first version

.gitignore

@@ -1,2 +1,4 @@
 .idea
 .gradle
+build
+profilers

README.md

@@ -1 +1,67 @@
-# simdjson-java
+# simdjson-java
+
+A Java version of [simdjson](https://github.com/simdjson/simdjson) - a JSON parser using SIMD instructions,
+based on the paper [Parsing Gigabytes of JSON per Second](https://arxiv.org/abs/1902.08318) 
+by Geoff Langdale and Daniel Lemire.
+
+This implementation is still missing several features available in simdsjon. For example:
+
+* Support for Unicode characters
+* UTF-8 validation
+* Full support for parsing floats
+* Support for 512-bit vectors
+
+## Code Sample
+
+```java
+byte[] json = loadTwitterJson();
+
+SimdJsonParser parser = new SimdJsonParser();
+JsonValue jsonValue = simdJsonParser.parse(json, json.length);
+Iterator<JsonValue> tweets = jsonValue.get("statuses").arrayIterator();
+while (tweets.hasNext()) {
+    JsonValue tweet = tweets.next();
+    JsonValue user = tweet.get("user");
+    if (user.get("default_profile").asBoolean()) {
+        System.out.println(user.get("screen_name").asString());
+    }
+}
+```
+
+## Benchmarks
+
+To run the JMH benchmarks, execute the following command:
+
+```./gradlew jmh```
+
+## Tests
+
+To run the tests, execute the following command:
+
+```./gradlew test```
+
+## Performance
+
+This section presents a performance comparison of different JSON parsers available as Java libraries. The benchmark used 
+the [twitter.json](src/jmh/resources/twitter.json) dataset, and its goal was to measure the throughput (ops/s) of parsing 
+and finding all unique users with a default profile.
+
+**Note that simdjson-java is still missing several features (mentioned in the introduction), so the following results
+may not reflect its real performance.**
+
+Environment:
+* CPU: Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz
+* OS: Ubuntu 23.04, kernel 6.2.0-23-generic
+* Java: OpenJDK 64-Bit Server VM Temurin-20.0.1+9
+
+ Library                                           | Version | Throughput (ops/s) 
+---------------------------------------------------|---------|--------------------
+ simdjson-java                                     | -       | 1450.951           
+ simdjson-java (padded)                            | -       | 1505.227           
+ [jackson](https://github.com/FasterXML/jackson)   | 2.15.2  | 504.562            
+ [fastjson2](https://github.com/alibaba/fastjson)  | 2.0.35  | 590.743            
+ [jsoniter](https://github.com/json-iterator/java) | 0.9.23  | 384.664            
+
+To reproduce the benchmark results, execute the following command:
+
+```./gradlew jmh -Pjmh.includes='.*ParseAndSelectBenchmark.*'```

build.gradle

@@ -1,10 +1,13 @@
+import me.champeau.jmh.JmhBytecodeGeneratorTask
+import org.gradle.internal.os.OperatingSystem
+
 plugins {
     id 'java'
     id 'me.champeau.jmh' version '0.7.1'
 }
 
 group = 'com.github.piotrrzysko'
-version = '1.0-SNAPSHOT'
+version = '0.0.1-SNAPSHOT'
 
 repositories {
     mavenCentral()
@@ -21,6 +24,10 @@ ext {
 }
 
 dependencies {
+    jmhImplementation group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.15.2'
+    jmhImplementation group: 'com.alibaba.fastjson2', name: 'fastjson2', version: '2.0.35'
+    jmhImplementation group: 'com.jsoniter', name: 'jsoniter', version: '0.9.23'
+
     testImplementation group: 'org.assertj', name: 'assertj-core', version: '3.24.2'
     testImplementation group: 'org.junit.jupiter', name: 'junit-jupiter-api', version: junitVersion
     testImplementation group: 'org.junit.jupiter', name: 'junit-jupiter-params', version: junitVersion
@@ -29,4 +36,55 @@ dependencies {
 
 test {
     useJUnitPlatform()
+    jvmArgs += [
+            '--add-modules', 'jdk.incubator.vector',
+            '-Xmx2g'
+    ]
+}
+
+tasks.withType(JmhBytecodeGeneratorTask).configureEach {
+    jvmArgs.set(["--add-modules=jdk.incubator.vector"])
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.compilerArgs.add("--add-modules=jdk.incubator.vector")
+}
+
+compileTestJava {
+    options.compilerArgs += [
+            '--add-modules', 'jdk.incubator.vector'
+    ]
+}
+
+jmh {
+    fork = 1
+    warmupIterations = 3
+    iterations = 5
+    jvmArgsPrepend = [
+            '--add-modules=jdk.incubator.vector'
+    ]
+    if (getBooleanProperty('jmh.profilersEnabled', false)) {
+        if (OperatingSystem.current().isLinux()) {
+            profilers = [
+                    'perf',
+                    'perfasm:intelSyntax=true',
+                    'async:verbose=true;output=flamegraph;event=cpu;dir=./profilers/async;libPath=' + getAsyncProfilerLibPath('LD_LIBRARY_PATH')
+            ]
+        } else if (OperatingSystem.current().isMacOsX()) {
+            profilers = [
+                    'async:verbose=true;output=flamegraph;event=cpu;dir=./profilers/async;libPath=' + getAsyncProfilerLibPath('DYLD_LIBRARY_PATH')
+            ]
+        }
+    }
+    if (project.hasProperty('jmh.includes')) {
+        includes = [project.findProperty('jmh.includes')]
+    }
+}
+
+def getBooleanProperty(String name, boolean defaultValue) {
+    Boolean.valueOf((project.findProperty(name) ?: defaultValue) as String)
+}
+
+static def getAsyncProfilerLibPath(String envVarName) {
+    System.getenv(envVarName) ?: System.getProperty('java.library.path')
 }

src/jmh/java/com/github/piotrrzysko/simdjson/ParseAndSelectBenchmark.java

@@ -0,0 +1,118 @@
+package com.github.piotrrzysko.simdjson;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONObject;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.jsoniter.JsonIterator;
+import com.jsoniter.any.Any;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+
+import static com.github.piotrrzysko.simdjson.SimdJsonPaddingUtil.padded;
+
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.SECONDS)
+public class ParseAndSelectBenchmark {
+
+    private final SimdJsonParser simdJsonParser = new SimdJsonParser();
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    private byte[] buffer;
+    private byte[] bufferPadded;
+
+    @Setup(Level.Trial)
+    public void setup() throws IOException {
+        try (InputStream is = ParseBenchmark.class.getResourceAsStream("/twitter.json")) {
+            buffer = is.readAllBytes();
+            bufferPadded = padded(buffer);
+        }
+    }
+
+    @Benchmark
+    public int countUniqueUsersWithDefaultProfile_jackson() throws IOException {
+        JsonNode jacksonJsonNode = objectMapper.readTree(buffer);
+        Set<String> defaultUsers = new HashSet<>();
+        Iterator<JsonNode> tweets = jacksonJsonNode.get("statuses").elements();
+        while (tweets.hasNext()) {
+            JsonNode tweet = tweets.next();
+            JsonNode user = tweet.get("user");
+            if (user.get("default_profile").asBoolean()) {
+                defaultUsers.add(user.get("screen_name").textValue());
+            }
+        }
+        return defaultUsers.size();
+    }
+
+    @Benchmark
+    public int countUniqueUsersWithDefaultProfile_fastjson() {
+        JSONObject jsonObject = (JSONObject) JSON.parse(buffer);
+        Set<String> defaultUsers = new HashSet<>();
+        Iterator<Object> tweets = jsonObject.getJSONArray("statuses").iterator();
+        while (tweets.hasNext()) {
+            JSONObject tweet = (JSONObject) tweets.next();
+            JSONObject user = (JSONObject) tweet.get("user");
+            if (user.getBoolean("default_profile")) {
+                defaultUsers.add(user.getString("screen_name"));
+            }
+        }
+        return defaultUsers.size();
+    }
+
+    @Benchmark
+    public int countUniqueUsersWithDefaultProfile_jsoniter() {
+        Any json = JsonIterator.deserialize(buffer);
+        Set<String> defaultUsers = new HashSet<>();
+        for (Any tweet : json.get("statuses")) {
+            Any user = tweet.get("user");
+            if (user.get("default_profile").toBoolean()) {
+                defaultUsers.add(user.get("screen_name").toString());
+            }
+        }
+        return defaultUsers.size();
+    }
+
+    @Benchmark
+    public int countUniqueUsersWithDefaultProfile_simdjson() {
+        JsonValue simdJsonValue = simdJsonParser.parse(buffer, buffer.length);
+        Set<String> defaultUsers = new HashSet<>();
+        Iterator<JsonValue> tweets = simdJsonValue.get("statuses").arrayIterator();
+        while (tweets.hasNext()) {
+            JsonValue tweet = tweets.next();
+            JsonValue user = tweet.get("user");
+            if (user.get("default_profile").asBoolean()) {
+                defaultUsers.add(user.get("screen_name").asString());
+            }
+        }
+        return defaultUsers.size();
+    }
+
+    @Benchmark
+    public int countUniqueUsersWithDefaultProfile_simdjsonPadded() {
+        JsonValue simdJsonValue = simdJsonParser.parse(bufferPadded, buffer.length);
+        Set<String> defaultUsers = new HashSet<>();
+        Iterator<JsonValue> tweets = simdJsonValue.get("statuses").arrayIterator();
+        while (tweets.hasNext()) {
+            JsonValue tweet = tweets.next();
+            JsonValue user = tweet.get("user");
+            if (user.get("default_profile").asBoolean()) {
+                defaultUsers.add(user.get("screen_name").asString());
+            }
+        }
+        return defaultUsers.size();
+    }
+}

src/jmh/java/com/github/piotrrzysko/simdjson/ParseBenchmark.java

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+package com.github.piotrrzysko.simdjson;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.TimeUnit;
+
+import static com.github.piotrrzysko.simdjson.SimdJsonPaddingUtil.padded;
+
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.SECONDS)
+public class ParseBenchmark {
+
+    @Param({"/twitter.json" /*, "/gsoc-2018.json - unicode is not supported yet"*/, "/github_events.json"})
+    String fileName;
+
+    private final SimdJsonParser simdJsonParser = new SimdJsonParser();
+
+    private byte[] buffer;
+    private byte[] bufferPadded;
+
+    @Setup(Level.Trial)
+    public void setup() throws IOException {
+        try (InputStream is = ParseBenchmark.class.getResourceAsStream(fileName)) {
+            buffer = is.readAllBytes();
+            bufferPadded = padded(buffer);
+        }
+    }
+
+    @Benchmark
+    public JsonValue simdjson() {
+        return simdJsonParser.parse(buffer, buffer.length);
+    }
+
+    @Benchmark
+    public JsonValue simdjsonPadded() {
+        return simdJsonParser.parse(bufferPadded, buffer.length);
+    }
+}

src/jmh/java/com/github/piotrrzysko/simdjson/SimdJsonPaddingUtil.java

@@ -0,0 +1,10 @@
+package com.github.piotrrzysko.simdjson;
+
+class SimdJsonPaddingUtil {
+
+    static byte[] padded(byte[] src) {
+        byte[] bufferPadded = new byte[src.length + 64];
+        System.arraycopy(src, 0, bufferPadded, 0, src.length);
+        return bufferPadded;
+    }
+}