springcloud config坑系列一之Connection pool shut down on "zuul.host.*" property change

在使用springcloud config自动刷新功能不免会踩到一些坑，下面来介绍下 在生成中常常须要动态刷新配置，只须要增长@RefreshScope，而且执行手动刷新连接/actuator/refresh,或者集成springcloudbus来自动刷新，可是有些配置动态刷新时须要实例化一些spring内部复杂的对象，这里就不能自动更新了，好比说zuul。 zuul路由配置能够自动刷新，

zuul:
  sensitive-headers:
  routes:
    api-b:
      path: /apib/**
      serviceId: dataeyeServer

可是设计到zuul内部resttemplate的一些超时配置，若是改动了，而且手动刷新，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

错误信息以下：

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]

这是因为自动刷新时，因为host中超时时间配置变动致使链接池先关闭，再准备从新建立，可是在重现建立的过程当中却没有从新建立链接池，仍是引用原有链接池致使报错。 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：手动实例化链接池

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