JVM JSON byte-array format measurements

This comparison covers numeric byte arrays and Base16 strings on the unchanged jsoniter-scala ArrayOfBytesReading, ArrayOfBytesWriting, Base16Reading, and Base16Writing workloads at size=512. Higher throughput is better.

All 12 final adjacent comparison pairs exceed 10%. Numeric-array reading has a narrow margin: its smallest measured improvement is 10.05%. These are local steady-state measurements, not a guarantee for other sizes, data distributions, machines, or JVMs.

Results

Workload	jsoniter-scala median, ops/s	Fory median, ops/s	Median paired improvement	Paired range
Numeric byte-array reading	646,911	713,856	+10.18%	+10.05% to +11.55%
Numeric byte-array writing	1,539,685	3,350,581	+117.93%	+116.07% to +118.36%
Base16 reading	2,914,929	3,585,325	+22.18%	+15.26% to +24.77%
Base16 writing	8,444,372	9,639,286	+15.94%	+13.78% to +16.00%

Each pair compares the means of five measurement iterations. The improvement column is the median of those paired ratios, not the ratio of independent medians. All final samples are retained. Earlier, shorter numeric-reading comparisons measured +8.59% and +13.01%; they are also included in the evidence and illustrate why the final narrow margin should not be generalized.

Allocation per operation is approximately 528 B for Fory numeric-array reading and 1,128 B for jsoniter-scala. Both libraries allocate about 1,888 B for numeric array output, 528 B for Base16 input, and 1,048 B for Base16 output. Both use APIs that return independent arrays; neither uses the preallocated-output benchmark. Startup and retained lookup-table memory are outside these steady-state allocation figures. Fory's Base16 output table occupies 256 KiB after its first use.

The affected integer-reading path was also compared with the pre-optimization Fory revision in two adjacent pairs. Changes were +1.41% and +1.01%, within the range normally treated as noise; no regression was observed in those runs.

Iteration samples, allocations, paired results, and artifact hashes are available as JSON.

Workloads and configuration

The input bytes are the benchmark's original sequence (1 to size).map(_.toByte).toArray. Numeric arrays keep the original signed decimal JSON representation. Base16 keeps the original lowercase hexadecimal string. Models, inputs, expected outputs, and jsoniter-scala implementations are unchanged. Only the missing Fory adapters and their existing correctness specs are enabled.

Fory uses separate instances configured through its public builder:

import org.apache.fory.json.ForyJson;
import org.apache.fory.json.annotation.JsonByteArray;

ForyJson arrays = ForyJson.builder().byteArrayFormat(JsonByteArray.Format.ARRAY).build();
ForyJson hex = ForyJson.builder().byteArrayFormat(JsonByteArray.Format.BASE16).build();

Each reading adapter calls fromJson(jsonBytes, classOf[Array[Byte]]); each writing adapter calls toJsonBytes(obj). These configurations also apply to nested byte arrays; they are not benchmark-specific codecs.

Environment and revisions

• Date: September 21, 2026.
• Apple M4 Pro, 12 logical CPUs, 48 GiB RAM; macOS 15.7.2 arm64.
• OpenJDK 25.0.3; JMH 1.37.
• Fory: 13739263ebf31af5fc962184aaccf2833f8ffc9a, version 1.8.0-SNAPSHOT.
• Fory pre-optimization baseline: e1d2f9d67800901392755b1133968d448ab076b8.
• jsoniter-scala: 2.40.2-SNAPSHOT, checkout 71b2ba16f1d5261e2be4e98d5dfe4be452d0e136; its Fory adapter additions are based on 84cb277f2c2a16b4018bc61fdeec3eed62252a1e.
• Benchmark Scala: 3.9.0; Fory JSON Scala: 3.3.8.
• One thread and one fork per run; three 1-second warmups and five 1-second measurements; -Xms1g -Xmx1g -XX:+UseParallelGC; JMH GC profiler.
• Three adjacent pairs per workload. Order is jsoniter/Fory, Fory/jsoniter, jsoniter/Fory. Runs are serial; normal desktop background activity remains.

The runtime, core, Scala, and benchmark jars are frozen during measurement. Only the Fory JSON runtime jar changes in baseline/current controls.

Reproduction

Install Fory core, JSON, and JSON Scala artifacts before building the benchmark assembly. Enable Maven Local when using locally published snapshots:

sbt --java-home "$JAVA_HOME" \
  'set ThisBuild / resolvers += Resolver.mavenLocal' \
  '++3.9.0!' 'jsoniter-scala-benchmarkJVM/assembly'

Run each method as a separate process, alternating the library order between pairs. Use the same frozen classpath for both methods:

java -cp "$FORY_JSON_JAR:$FORY_SCALA_JAR:$FORY_CORE_JAR:$BENCHMARK_JAR" \
  org.openjdk.jmh.Main ".*\.${CASE}\.${METHOD}$" \
  -t 1 -f 1 -wi 3 -i 5 -w 1s -r 1s -p size=512 \
  -jvmArgs '-Xms1g -Xmx1g -XX:+UseParallelGC' -foe true -prof gc \
  -rf json -rff "$RESULT_FILE"

CASE is one of the four workload names above; METHOD is fory or jsoniterScala. No GraalVM or native-image performance is measured here.