feat(server): introduce ByteBufferPool and integrate into connection handlers for reduced allocation overhead

yyubin · yyubin · commit 72468165126e · 2025-10-27T03:10:15.000+09:00
- Added ByteBufferPool for efficient buffer reuse across server components
  - Supports configurable small(2KB), medium(8KB), and large(32KB) buffer pools
  - Thread-safe via ConcurrentLinkedQueue and capacity-limited to prevent leaks
  - Tracks allocation, acquisition, and release statistics for profiling
- Integrated ByteBufferPool into DefaultConnectionManager
  - Replaced per-connection temporary buffer allocation with pooled buffer
  - Reduced GC pressure from high-frequency accept operations
- Integrated ByteBufferPool into HttpConnectionHandler
  - Pooled 8KB read buffers per connection, released on close
  - Planned for pooled write buffer support via HttpUtils
- Updated HttpUtils to provide overload of createResponseBuffer(ResponseEntity, ByteBufferPool)
  - Enables response buffer creation using pooled ByteBuffer
  - Preserves backward compatibility with existing static utility calls
- Overall: significant reduction of ByteBuffer allocation rate and GC churn under high load
diff --git a/build.gradle b/build.gradle
@@ -11,7 +11,7 @@ java {
 }
 
 group = 'org.example'
-version = '1.0-SNAPSHOT'
+version = '1.1-SNAPSHOT'
 
 repositories {
     mavenCentral()
diff --git a/profile_gatling.sh b/profile_gatling.sh
@@ -0,0 +1,38 @@
+#!/bin/bash
+# Sprout 서버 부하테스트 + Async Profiler 통합 스크립트
+
+SERVER_PORT=8080
+DURATION=30
+ASYNC_PROFILER_HOME=/Users/mac/IdeaProjects/async-profiler/build
+SIMULATION_CLASS=benchmark.HelloWorldSimulation
+
+PID=$(lsof -i :$SERVER_PORT -t)
+if [ -z "$PID" ]; then
+  echo "서버가 실행 중이 아닙니다. 먼저 Sprout 서버를 실행하세요."
+  exit 1
+fi
+echo "Sprout 서버 PID = $PID"
+
+ASPROF="$ASYNC_PROFILER_HOME/bin/asprof"
+if [ ! -f "$ASPROF" ]; then
+  echo "asprof 실행 파일을 찾을 수 없습니다. 경로를 확인하세요."
+  exit 1
+fi
+
+echo "1) Gatling 부하테스트 시작..."
+./gradlew gatlingRun --simulation=benchmark.HelloWorldSimulation &
+GATLING_PID=$!
+
+sleep 3
+
+echo "2) Async Profiler로 $DURATION초간 프로파일링..."
+env DYLD_LIBRARY_PATH=$ASYNC_PROFILER_HOME/lib $ASPROF -d $DURATION -e cpu   -o flamegraph -f cpu-flamegraph.html   $PID
+env DYLD_LIBRARY_PATH=$ASYNC_PROFILER_HOME/lib $ASPROF -d $DURATION -e alloc -o flamegraph -f alloc-flamegraph.html $PID
+
+wait $GATLING_PID
+
+echo "완료! 결과 파일"
+echo " - cpu-flamegraph.html"
+echo " - alloc-flamegraph.html"
+open cpu-flamegraph.html
+open alloc-flamegraph.html
diff --git a/src/main/java/sprout/server/HttpUtils.java b/src/main/java/sprout/server/HttpUtils.java
@@ -227,4 +227,52 @@ public static ByteBuffer createResponseBuffer(ResponseEntity<?> res) {
 
         return buffer;
     }
+
+    public static ByteBuffer createResponseBuffer(ResponseEntity<?> res, ByteBufferPool pool) {
+        if (res == null) return null;
+
+        byte[] bodyBytes = res.getBody() != null
+                ? res.getBody().toString().getBytes(StandardCharsets.UTF_8)
+                : new byte[0];
+
+        StringBuilder header = new StringBuilder();
+        header.append("HTTP/1.1 ")
+                .append(res.getStatusCode().getCode())
+                .append(" ")
+                .append(res.getStatusCode().getMessage())
+                .append("\r\n");
+
+        header.append("Content-Type: ")
+                .append(res.getContentType())
+                .append("\r\n");
+
+        header.append("Content-Length: ")
+                .append(bodyBytes.length)
+                .append("\r\n");
+
+        header.append("Connection: keep-alive\r\n");
+        header.append("Keep-Alive: timeout=5, max=1000\r\n");
+
+        if (res.getHeaders() != null) {
+            for (Map.Entry<String, String> entry : res.getHeaders().entrySet()) {
+                header.append(entry.getKey())
+                        .append(": ")
+                        .append(entry.getValue())
+                        .append("\r\n");
+            }
+        }
+
+        header.append("\r\n");
+
+        byte[] headerBytes = header.toString().getBytes(StandardCharsets.UTF_8);
+        int totalSize = headerBytes.length + bodyBytes.length;
+
+        // 풀에서 버퍼 대여
+        ByteBuffer buffer = pool.acquire(totalSize);
+        buffer.put(headerBytes);
+        buffer.put(bodyBytes);
+        buffer.flip();
+        return buffer;
+    }
+
 }
diff --git a/src/main/java/sprout/server/builtins/DefaultConnectionManager.java b/src/main/java/sprout/server/builtins/DefaultConnectionManager.java
@@ -1,10 +1,7 @@
 package sprout.server.builtins;
 
 import sprout.beans.annotation.Component;
-import sprout.server.AcceptableProtocolHandler;
-import sprout.server.ConnectionManager;
-import sprout.server.ProtocolDetector;
-import sprout.server.ProtocolHandler;
+import sprout.server.*;
 
 import java.nio.ByteBuffer;
 import java.nio.channels.SelectionKey;
@@ -18,10 +15,12 @@ public class DefaultConnectionManager implements ConnectionManager {
 
     private final List<ProtocolDetector> detectors;
     private final List<ProtocolHandler> handlers;
+    private final ByteBufferPool bufferPool;
 
-    public DefaultConnectionManager(List<ProtocolDetector> detectors, List<ProtocolHandler> handlers) {
+    public DefaultConnectionManager(List<ProtocolDetector> detectors, List<ProtocolHandler> handlers, ByteBufferPool bufferPool) {
         this.detectors = detectors;
         this.handlers = handlers;
+        this.bufferPool = bufferPool;
     }
 
     @Override
@@ -30,10 +29,11 @@ public void acceptConnection(SelectionKey selectionKey, Selector selector) throw
         SocketChannel clientChannel = serverChannel.accept();
         clientChannel.configureBlocking(false);
 
-        ByteBuffer buffer = ByteBuffer.allocate(2048);
+        ByteBuffer buffer = bufferPool.acquire(ByteBufferPool.SMALL_BUFFER_SIZE);
         int bytesRead = clientChannel.read(buffer);
 
         if (bytesRead <= 0) {
+            bufferPool.release(buffer);
             clientChannel.close();
             return;
         }
@@ -54,6 +54,7 @@ public void acceptConnection(SelectionKey selectionKey, Selector selector) throw
 
         if ("UNKNOWN".equals(detectedProtocol) || detectedProtocol == null) {
             System.err.println("Unknown protocol detected. Closing socket: " + clientChannel.socket());
+            bufferPool.release(buffer);
             clientChannel.close();
             return;
         }
@@ -64,9 +65,10 @@ public void acceptConnection(SelectionKey selectionKey, Selector selector) throw
                     ((AcceptableProtocolHandler) handler).accept(clientChannel, selector, buffer);
                     return; // 핸들러를 찾았으므로 종료
                 }
-                break;
+
             }
         }
 
+        bufferPool.release(buffer);
     }
 }
diff --git a/src/main/java/sprout/server/builtins/HttpConnectionHandler.java b/src/main/java/sprout/server/builtins/HttpConnectionHandler.java
@@ -20,17 +20,22 @@ public class HttpConnectionHandler implements ReadableHandler, WritableHandler {
     private final RequestDispatcher dispatcher;
     private final HttpRequestParser parser;
     private final RequestExecutorService requestExecutorService;
+    private final ByteBufferPool bufferPool;
 
-    private final ByteBuffer readBuffer = ByteBuffer.allocate(8192);
+    private final ByteBuffer readBuffer;
     private volatile ByteBuffer writeBuffer;
     private HttpConnectionStatus currentState = HttpConnectionStatus.READING;
 
-    public HttpConnectionHandler(SocketChannel channel, Selector selector, RequestDispatcher dispatcher, HttpRequestParser parser, RequestExecutorService requestExecutorService, ByteBuffer initialBuffer) {
+    public HttpConnectionHandler(SocketChannel channel, Selector selector, RequestDispatcher dispatcher, HttpRequestParser parser, RequestExecutorService requestExecutorService, ByteBufferPool bufferPool, ByteBuffer initialBuffer) {
         this.channel = channel;
         this.selector = selector;
         this.dispatcher = dispatcher;
         this.parser = parser;
         this.requestExecutorService = requestExecutorService;
+        this.bufferPool = bufferPool;
+
+        // 버퍼 풀에서 8KB 버퍼 대여
+        this.readBuffer = bufferPool.acquire(ByteBufferPool.MEDIUM_BUFFER_SIZE);
 
         if (initialBuffer != null && initialBuffer.hasRemaining()) {
             this.readBuffer.put(initialBuffer);
@@ -43,6 +48,7 @@ public HttpConnectionHandler(SocketChannel channel, Selector selector, RequestDi
     public void read(SelectionKey key) throws Exception {
         System.out.println("Try to read from " + channel.socket() + " with current state: " + currentState + " and buffer size: " + readBuffer.remaining() + " bytes");
         if (currentState != HttpConnectionStatus.READING) return;
+
         System.out.println("Read from " + channel.socket() + " with current state: " + currentState + " and buffer size: " + readBuffer.remaining() + " bytes");
         int bytesRead = channel.read(readBuffer);
         if (bytesRead == -1) {
@@ -77,7 +83,7 @@ public void read(SelectionKey key) throws Exception {
                     dispatcher.dispatch(req, res);
 
                     // 5. 응답 준비 및 쓰기 상태 전환
-                    this.writeBuffer = HttpUtils.createResponseBuffer(res.getResponseEntity());
+                    this.writeBuffer = HttpUtils.createResponseBuffer(res.getResponseEntity(), bufferPool);
                     this.currentState = HttpConnectionStatus.WRITING;
 
                     // 6. Selector에 쓰기 이벤트 감지 요청
@@ -92,6 +98,9 @@ public void read(SelectionKey key) throws Exception {
 
             // 버퍼 초기화 (다음 요청을 위해)
             readBuffer.clear();
+        } else {
+            // 아직 요청이 완전하지 않으면 다음 read 대기
+            readBuffer.compact();
         }
 
     }
@@ -102,6 +111,11 @@ private void closeConnection(SelectionKey key) {
             channel.close();
         } catch (IOException e) {
             e.printStackTrace();
+        } finally {
+            bufferPool.release(readBuffer);
+            if (writeBuffer != null) {
+                bufferPool.release(writeBuffer);
+            }
         }
     }
 
@@ -114,6 +128,8 @@ public void write(SelectionKey key) throws IOException {
         if (!writeBuffer.hasRemaining()) {
             // 버퍼의 모든 데이터를 전송 완료
             this.currentState = HttpConnectionStatus.READING;
+
+            bufferPool.release(writeBuffer);
             this.writeBuffer = null;
 
             // keep-alive 지원: 다음 요청을 기다리기 위해 READ 모드로 전환
diff --git a/src/test/java/sprout/server/builtins/DefaultConnectionManagerTest.java b/src/test/java/sprout/server/builtins/DefaultConnectionManagerTest.java
@@ -7,6 +7,7 @@
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import sprout.server.AcceptableProtocolHandler;
+import sprout.server.ByteBufferPool;
 import sprout.server.ProtocolDetector;
 
 import java.nio.ByteBuffer;
@@ -37,12 +38,14 @@ class DefaultConnectionManagerTest {
     private ServerSocketChannel mockServerChannel;
     @Mock
     private SocketChannel mockClientChannel;
+    @Mock
+    private ByteBufferPool mockByteBufferPool;
 
     private DefaultConnectionManager connectionManager;
 
     @BeforeEach
     void setUp() {
-        connectionManager = new DefaultConnectionManager(List.of(mockDetector), List.of(mockHandler));
+        connectionManager = new DefaultConnectionManager(List.of(mockDetector), List.of(mockHandler), mockByteBufferPool);
     }
 
     @Test

Original file line number	Diff line number	Diff line change
`@@ -11,7 +11,7 @@ java {`
`11`	`11`	`}`
`12`	`12`
`13`	`13`	`group = 'org.example'`
`14`		`-version = '1.0-SNAPSHOT'`
	`14`	`+version = '1.1-SNAPSHOT'`
`15`	`15`
`16`	`16`	`repositories {`
`17`	`17`	`mavenCentral()`