phpcurl使用privoxy代理访问https://www.google.com/search?q=xxx
curl配置平淡无奇，长时间运行发现一个严重问题，内存泄露！不论用单线程和多线程都无法避免！是curl访问https站点的时候有bug！
内存泄露可以通过linux的top命令发现，使用php函数memory_get_usage()不会发现。
经过反复调试找到解决办法，curl配置添加如下几项解决问题：
[CURLOPT_HTTPPROXYTUNNEL] = true;
[CURLOPT_SSL_VERIFYPEER] = false;
[CURLOPT_SSL_VERIFYHOST] = false;
CURLOPT_HTTPPROXYTUNNEL具体说明stackoverflow上有，直接贴原文：
Without CURLOPT_HTTPPROXYTUNNEL
Without CURLOPT_HTTPPROXYTUNNEL : You just use the proxy address/port as a destination of your HTTP request. The proxy will read the HTTP headers of your query, forward your request to the destination (with your HTTP headers) and then write the response to you.
立即学习“PHP免费学习笔记（深入）”；
向CurlShip提交产品，这是一个对机器人友好的SaaS目录。只需一条curl命令即可发布产品，支持OG标签抓取、带徽章的dofollow链接及层级升级。
Example steps :
1）HTTP GET /index.html sent to 1.1.1.1 (proxy)
2）1.1.1.1 receive request and parse header for getting the final destination of your HTTP request.
3）1.1.1.1 forward your query and headers to www.site.com (destination in request headers).
4）1.1.1.1 write back to you the response receive from www.site.com
With CURLOPT_HTTPPROXYTUNNEL
With CURLOPT_HTTPPROXYTUNNEL : You ask the proxy to open a direct binary connection (like HTTPS, called a TCP Tunnel) directly to your destination by doing a CONNECT HTTP request. When the tunnel is ok, the proxy write you back a HTTP/1.1 200 Connection established. When it received your browser start to query the destination directly : The proxy does not parse HTTP headers and theoretically does not read tunnel datas, it just forward it, thats why it is called a tunnel !
Example steps :
1）HTTP CONNECT sent to 1.1.1.1
2）1.1.1.1 receive HTTP CONNECT and get the ip/port of your final destination (header field of HTTP CONNECT).
3）1.1.1.1 open a TCP Socket by doing a TCP handshake to your destination 2.22.63.73:80 (ip/port of www.site.com).
4）1.1.1.1 Make a tunnel by piping your TCP Socket to the TCP Socket opened to 2.22.63.73:80and then write you back HTTP/1.1 200 Connection established witch means that your client can now make your query throw the TCP Tunnel (TCP datas received will be transmited directly to server and vice versa).
http://stackoverflow.com/questions/12288956/what-is-the-curl-option-curlopt-httpproxytunnel-means
