一、虚拟线程核心优势

二、爬虫系统核心实现

1. 虚拟线程调度器配置

ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

// 自定义调度器参数
ExecutorService customExecutor = Executors.newThreadPerTaskExecutor(
    Thread.ofVirtual()
        .name("crawler-", 0)
        .scheduler(ForkJoinPool.commonPool())
        .factory()
);

2. 并发爬取任务封装

class CrawlerTask implements Runnable {
    private final String url;
    private final StorageService storage;

    public CrawlerTask(String url, StorageService storage) {
        this.url = url;
        this.storage = storage;
    }

    @Override
    public void run() {
        try (HttpClient client = HttpClient.newHttpClient()) {
            HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .timeout(Duration.ofSeconds(10))
                .build();

            HttpResponse response = client.send(
                request, HttpResponse.BodyHandlers.ofString()
            );

            if (response.statusCode() == 200) {
                List links = LinkParser.extractLinks(response.body());
                storage.save(new WebPage(url, response.body(), links));
            }
        } catch (Exception e) {
            System.err.println("Failed to crawl: " + url);
        }
    }
}

3. 任务分发与流量控制

class CrawlerEngine {
    private final ExecutorService executor;
    private final RateLimiter rateLimiter;
    private final Set visited = ConcurrentHashMap.newKeySet();

    public CrawlerEngine(int qps) {
        this.executor = Executors.newVirtualThreadPerTaskExecutor();
        this.rateLimiter = RateLimiter.create(qps);
    }

    public void crawl(List seeds) {
        seeds.forEach(this::submitTask);
        
        while (!allDone()) {
            Thread.sleep(1000);
        }
    }

    private void submitTask(String url) {
        if (visited.add(url)) {
            rateLimiter.acquire();
            executor.submit(new CrawlerTask(url, storage));
        }
    }
}

三、性能优化关键点

• 连接池管理：每个虚拟线程复用HTTP连接
• 内存控制：限制待处理队列大小
• 异常处理：避免单个任务崩溃影响全局
• 结果存储：异步批量写入提高IO效率

监控指标示例

// 获取虚拟线程状态
ThreadMXBean bean = ManagementFactory.getThreadMXBean();
System.out.println("Active threads: " + bean.getThreadCount());
System.out.println("Peak threads: " + bean.getPeakThreadCount());

四、与传统方案的对比测试