What exactly is the 'Waiting for response' msg on Firebug's Net tab?

Question

As sou can see from the screenshot most of the time spent is waiting for a server response (thats the purple coloured area).

What exactly is that server response time? Is the server too slow? Is my connection too slow? Can't the server process much information at once (I've got many files there, I know I'll combine them to fewer)? What do I have to do to minimise that waiting time?

PS. all the data are on the same server but I'm using subdomains so that the browser can process more files at once.

Earthling

Answer 1

This article is quite nice about features of firebug : Introduction to Firebug: Net Panel (especially the timeline section)... But it doesn't say much about what "waiting for response" exactly means :-(

Still, the timeline is (quoting) :

• DNS Lookup - DNS resolution time
• Connection - elapsed time required to create a TCP connection
• Queuing - elapsed time spent in a browser queue waiting for a network connection
• Waiting For Response - waiting for a response from the server
• Receiving Data - elapsed time required to read entire response from the server (and/or time required to read from cache).
• DomContentLoaded event - time when DomContentLoad event was fired (since the beginning of the request, can be negative if the request has been started after the event)
• load event - time when page load event was fired (since the beginning of the request, can be negative if the request has been started after the event)

So, I'm guessing that the "waiting for response" period is the time during which the browser has sent the request to the server, and has not received any response yet : it is "waiting" for some content beginning to arrive :

• the browser is no longer waiting for the network connection : the request is sent
• and the browser is not yet reading response from the server.

In the case of a server generating the whole page before beginning sending it to the browser, I suppose the "waiting for response" time would be correspond to :

• time for the request to travel from the browser to the server
• plus time for the request to be processed by the server (ie, time to generate the whole page)
• plus time for the first byte of data traveling from the server to the browser.

Hope this helps :-)

Pentecostal

thanks for the response. Is there a way to check which one of those 3 (browser->server, process, server->browser) takes the longest? – Earthling

You're welcome :-) I don't think it is possible to know in which one of those 3 steps you are : the only thing the browser knows is that the request has been sent, and that no result has come back yet -- on the browser side, there is no way to know if the server has received the request, if it is processing it, ... I suppose you'll have to do some logging on the server-side, at least if you want to know how long it took to generate the page. – Pentecostal

If you can just ping the server, you'll get a good estimate of the transfer latency; Most of the rest (for small files) will be processing time. – Lonergan

I agree with this answer, I am writing a test document for a company website and I defined the 'Waiting' time as follows: Server – The time it takes after the browser has completed sending request, for the remote host to return packet data (in the same TCP stream). Note: This time will include latency between the request data and the returned data, though this will be well below 50 ms on an average corporate LAN and hence negligible. <-- in my case - ping your servers to check yourself. – Corron

Answer 2

Not sure which version of firebug you use. But in my version(1.6.0) there is also a "sending" time.

Check this post: http://www.softwareishard.com/blog/firebug/firebug-net-panel-timings/ It basically says "waiting" time is the time from the request is sent to server till first byte is received. To me, it sounds to me pretty much equal to the server side processing time.

Argenteuil