新冠肺炎疫情最新公布东莞seo优化排名
以下是 Spring 中线程高级用法的详细说明，涵盖复杂场景的线程池管理、任务编排、线程上下文传递及性能优化：
1. 动态线程池配置
通过 ThreadPoolTaskExecutor 实现运行时动态调整参数（需配合监控系统如 Prometheus）。
@Bean("dynamicExecutor")
public ThreadPoolTaskExecutor dynamicExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(5);executor.setMaxPoolSize(20);executor.setQueueCapacity(100);executor.setThreadNamePrefix("Dynamic-");executor.setAllowCoreThreadTimeOut(true); // 允许核心线程超时回收executor.setKeepAliveSeconds(60); // 非核心线程空闲存活时间executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());executor.initialize();return executor;
}// 动态调整线程池参数
@Autowired
private ThreadPoolTaskExecutor dynamicExecutor;public void adjustPoolSize(int coreSize, int maxSize) {dynamicExecutor.setCorePoolSize(coreSize);dynamicExecutor.setMaxPoolSize(maxSize);dynamicExecutor.setKeepAliveSeconds(30);
}2. 复杂任务编排
使用 CompletableFuture 实现多任务并行执行和结果聚合。
@Async("dynamicExecutor")
public CompletableFuture<String> fetchUserData(Long userId) {// 模拟远程调用return CompletableFuture.completedFuture("User-" + userId);
}@Async("dynamicExecutor")
public CompletableFuture<String> fetchOrderData(Long userId) {// 模拟远程调用return CompletableFuture.completedFuture("Order-" + userId);
}// 合并两个异步任务结果
public CompletableFuture<Map<String, String>> getUserInfo(Long userId) {CompletableFuture<String> userFuture = fetchUserData(userId);CompletableFuture<String> orderFuture = fetchOrderData(userId);return userFuture.thenCombine(orderFuture, (user, order) -> {Map<String, String> result = new HashMap<>();result.put("user", user);result.put("order", order);return result;}).exceptionally(ex -> {// 统一异常处理return Collections.singletonMap("error", ex.getMessage());});
}3. 线程上下文传递
处理跨线程的上下文信息（如安全上下文、Trace ID）。
方案一：使用 TaskDecorator
@Bean("contextAwareExecutor")
public ThreadPoolTaskExecutor contextAwareExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(5);executor.setTaskDecorator(new ContextCopyingDecorator());executor.initialize();return executor;
}// 自定义装饰器复制上下文
public static class ContextCopyingDecorator implements TaskDecorator {@Overridepublic Runnable decorate(Runnable runnable) {// 获取父线程上下文（如 SecurityContext、MDC）SecurityContext context = SecurityContextHolder.getContext();Map<String, String> mdc = MDC.getCopyOfContextMap();return () -> {try {// 将上下文设置到子线程SecurityContextHolder.setContext(context);if (mdc != null) MDC.setContextMap(mdc);runnable.run();} finally {// 清理子线程上下文SecurityContextHolder.clearContext();MDC.clear();}};}
}方案二：使用 ThreadLocal + AOP
// 定义线程局部变量
private static final ThreadLocal<User> currentUser = new ThreadLocal<>();// 通过切面自动传递
@Aspect
@Component
public class ThreadLocalAspect {@Around("@annotation(org.springframework.scheduling.annotation.Async)")public Object propagateThreadLocal(ProceedingJoinPoint pjp) throws Throwable {User user = currentUser.get();return CompletableFuture.runAsync(() -> {try {currentUser.set(user);pjp.proceed();} finally {currentUser.remove();}});}
}4. 响应式线程池整合
与 WebFlux 或 Reactor 配合使用 Schedulers。
// 配置 Reactor 调度器
@Bean
public Scheduler boundedElasticScheduler() {return Schedulers.newBoundedElastic(50, // 线程数上限100, // 任务队列容量"reactor-scheduler");
}// 在 Service 中使用
public Mono<String> reactiveTask() {return Mono.fromCallable(() -> {// 阻塞操作（自动切换到指定调度器）return "Result from " + Thread.currentThread().getName();}).subscribeOn(boundedElasticScheduler());
}5. 线程池监控与管理
通过 Actuator 或自定义监控暴露线程池指标。
注册线程池指标
@Bean
public MeterBinder taskExecutorMetrics(ThreadPoolTaskExecutor executor) {return (registry) -> {ThreadPoolExecutor pool = executor.getThreadPoolExecutor();Gauge.builder("thread.pool.active", pool::getActiveCount).register(registry);Gauge.builder("thread.pool.queue.size", () -> pool.getQueue().size()).register(registry);};
}通过 JMX 管理
@Bean
public ThreadPoolTaskExecutor jmxExecutor() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(5);executor.setThreadNamePrefix("JMX-");executor.setBeanName("jmxThreadPool"); // 暴露为 MBeanexecutor.initialize();return executor;
}6. 高级异常处理
结合全局异常处理器和熔断机制。
// 自定义 Async 异常处理器
@Bean
public AsyncUncaughtExceptionHandler asyncExceptionHandler() {return (ex, method, params) -> {// 发送报警或记录详细日志log.error("Async method '{}' failed: {}", method.getName(), ex.getMessage());// 结合熔断器（如 Resilience4j）CircuitBreakerRegistry.ofDefaults().circuitBreaker(method.getName()).onError(ex.getCause());};
}// 在配置类中注册
@Configuration
public class AsyncConfig implements AsyncConfigurer {@Overridepublic AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {return asyncExceptionHandler();}
}7. 性能优化技巧
-
避免线程饥饿：为不同任务类型分配独立线程池（如 IO 密集型 vs CPU 密集型）
-
合理设置队列容量：根据任务特点选择
LinkedBlockingQueue或SynchronousQueue -
使用
@Async的限定符：为不同场景指定不同线程池
@Async("ioTaskExecutor")
public void ioIntensiveTask() { ... }@Async("cpuTaskExecutor")
public void cpuIntensiveTask() { ... }关闭线程池：在应用关闭时主动回收资源
@PreDestroy
public void destroy() {dynamicExecutor.shutdown();
}总结
Spring 线程高级用法需要关注以下核心问题：
1、线程池精细化控制：动态调整、资源隔离、队列策略
2、上下文一致性：安全、日志跟踪、事务的跨线程传递
3、系统可观测性：指标监控、异常追踪、熔断降级
4、性能与稳定性平衡：避免阻塞、死锁、资源泄漏