Improving Virtual Thread performance

Author: franz1981

frameworks/Java/netty/run_netty_loom.sh

@@ -10,6 +10,9 @@ JAVA_OPTIONS="--enable-native-access=ALL-UNNAMED \
   -Dio.netty.buffer.checkBounds=false \
   -Dio.netty.buffer.checkAccessible=false \
   -Dhello.eventloop.carrier=true \
+  -XX:+UnlockExperimentalVMOptions \
+  -XX:-DoJVMTIVirtualThreadTransitions \
+  -Djdk.trackAllThreads=false \
   $@"
 
 java $JAVA_OPTIONS -jar app.jar

frameworks/Java/netty/src/main/java/hello/HelloServerHandler.java

@@ -1,12 +1,9 @@
 package hello;
 
-import static hello.Constants.STATIC_PLAINTEXT;
-import static hello.Constants.newMsg;
 import static hello.HttpResponses.makeJsonResponse;
 import static hello.HttpResponses.makePlaintextResponse;
 import static hello.JsonUtils.acquireJsonStreamFromEventLoop;
 import static hello.JsonUtils.releaseJsonStreamFromEventLoop;
-import static hello.JsonUtils.serializeMsg;
 import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
 import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
 
@@ -17,7 +14,6 @@
 import java.util.concurrent.TimeUnit;
 
 import com.jsoniter.output.JsonStream;
-import com.jsoniter.output.JsonStreamPool;
 
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelFutureListener;

frameworks/Java/netty/src/main/java/hello/HelloWebServer.java

@@ -16,9 +16,21 @@
 public class HelloWebServer {
 
 	private static final boolean EVENT_LOOP_CARRIER = Boolean.getBoolean("hello.eventloop.carrier");
+	private static final IoMultiplexer PREFERRED_TRANSPORT;
 
 	static {
 		ResourceLeakDetector.setLevel(Level.DISABLED);
+		String transportName = System.getProperty("hello.transport");
+		if (transportName != null) {
+			try {
+				PREFERRED_TRANSPORT = IoMultiplexer.valueOf(transportName);
+			} catch (IllegalArgumentException e) {
+				System.err.println("Invalid transport name: " + transportName);
+				throw e;
+			}
+		} else {
+			PREFERRED_TRANSPORT = IoMultiplexer.type();
+		}
 	}
 
 	private final int port;
@@ -28,24 +40,24 @@ public HelloWebServer(int port) {
 	}
 
 	public void run() throws Exception {
-		final var type = IoMultiplexer.type();
-		System.out.printf("Using %s IoMultiplexer%n", type);
+		final var preferredTransport = PREFERRED_TRANSPORT;
+		System.out.printf("Using %s IoMultiplexer%n", preferredTransport);
 		final int coreCount = Runtime.getRuntime().availableProcessors();
 		final var group = EVENT_LOOP_CARRIER?
-				type.newVirtualEventExecutorGroup(coreCount) :
-				type.newEventLoopGroup(coreCount);
+				preferredTransport.newVirtualEventExecutorGroup(coreCount) :
+				preferredTransport.newEventLoopGroup(coreCount);
 		if (EVENT_LOOP_CARRIER) {
 			LoomSupport.checkSupported();
 			System.out.println("Using EventLoop optimized for Loom");
 		}
 		try {
-			final var serverChannelClass = type.serverChannelClass();
+			final var serverChannelClass = preferredTransport.serverChannelClass();
 			var inet = new InetSocketAddress(port);
 			var b = new ServerBootstrap();
 
 			b.option(ChannelOption.SO_BACKLOG, 8192);
 			b.option(ChannelOption.SO_REUSEADDR, true);
-			switch (type) {
+			switch (preferredTransport) {
 				case EPOLL:
 					b.option(EpollChannelOption.SO_REUSEPORT, true);
 					break;

frameworks/Java/netty/src/main/java/hello/JsonUtils.java

@@ -7,6 +7,7 @@
 
 import com.jsoniter.output.JsonStream;
 import com.jsoniter.output.JsonStreamPool;
+import com.jsoniter.spi.Config;
 import com.jsoniter.spi.JsonException;
 
 import io.netty.util.concurrent.FastThreadLocal;
@@ -35,7 +36,13 @@ private static void setIndentation(JsonStream stream, int value) {
    public static JsonStream acquireJsonStreamFromEventLoop() {
       var stream = JSON_STREAM.get();
       if (stream == null) {
-         stream = new JsonStream(null, 512);
+         stream = new JsonStream(null, 512) {
+            // this is to save virtual threads to use thread locals
+            @Override
+            public Config currentConfig() {
+               return Config.INSTANCE;
+            }
+         };
       } else {
          stream.reset(null);
          JSON_STREAM.set(null);

frameworks/Java/netty/src/main/java/hello/loom/LoomSupport.java

@@ -4,9 +4,6 @@
 import java.lang.invoke.MethodHandles;
 import java.lang.reflect.Field;
 import java.util.concurrent.Executor;
-import java.util.concurrent.ForkJoinPool;
-
-import io.netty.util.internal.PlatformDependent;
 
 public final class LoomSupport {
    private static final boolean SUPPORTED;