百万并发！Java虚拟线程源码大揭秘：高并发场景实战指南，性能飙升百倍

// 虚拟线程核心实现
final class VirtualThread extends BaseVirtualThread {
    private final Continuation cont;
    private final Runnable task;

    // 构造器
    VirtualThread(ThreadGroup group, Runnable task) {
        super(group, "VT-" + nextThreadNum());
        this.task = task;
        this.cont = new Continuation(this::runContinuation);
    }

    // 执行入口
    @Override
    public void run() {
        cont.run();
    }

    // 延续体执行逻辑
    private void runContinuation() {
        try {
            task.run();
        } finally {
            afterTask();
        }
    }

    // 阻塞时挂起
    void park() {
        cont.yield();
    }
}

// Spring Boot 3.x虚拟线程配置
@Configuration
public class VirtualThreadConfig {

    @Bean
    public TomcatProtocolHandlerCustomizer<?> protocolHandlerCustomizer() {
        return protocolHandler -> {
            protocolHandler.setExecutor(Executors.newVirtualThreadPerTaskExecutor());
        };
    }
}

// 订单服务Controller（同步代码风格）
@RestController
public class OrderController {

    // 虚拟线程处理每个请求
    @PostMapping("/order")
    public ResponseEntity<OrderResponse> createOrder(@RequestBody OrderRequest request) {
        // 1. 校验用户（虚拟线程可挂起）
        User user = userService.validateUser(request.getUserId());
        
        // 2. 并发检查库存（虚拟线程优化点）
        InventoryStatus status = checkInventoryConcurrently(request);
        
        // 3. 创建订单
        Order order = orderService.create(user, request);
        
        return ResponseEntity.ok(OrderResponse.success(order));
    }

    // 虚拟线程实现并发库存检查
    private InventoryStatus checkInventoryConcurrently(OrderRequest request) {
        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
            List<CompletableFuture<ItemStock>> futures = request.getItems()
                .stream()
                .map(item -> CompletableFuture.supplyAsync(
                    () -> inventoryService.checkStock(item), executor))
                .toList();
            
            return CompletableFuture.allOf(futures.toArray(CompletableFuture[]::new))
                .thenApply(v -> futures.stream()
                    .map(CompletableFuture::join)
                    .collect(Collectors.toList()))
                .join();
        }
    }
}

// ❌ 错误示例：synchronized导致线程固定
public class PaymentService {
    private double balance;
    
    public synchronized void processPayment(Order order) {
        // 阻塞操作导致载体线程被占用！
        paymentGateway.charge(order); // HTTP请求
        balance -= order.getAmount();
    }
}

// ✅ 正确方案：使用ReentrantLock
public class PaymentService {
    private final ReentrantLock lock = new ReentrantLock();
    
    public void processPayment(Order order) {
        lock.lock();
        try {
            paymentGateway.charge(order); // 虚拟线程可挂起
            balance -= order.getAmount();
        } finally {
            lock.unlock();
        }
    }
}

# 监控线程固定问题
java -Djdk.tracePinnedThreads=full -jar app.jar

// 避免在虚拟线程中使用大对象ThreadLocal
private static final ScopedValue<Connection> DB_CONN = 
    ScopedValue.newInstance();

public void handleRequest() {
    ScopedValue.where(DB_CONN, getConnection())
               .run(() -> businessLogic());
}

public class RiskControlService {
    
    public RiskResult evaluate(Transaction tx) {
        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
            // 并行执行风控检查
            var future1 = executor.submit(() -> blacklistService.check(tx));
            var future2 = executor.submit(() -> amlService.analyze(tx));
            var future3 = executor.submit(() -> creditService.score(tx));
            
            // 组合结果（同步等待时自动挂起）
            return new RiskResult(
                future1.get(),
                future2.get(),
                future3.get()
            );
        }
    }
}

# 虚拟线程调度器参数
jdk.virtualThreadScheduler.parallelism=200 # CPU核心数*2
jdk.virtualThreadScheduler.maxPoolSize=1000
jdk.virtualThreadScheduler.minRunnable=4

# 监控配置
jdk.traceVirtualThreadLocals=true # 跟踪ThreadLocal泄露

# 生成虚拟线程诊断报告
jcmd <pid> Thread.dump_to_file -format=json /path/to/dump.json

FROM eclipse-temurin:21-jdk
EXPOSE 8080
ENTRYPOINT ["java", "-XX:+EnableContainerSupport", 
           "-Djdk.virtualThreadScheduler.parallelism=$(nproc)",
           "-jar", "/app.jar"]