httpClient多线程问题

问题： 今天线上出现一个httpclient的问题：

java.lang.IllegalStateException: Connection is not open
at org.apache.commons.httpclient.HttpConnection.assertOpen(HttpConnection.java:1
276)

at org.apache.commons.httpclient.HttpConnection.getResponseInputStream(H
ttpConnection.java:857)
at org.apache.commons.httpclient.HttpMethodBase.readResponseHeaders(Http
MethodBase.java:1790)
at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodB
ase.java:1592)
at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.j
ava:995)
at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(Htt
pMethodDirector.java:397)
at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMe
thodDirector.java:170)
at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.jav
a:396)
at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.jav
a:324)
at com.kingpoint.BiDownTestCookie.getByPostMethod(BiDownTestCookie.java:
172)
at com.kingpoint.ClickIE.run(ClickIE.java:27)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462) 场景：我通过多线程调用外部http服务，但是我的httpClient是一个单例，当某个请求返回以后，还有的请求用的是同样的单例，而上一个请求的连接我已经关闭了，所以导致connection is not open。
解决方案：

1. 请求加锁

2. 每次new HttpClient(); 保证独立。

参考：http://www.iteye.com/problems/63688