))
+}
+
+fn bench_decode_map(c: &mut Criterion) {
+ let schema = build_map_schema();
+
+ let small_data = build_map_json(ROWS, SMALL_MAP_ENTRIES);
+ bench_decode_schema(c, "decode_small_map_json", &small_data,
schema.clone());
+
+ let large_data = build_map_json(ROWS, LARGE_MAP_ENTRIES);
+ bench_decode_schema(c, "decode_large_map_json", &large_data, schema);
+}
+
+fn bench_serialize_map(c: &mut Criterion) {
+ let schema = build_map_schema();
+
+ let small_values = build_map_values(ROWS, SMALL_MAP_ENTRIES);
+ c.bench_function("decode_small_map_serialize", |b| {
+ b.iter(|| {
+ let mut decoder = ReaderBuilder::new(schema.clone())
+ .with_batch_size(BATCH_SIZE)
+ .build_decoder()
+ .unwrap();
+ decoder.serialize(&small_values).unwrap();
+ while let Some(_batch) = decoder.flush().unwrap() {}
+ })
+ });
+
+ let large_values = build_map_values(ROWS, LARGE_MAP_ENTRIES);
+ c.bench_function("decode_large_map_serialize", |b| {
+ b.iter(|| {
+ let mut decoder = ReaderBuilder::new(schema.clone())
+ .with_batch_size(BATCH_SIZE)
+ .build_decoder()
+ .unwrap();
+ decoder.serialize(&large_values).unwrap();
+ while let Some(_batch) = decoder.flush().unwrap() {}
+ })
+ });
+}
+
+fn build_ree_json(rows: usize, run_length: usize) -> Vec<u8> {
+ let mut out = String::with_capacity(rows * 24);
+ for row in 0..rows {
+ let value = (row / run_length) as i64;
+ writeln!(&mut out, "{{\"val\":{value}}}").unwrap();
+ }
+ out.into_bytes()
+}
+
+fn build_ree_values(rows: usize, run_length: usize) -> Vec<Value> {
+ let mut out = Vec::with_capacity(rows);
+ for row in 0..rows {
+ let value = (row / run_length) as i64;
+ let mut map = Map::with_capacity(1);
+ map.insert("val".to_string(), Value::Number(Number::from(value)));
+ out.push(Value::Object(map));
+ }
+ out
+}
+
+fn build_ree_schema() -> Arc<Schema> {
+ let ree_type = DataType::RunEndEncoded(
+ Arc::new(Field::new("run_ends", DataType::Int32, false)),
+ Arc::new(Field::new("values", DataType::Int64, true)),
+ );
+ Arc::new(Schema::new(vec![Field::new("val", ree_type, false)]))
+}
+
+fn bench_decode_ree(c: &mut Criterion) {
+ let schema = build_ree_schema();
+
+ let short_data = build_ree_json(ROWS, SHORT_REE_RUN_LENGTH);
+ bench_decode_schema(c, "decode_short_ree_runs_json", &short_data,
schema.clone());
+
+ let long_data = build_ree_json(ROWS, LONG_REE_RUN_LENGTH);
+ bench_decode_schema(c, "decode_long_ree_runs_json", &long_data, schema);
+}
+
+fn bench_serialize_ree(c: &mut Criterion) {
+ let schema = build_ree_schema();
+
+ let short_values = build_ree_values(ROWS, SHORT_REE_RUN_LENGTH);
+ c.bench_function("decode_short_ree_runs_serialize", |b| {
b.iter(|| {
let mut decoder = ReaderBuilder::new(schema.clone())
.with_batch_size(BATCH_SIZE)
@@ -312,8 +481,8 @@ fn bench_serialize_list(c: &mut Criterion) {
})
});
- let long_values = build_list_values(ROWS, LIST_LONG_ELEMENTS);
- c.bench_function("decode_list_long_i64_serialize", |b| {
+ let long_values = build_ree_values(ROWS, LONG_REE_RUN_LENGTH);
+ c.bench_function("decode_long_ree_runs_serialize", |b| {
b.iter(|| {
let mut decoder = ReaderBuilder::new(schema.clone())
.with_batch_size(BATCH_SIZE)
@@ -402,6 +571,10 @@ criterion_group!(
bench_wide_projection,
bench_decode_list,
bench_serialize_list,
+ bench_decode_map,
+ bench_serialize_map,
+ bench_decode_ree,
+ bench_serialize_ree,
bench_schema_inference
);
criterion_main!(benches);
