主流浏览器并发连接数

浏览器默认最大并发连接数

浏览器默认对同一域下的资源，只保持一定的连接数，会阻塞过多的连接。rfc2616建议不超过2个:

Clients that use persistent connections SHOULD limit the number of simultaneous connections that they maintain to a given server. A single-user client SHOULD NOT maintain more than 2 connections with any server or proxy. A proxy SHOULD use up to 2*N connections to another server or proxy, where N is the number of simultaneously active users. These guidelines are intended to improve HTTP response times and avoid congestion.

不同浏览器的默认值不一样，对于不同的HTTP协议其值也不一样。见下表。
 

上表数据来自Steve Souders。

总的来看，HTTP1.0下允许的连接数普遍大于HTTP1.1协议下的，是因为HTTP1.1是保持连接的，本身对同域下资源的获取就是优化的，且对资源的消耗要大于HTTP1.0。在rfc2616中说到，限制连接数的目的在于提高响应速度和避免拥塞。

修改浏览器最大连接数

1. Firefox

在文件 X:\Program Files\Mozilla Firefox\greprefs\all.js中，有如下的参数：

// if network.http.keep-alive is true, and if NOT connecting via a proxy, then
// a new connection will only be attempted if the number of active persistent
// connections to the server is less then max-persistent-connections-per-server.
pref("network.http.m camerabagss.us a x-persistent-connections-per-server", 6);

// if network.http.keep- camerabagss.us a live is true,  camerabagss.us a nd if connecting vi camerabagss.us a   camerabagss.us a  proxy, then  camerabagss.us a 
// new connection will only be  camerabagss.us a ttempted if the number of  camerabagss.us a ctive persistent
// connections to the proxy is less then m camerabagss.us a x-persistent-connections-per-proxy.
pref("network.http.max-persistent-connections-per-proxy", 8);

2. IE

需要修改注册表或组策略，详情见微软的技术支持。

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