[webkit-qt] 答复: about concurrent http connection restriction

[陈敏华]

Hello Jocelyn,

This really helps me to understand the connection handling in Qtwebkit,
thanks a lot.

All the best!

> -----邮件原件-----
> 发件人: Jocelyn Turcotte [mailto:jocelyn.turcotte at nokia.com]
> 发送时间: 2011年11月29日 20:26
> 收件人: ext 陈敏华
> 抄送: webkit-qt at lists.webkit.org
> 主题: Re: [webkit-qt] about concurrent http connection restriction
> 
> Hello,
> comments below.
> 
> On Tue, 29 Nov 2011 14:21:27 +0800
> ext 陈敏华 <chenmh at cn.fujitsu.com> wrote:
> 
> > Hello everyone，
> >
> > I just want to figure out how Qtwebkit handle for concurrent http
connections,
> and I have found some relevant code from file "ResourceRequestQt.cpp. The
code
> is as follows, but I can't understand it well.
> >
> > // Currently Qt allows three connections per host on symbian and six
> > // for everyone else. The limit can be found in
qhttpnetworkconnection.cpp.
> > // To achieve the best result we want WebKit to schedule the jobs so we
> > // are using the limit as found in Qt. To allow Qt to fill its queue
> > // and prepare jobs we will schedule two more downloads.
> > // Per TCP connection there is 1 current processed, 3 possibly pipelined
> > // and 2 ready to re-fill the pipeline.
> > unsigned initializeMaximumHTTPConnectionCountPerHost()
> > {
> > #ifdef Q_OS_SYMBIAN
> >     return 3 * (1 + 3 + 2);
> > #else
> >     return 6 * (1 + 3 + 2);
> > #endif
> > }
> >
> > My question is as follows:
> > 1. Does the maximum number of concurrent http connection for each host
equal
> to 36？
> The name of this WebCore methods can be misleading, the roles of each is
that
> WebCore sends requests to Qt, and Qt establish connections to send those
> requests. So in this case, there would be maximum 36 requests distributed
on
> 6 parallel connections to each host. If more requests are pending, WebCore
will
> keep them for itself instead of throwing all of them at Qt.
> 
> > 2. Is there any restriction for overall number of http connection that
can
> be hold by Qtwebkit at any time？
> I didn't verify but I think we don't, though the OS might have some limits
of
> its own.
> 
> > 3. Http 1.1 has a concept called "persistent connection", does QtWebkit
> support this feature？ If so， what's the relationship between the number
of
> http request& reponse that have been made and the number of tcp sockets
> established?
> The 6 parallel connections per host held by QNetworkAccessManager are
> persistent connections, when a pending request is fed to Qt, any already
opened
> connection will be used if available instead of establishing a new one.
> 
> > Does anybody can help me solve this problem?
> > Thank you very much.
> Hope this helps.
> 
> Jocelyn