Improved performance of deserializing JSON (2x)

Cargo.toml

@@ -39,9 +39,7 @@ regex = { version = "^1.3", optional = true }
 streaming-iterator = { version = "0.1", optional = true }
 fallible-streaming-iterator = { version = "0.1", optional = true }
 
-serde = { version = "^1.0", features = ["rc"], optional = true }
-serde_derive = { version = "^1.0", optional = true }
-serde_json = { version = "^1.0", features = ["preserve_order"], optional = true }
+json-deserializer = { version = "0.3", optional = true }
 indexmap = { version = "^1.6", optional = true }
 
 # used to print columns in a nice columnar format
@@ -72,6 +70,9 @@ parquet2 = { version = "0.13", optional = true, default_features = false }
 
 # avro support
 avro-schema = { version = "0.2", optional = true }
+serde = { version = "^1.0", features = ["rc"], optional = true }
+serde_derive = { version = "^1.0", optional = true }
+serde_json = { version = "^1.0", features = ["preserve_order"], optional = true }
 # compression of avro
 libflate = { version = "1.1.1", optional = true }
 snap = { version = "1", optional = true }
@@ -134,7 +135,7 @@ io_csv_async = ["io_csv_read_async"]
 io_csv_read = ["csv", "lexical-core"]
 io_csv_read_async = ["csv-async", "lexical-core", "futures"]
 io_csv_write = ["csv-core", "streaming-iterator", "lexical-core"]
-io_json = ["serde", "serde_json", "streaming-iterator", "fallible-streaming-iterator", "indexmap", "lexical-core"]
+io_json = ["json-deserializer", "streaming-iterator", "fallible-streaming-iterator", "indexmap", "lexical-core"]
 io_ipc = ["arrow-format"]
 io_ipc_write_async = ["io_ipc", "futures"]
 io_ipc_read_async = ["io_ipc", "futures", "async-stream"]
@@ -156,9 +157,9 @@ io_avro_compression = [
     "crc",
 ]
 io_avro_async = ["io_avro", "futures", "async-stream"]
-# io_json: its dependencies + error handling
+# serde+serde_json: its dependencies + error handling
 # serde_derive: there is some derive around
-io_json_integration = ["io_json", "serde_derive", "hex"]
+io_json_integration = ["hex", "serde", "serde_derive", "serde_json", "io_ipc"]
 io_print = ["comfy-table"]
 # the compute kernels. Disabling this significantly reduces compile time.
 compute_aggregate = ["multiversion"]
@@ -313,6 +314,10 @@ harness = false
 name = "write_json"
 harness = false
 
+[[bench]]
+name = "read_json"
+harness = false
+
 [[bench]]
 name = "slices_iterator"
 harness = false

benches/read_json.rs

@@ -0,0 +1,67 @@
+use arrow2::array::Array;
+use arrow2::datatypes::DataType;
+use criterion::{criterion_group, criterion_main, Criterion};
+
+use arrow2::io::json::{read, write};
+use arrow2::util::bench_util::*;
+
+fn prep(array: impl Array + 'static) -> (Vec<u8>, DataType) {
+    let mut data = vec![];
+    let blocks = write::Serializer::new(
+        vec![Ok(Box::new(array) as Box<dyn Array>)].into_iter(),
+        vec![],
+    );
+    // the operation of writing is IO-bounded.
+    write::write(&mut data, blocks).unwrap();
+
+    let value = read::json_deserializer::parse(&data).unwrap();
+
+    let dt = read::infer(&value).unwrap();
+    (data, dt)
+}
+
+fn bench_read(data: &[u8], dt: &DataType) {
+    let value = read::json_deserializer::parse(data).unwrap();
+    read::deserialize(&value, dt.clone()).unwrap();
+}
+
+fn add_benchmark(c: &mut Criterion) {
+    (10..=20).step_by(2).for_each(|log2_size| {
+        let size = 2usize.pow(log2_size);
+
+        let array = create_primitive_array::<i32>(size, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read i32 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_primitive_array::<f64>(size, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read f64 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_string_array::<i32>(size, 10, 0.1, 42);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read utf8 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+
+        let array = create_boolean_array(size, 0.1, 0.1);
+
+        let (data, dt) = prep(array);
+
+        c.bench_function(&format!("read bool 2^{}", log2_size), |b| {
+            b.iter(|| bench_read(&data, &dt))
+        });
+    })
+}
+
+criterion_group!(benches, add_benchmark);
+criterion_main!(benches);

examples/json_read.rs

@@ -1,18 +1,22 @@
-use std::fs::File;
-use std::io::BufReader;
+/// Example of reading a JSON file.
+use std::fs;
 use std::sync::Arc;
 
 use arrow2::array::Array;
 use arrow2::error::Result;
 use arrow2::io::json::read;
 
 fn read_path(path: &str) -> Result<Arc<dyn Array>> {
-    // Example of reading a JSON file.
-    let reader = BufReader::new(File::open(path)?);
-    let json = serde_json::from_reader(reader)?;
+    // read the file into memory (IO-bounded)
+    let data = fs::read(path)?;
 
+    // create a non-owning struct of the data (CPU-bounded)
+    let json = read::json_deserializer::parse(&data)?;
+
+    // use it to infer an Arrow schema (CPU-bounded)
     let data_type = read::infer(&json)?;
 
+    // and deserialize it (CPU-bounded)
     read::deserialize(&json, data_type)
 }
 

src/io/avro/read/decompress.rs

@@ -9,6 +9,7 @@ use super::super::{Block, CompressedBlock};
 use super::BlockStreamIterator;
 use super::Compression;
 
+#[cfg(feature = "io_avro_compression")]
 const CRC_TABLE: crc::Crc<u32> = crc::Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
 
 /// Decompresses an Avro block.

src/io/avro/write/compress.rs

@@ -5,6 +5,7 @@ use crate::error::Result;
 use super::Compression;
 use super::{Block, CompressedBlock};
 
+#[cfg(feature = "io_avro_compression")]
 const CRC_TABLE: crc::Crc<u32> = crc::Crc::<u32>::new(&crc::CRC_32_ISO_HDLC);
 
 /// Compresses a [`Block`] to a [`CompressedBlock`].

src/io/json/mod.rs

@@ -5,8 +5,8 @@ pub mod write;
 
 use crate::error::Error;
 
-impl From<serde_json::error::Error> for Error {
-    fn from(error: serde_json::error::Error) -> Self {
-        Error::External("".to_string(), Box::new(error))
+impl From<json_deserializer::Error> for Error {
+    fn from(error: json_deserializer::Error) -> Self {
+        Error::ExternalFormat(error.to_string())
     }
 }