在使用springcloud config自动刷新功能难免会踩到一些坑，下面来介绍下
在生成中经常需要动态刷新配置，只需要增加@RefreshScope，并且执行手动刷新链接/actuator/refresh,或者集成springcloudbus来自动刷新，但是有些配置动态刷新时需要实例化一些spring内部复杂的对象，这里就不能自动更新了，比如说zuul。
zuul路由配置可以自动刷新，
zuul:
sensitive-headers:
routes:
api-b:
path: /apib/**
serviceId: dataeyeServer
但是设计到zuul内部resttemplate的一些超时配置，如果改动了，并且手动刷新，则会出现标题中的错误Connection pool shut down on “zuul.host.*” property change
zuul:
host:
connect-timeout-millis: 10000
socket-timeout-millis: 600000
错误信息如下：
java.lang.IllegalStateException: Connection pool shut down
at org.apache.http.util.Asserts.check(Asserts.java:34) ~[httpcore-4.4.8.jar:4.4.8]
at org.apache.http.pool.AbstractConnPool.lease(AbstractConnPool.java:191) ~[httpcore-4.4.8.jar:4.4.8]
at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.requestConnection(PoolingHttpClientConnectionManager.java:257) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:176) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[httpclient-4.5.3.jar:4.5.3]
at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.3.jar:4.5.3]
at org.springframework.http.client.HttpComponentsClientHttpRequest.executeInternal(HttpComponentsClientHttpRequest.java:89) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:659) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:628) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:302) ~[spring-web-4.3.13.RELEASE.jar:4.3.13.RELEASE]
这是由于自动刷新时，由于host中超时时间配置变更导致连接池先关闭，再准备重新创建，但是在重现创建的过程中却没有重新创建连接池，还是引用原有连接池导致报错。
解决方案一：将springcloud升级到Edgware.RELEASE，即
spring-cloud-commons-dependencies 版本升级到1.3.2.RELEASE
解决方案二：手动实例化连接池
参考资料
https://github.com/spring-cloud/spring-cloud-netflix/issues/3406
https://github.com/spring-cloud/spring-cloud-commons/issues/330
https://github.com/spring-cloud/spring-cloud-config/issues/918
