The pain of a big concurrent server 1: Transmission response Mode

If you buy clothes on Taobao, you will find that a picture of the model is a bit slow to load. Sometimes the experience is just awful.

Let's analyze the transmission lifeline:

This is the ald.taobao.com domain name under the three requests, we found is in order to request the response, can not help but ask, why three requests not at the same time, could overlap it.

Now on the market all kinds of servers such as Nginx, Apache transmission of HTTP response is currently only one, namely: request----response----Request-----Response, we tentatively for the traditional mode, in the traditional mode, each request must be in the last response before, In fact, the overall response time is elongated, which is particularly noticeable on a number of content pages.

Today's internet has always been such a serial processing request, but the speed increased the disguise of narrowing the problem, slowing the development of parallel processing.

Some TCP-based streaming media Transmission control requests, is very much in need of parallel processing, but unfortunately the current market of video servers are blocking, but this kind of products are not many, we are holding can use on a good mentality, did not go to serious research to improve efficiency.

The traditional server handles the event in a way that multiple connections correspond to one process, for example, Nginx, a connection unique to a process, the event and memory is bound on the connection, the advantage is that the management of the event and memory can be done very simple, the disadvantage is also obvious, such as do not get the request--request-response---response.

This new pattern actually requires a connection that corresponds to multiple processes, and each process transmits content with a unique identification Fu Pe character.

Sharing connections between multiple processes is actually cumbersome, but it can be replaced with threads. The resulting event model is converted to the following pattern:

Memory and event management cannot be easily bound on a connection, unless the lock (inefficient, personal exclusion), should be in the speed and space compromise, such as the thread can allocate memory internally, the thread to deal with the event when the release, do not do is the processing granularity of the threads expanded, in some need of water processing business, You need to mount the memory allocated in the thread to the connection, or allocate large chunks of memory to the thread in advance.

The client can assign a unique ID for each emphasis, and the server's response also contains the corresponding ID, which avoids clutter in the client's response.

See more highlights of this column: http://www.bianceng.cn/Servers/zs/