lilac

Building a Minimal HTTP Server with Virtual Threads in Java

In the latest release of JDK 21, virtual threads have become a stable feature, revolutionizing the way we write concurrent programs in Java. With virtual threads, it is now easier than ever to create highly performant and scalable applications. In this blog post, we will explore how to build a minimal yet fully functional HTTP server from scratch using virtual threads.

Introduction to Virtual Threads

Virtual threads, also known as fibers, are lightweight threads that can be scheduled cooperatively by the JVM. Unlike traditional threads, which are managed by the operating system, virtual threads are managed at the application level, resulting in reduced overhead and improved scalability. By leveraging virtual threads, we can achieve higher concurrency without the need for complex thread management.

Setting Up the Project

Install Tailscale

Install go if it's not there.

Install tailscale commands.

go install tailscale.com/cmd/[email protected]
go install tailscale.com/cmd/[email protected]

Install service

Since this linux is an old version, it still use sysv scripts for service management. To run tailscaled as a daemon (service), follow the procedure below.

Playground

Install wazero with the following commmand.

go get github.com/tetratelabs/wazero@latest

Download the wasm file of a Javascript interpreter. For simplicity, the following ways are listed.
- If you have wapm installed, you could download one with

Build a persistent, high availability and low latency key-value storage engine for derived data. One of such use cases is feature store. These use cases share some common characteristics, that we could utililze to build a better performing database.

The data is derived, so no need to handle replication or data recovery.
All the writes are through bulk loading, so no concurrency control needed.

In summary, it's like a scalable cache engine.

Features

High throughput bulk load

Prerequisites

Install graalvm.

sdk install java 22.3.r19-grl

Change current JVM to graalvm.

sdk use java 22.3.r19-grl

Install Graal js following the guide.

	apiVersion: apps/v1
	kind: Deployment
	metadata:
	name: coder
	spec:
	replicas: 1
	strategy:
	type: Recreate
	template:
	spec:

	.phony: run

	run: thread.wasm
	wasmtime run --wasm-features threads --wasi-modules experimental-wasi-threads ./thread.wasm

	thread.wasm: thread.wat
	wat2wasm --debug-names --enable-threads thread.wat

	# builtin functions

	# graph is a builtin module exposed by the host environment
	# graph.nodes = {}
	# graph.edges = []


	def node(name, operation, conf={}, predicate=None):
	"""
	:rtype: str the node name is returned

	package example

	import com.google.common.collect.{ImmutableCollection, ImmutableList, ImmutableMap}
	import net.starlark.java.annot.{Param, StarlarkBuiltin, StarlarkMethod}
	import net.starlark.java.eval.{Dict, EvalException, Module, Mutability, Starlark, StarlarkFunction, StarlarkInt, StarlarkList, StarlarkSemantics, StarlarkThread, Structure, Tuple}
	import net.starlark.java.syntax.{FileOptions, ParserInput}

	import scala.collection.mutable.ListBuffer

	object StarlarkDemo extends App {

	public class HelloWorld {

	public static void main(String[] args) {
	System.out.println("Hello, World!");
	}
	}