深入理解Java虚拟线程

// 传统线程池处理请求
ExecutorService executor = Executors.newFixedThreadPool(200);
 
void handleRequest(Request request) {
    executor.execute(() -> {
        // 线程在此阻塞等待数据库响应
        Result result = queryDatabase(request); 
        processResult(result);
    });
}

// 使用虚拟线程处理请求
void handleRequestVirtual(Request request) {
    Thread.startVirtualThread(() -> {
        Result result = queryDatabase(request);
        processResult(result);
    });
}

// 虚拟线程配置
@Bean
public TomcatProtocolHandlerCustomizer<?> protocolHandlerVirtualThreads() {
    return protocolHandler -> 
        protocolHandler.setExecutor(Executors.newVirtualThreadPerTaskExecutor());
}
 
// 模拟数据库阻塞操作
@GetMapping("/data")
public String fetchData() throws InterruptedException {
    Thread.sleep(1000); // 模拟I/O阻塞
    return "Data fetched";
}

synchronized(lock) {
    // 会阻塞载体线程
    doWork(); 
}

lock.lock();
try { doWork(); } 
finally { lock.unlock(); }

// 可能导致内存泄漏
ThreadLocal<User> userHolder = new ThreadLocal<>();

// CPU密集型任务应使用平台线程
CompletableFuture.supplyAsync(this::heavyComputation, 
     Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()));

# 查看虚拟线程状态
jcmd <pid> Thread.dump_to_file -format=json vthreads.json
 
# 异步分析工具
jfr configure --threaddump