apache的http代理出现 502 Proxy Error

前不久刚部署好的网站，忽然访问报错提示错误

引用

Http 502 Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /.
Reason: Error reading from remote server

看了半天也没看出个所以然来， 刚刚还好好的呢！过了一会网站又能打开了....
查看了一下apache的access_log。发现

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.....Get / HTTP/1.0....

这是ie5.5以下的版本访问过。所以又找来台ie5.5(挺难整，这年头这玩意少了！！)访问了一下，然后出错。在用别的机器访问错误还有。在刷新了一会又好了!
就这个问题Google了一下发现是mod_proxy的事，又G了一下他的文档
http://httpd.apache.org/docs/2.3/mod/mod_proxy.html
找到了这一段话

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For circumstances where mod_proxy is sending requests to an origin server that doesn't properly implement keepalives or HTTP/1.1, there are two environment variables that can force the request to use HTTP/1.0 with no keepalive. These are set via the SetEnv directive.
These are the force-proxy-request-1.0 and proxy-nokeepalive notes.

译了一下大概是这意思(不是我译的)

引用

当mod_proxy向一个没有正确实现持久连接(KeepAlive)或HTTP/1.1的原始服务器发送请求的时候，可以通过设置两个环境变量来发送不带持久连接(KeepAlive)的HTTP/1.0请求。这两个变量是通过SetEnv指令设置的。
以下是force-proxy-request-1.0和proxy-nokeepalive的例子：

ProxyPasshttp://buggyappserver:7001/foo/
SetEnvforce-proxy-request-1.01
SetEnvproxy-nokeepalive1

最后在我的httpd.conf的VirtualHost里加上了上面的两行设置

80>
JkMount/hr/servlet/*worker1
JkMount/hr/*.jspworker1
JkMount/hr/*.doworker1
ServerAdminnjgnini@163.com
ServerNamewww.iteye.com
ServerAliaswww.iteye.com.cn
RewriteEngineOn
RewriteRule^/$　/hr/　[R,P]

SetEnvforce-proxy-request-1.0.1
SetEnvproxy-nokeepalive1

重启apache，在拿ie5.5访问O了