Spring循环引用-@Async注解启动报错分析
目录
一、问题描述
二、问题分析
1、情景1
2、情景2
3、分析
三、解决方法
四、结论
一、问题描述
Spring的bean相互引用下，并且其中一个bean含有异步注解@Async，启动可能会出现错误：
org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'bean1Service': Bean with name 'bean1Service' has been injected into other beans [bean2Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:638) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:531) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:923) ~[spring-context-5.3.2.jar:5.3.2]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:588) ~[spring-context-5.3.2.jar:5.3.2]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1309) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1298) [spring-boot-2.4.1.jar:2.4.1]
at com.lb.reference.ReferenceApplication.main(ReferenceApplication.java:12) [classes/:na]
二、问题分析
环境 ：jdk1.8.0_191 Springboot2.4.1
工具：eclipse 2021-09 (4.21.0)
项目：
4.0.0
lb
cycle-reference
0.0.1-SNAPSHOT
jar
cycle-reference
http://maven.apache.org
org.springframework.boot
spring-boot-starter-parent
2.4.1
UTF-8
junit
junit
test
org.springframework.boot
spring-boot-starter-web
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;
@EnableAsync
@SpringBootApplication
public class ReferenceApplication {
public static void main(String[] args) {
SpringApplication.run(ReferenceApplication.class, args);
}
}
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
@Service
public class Bean1Service {
@Autowired
private Bean2Service bean2;
@Async
public void bean1() {
bean2.bean2();
}
}
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class Bean2Service {
@Autowired
private Bean1Service bean;
public void bean2() {
bean.bean1();
}
}
1、情景1
com.lb.reference.service.Bean1Service有@Async
com.lb.reference.service.Bean2Service无@Async
启动报错
org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'bean1Service': Bean with name 'bean1Service' has been injected into other beans [bean2Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:638) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:531) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.2.jar:5.3.2]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:923) ~[spring-context-5.3.2.jar:5.3.2]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:588) ~[spring-context-5.3.2.jar:5.3.2]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:767) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1309) [spring-boot-2.4.1.jar:2.4.1]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1298) [spring-boot-2.4.1.jar:2.4.1]
at com.lb.reference.ReferenceApplication.main(ReferenceApplication.java:12) [classes/:na]
2、情景2
com.lb.reference.service.Bean1Service无@Async
com.lb.reference.service.Bean2Service有@Async
启动正常
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.4.1)
2021-12-17 21:52:47.449 INFO 8816 --- [ main] com.lb.reference.ReferenceApplication : Starting ReferenceApplication using Java 1.8.0_191 on DESKTOP-58VVQ1F with PID 8816 (D:\java\ws_1\cycle-reference\target\classes started by liangbo in D:\java\ws_1\cycle-reference)
2021-12-17 21:52:47.453 INFO 8816 --- [ main] com.lb.reference.ReferenceApplication : No active profile set, falling back to default profiles: default
2021-12-17 21:52:49.544 INFO 8816 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2021-12-17 21:52:49.560 INFO 8816 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2021-12-17 21:52:49.560 INFO 8816 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.41]
2021-12-17 21:52:49.665 INFO 8816 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2021-12-17 21:52:49.665 INFO 8816 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2148 ms
2021-12-17 21:52:50.167 INFO 8816 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2021-12-17 21:52:50.844 INFO 8816 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-12-17 21:52:50.861 INFO 8816 --- [ main] com.lb.reference.ReferenceApplication : Started ReferenceApplication in 3.937 seconds (JVM running for 4.66)
3、分析
（1）、bean初始化顺序：bean1Service、bean2Service
位置：org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons()
（2）、spring默认提前暴露bean引用（allowCircularReferences=true），bean1工厂类加入三级缓存singletonFactories
位置：org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.addSingletonFactory(String, ObjectFactory)
（3）、 bean1属性填充
位置：org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(String, RootBeanDefinition, Object[])
（4）、发现依赖bean2，从bean容器找，还没初始化，接着初始化bean2(getBean()获取bean，没有则初始化)
位置：org.springframework.beans.factory.support.AbstractBeanFactory.getBean(String)
（5）、bean2提前暴露引用，和bean1一致，加入工厂
（6）、bean2初始化完成后，填充到bean1属性，接着初始化bean1
（7）、bean1从二级缓存earlySingletonObjects获取提前暴露的bean1(刚才还是在三级缓存singletonFactories，为啥，现在在二级缓存earlySingletonObjects？这个是初始化bean2时，由于依赖bean1，在从bean容器获取bean1时，从三级缓存提升至二级缓存的，填充至bean2)
三级缓存提升至二级缓存
从二级缓存获取bean1
（8）、在initializeBean方法中生成异步代理对象（后置处理器org.springframework.scheduling.annotation.AsyncAnnotationBeanPostProcessor完成代理），原bean和代理对象是两个对象，前后bean版本不一致，故抛异常
三、解决方法
1、去除循环引用
2、含有@Async注解bean延迟生成，引用属性加@Lazy
2、修改属性org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.allowRawInjectionDespiteWrapping为true，跳过检查
四、结论
含有@Async注解先初始化，启动会报错