spring cloud gateway openfeign 联合使用产生死锁问题

spring cloud gateway openfeign 联合使用产生死锁问题，应用启动的时候阻塞卡住。

spring.cloud 版本如下

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>2020.0.4</version><type>pom</type><scope>import</scope>
</dependency>

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

java启动代码

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class GatewayApplication {public static void main(String[] args) {SpringApplication.run(GatewayApplication.class, args);}}

##追溯源码发现 boundedElastic-1线程阻塞在getSingleton方法synchronized (this.singletonObjects)锁上

那这时候主线程是否启动应用完成了呢？答案是没有，主线程也在实例化单例bean路上。追溯源码。主线程也在getSingleton方法synchronized (this.singletonObjects)锁上获取bean，boundedElastic-1线程正是主线程发起的，主线程在这里等待返回。boundedElastic-1线程在等待synchronized (this.singletonObjects)锁释放，主线程在getSingleton方法等待boundedElastic-1线程返回结果，由此死锁产生了。应用启动阻塞卡住了。