Spring Boot @Async嵌套调用不生效问题排查

问题场景 #

已通过@EnableAsync开启Spring异步支持，自定义了前缀为ASYNC-的线程池，@Async注解在@RestController中能正常触发异步执行，但在服务内部嵌套调用BatchLogGateway#writeBatchLog()方法时，INSERT操作始终在原线程执行，日志中看不到自定义的异步线程编号。

核心原因 #

Spring的@Async依赖动态代理实现，只有通过Spring容器生成的代理对象调用方法时，异步增强逻辑才会生效。如果在服务内部直接调用自身的@Async方法（绕过代理），会直接执行原始方法，无法触发异步。

解决方案 #

1. 通过Spring容器获取代理对象调用 #

在服务类中注入ApplicationContext，通过容器获取自身的代理实例，再用代理对象调用异步方法：

@Service
public class BatchLogGateway {
    @Autowired
    private NamedParameterJdbcTemplate jdbcTemplate;
    @Autowired
    private ApplicationContext applicationContext;
    private static final Logger logger = LoggerFactory.getLogger(BatchLogGateway.class);

    @Async
    public void writeBatchLog(int batchNo, String errorTxt) {
        MapSqlParameterSource namedParameters = new MapSqlParameterSource();
        namedParameters.addValue("batchNo", batchNo);
        namedParameters.addValue("error", errorTxt);
        try {
            jdbcTemplate.update("INSERT INTO batches_error_log (error_log, batch_no) values (:error, :batchNo)", namedParameters);
        } catch (Exception e) {
            logger.error("writing into batchLog {} was unsuccessful", batchNo);
        }
    }

    // 内部调用时使用此方法
    public void triggerWriteBatchLog(int batchNo, String errorTxt) {
        BatchLogGateway proxy = applicationContext.getBean(BatchLogGateway.class);
        proxy.writeBatchLog(batchNo, errorTxt);
    }
}

内部调用时，调用triggerWriteBatchLog而非直接调用writeBatchLog，即可触发异步逻辑。

2. 拆分异步方法到独立服务类 #

将writeBatchLog方法迁移到独立的服务类中，比如BatchLogAsyncService：

@Service
public class BatchLogAsyncService {
    @Autowired
    private NamedParameterJdbcTemplate jdbcTemplate;
    private static final Logger logger = LoggerFactory.getLogger(BatchLogAsyncService.class);

    @Async
    public void writeBatchLog(int batchNo, String errorTxt) {
        MapSqlParameterSource namedParameters = new MapSqlParameterSource();
        namedParameters.addValue("batchNo", batchNo);
        namedParameters.addValue("error", errorTxt);
        try {
            jdbcTemplate.update("INSERT INTO batches_error_log (error_log, batch_no) values (:error, :batchNo)", namedParameters);
        } catch (Exception e) {
            logger.error("writing into batchLog {} was unsuccessful", batchNo);
        }
    }
}

然后在原服务类中注入这个新服务，通过代理对象调用：

@Service
public class BatchLogGateway {
    @Autowired
    private BatchLogAsyncService batchLogAsyncService;

    public void someInternalMethod(int batchNo, String errorTxt) {
        batchLogAsyncService.writeBatchLog(batchNo, errorTxt);
    }
}

3. 利用AopContext获取当前代理 #

先修改配置类，开启暴露代理：

@Configuration
@EnableAsync
@EnableAspectJAutoProxy(exposeProxy = true)
public class ThreadConfig {
    @Bean
    public Executor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(60);
        executor.setMaxPoolSize(200);
        executor.setThreadNamePrefix("ASYNC-");
        executor.initialize();
        return executor;
    }
}

然后在服务内部调用时，通过AopContext获取代理对象：

@Service
public class BatchLogGateway {
    @Autowired
    private NamedParameterJdbcTemplate jdbcTemplate;
    private static final Logger logger = LoggerFactory.getLogger(BatchLogGateway.class);

    public void someInternalMethod(int batchNo, String errorTxt) {
        BatchLogGateway proxy = (BatchLogGateway) AopContext.currentProxy();
        proxy.writeBatchLog(batchNo, errorTxt);
    }

    @Async
    public void writeBatchLog(int batchNo, String errorTxt) {
        MapSqlParameterSource namedParameters = new MapSqlParameterSource();
        namedParameters.addValue("batchNo", batchNo);
        namedParameters.addValue("error", errorTxt);
        try {
            jdbcTemplate.update("INSERT INTO batches_error_log (error_log, batch_no) values (:error, :batchNo)", namedParameters);
        } catch (Exception e) {
            logger.error("writing into batchLog {} was unsuccessful", batchNo);
        }
    }
}

验证 #

执行后查看日志，若出现ASYNC-前缀的线程名，说明异步逻辑已生效。

内容的提问来源于stack exchange，提问作者Triffids