polly poll

Let's first introduce nginx:Supports high-concurrency connections. the official test shows 5 W concurrent connections, but 2-4 W concurrent connections can be made in actual production, thanks to nginx's use of the latest epoll (Linux 2.6 kernel) and kqueue (FreeBSD) network I/O models. apache uses the traditional select model. Its stable prefork mode is a multi-process model, which requires frequent distribution of child processes, and consumes more CPU and other server resources than nginx.

Select and poll FunctionsIn the previous chapter, we encountered a problem that the client was blocked from reading data from the standard input. At the same time, the server required to close the connection for some reason and sent a fin to the client, the client can only know that the connection is closed after reading the data from the standard input. I/O reuse introduced in this chapter can solve this problem well. 1. i/O model. in UNIX, there are

PHP Instance-AJAX Polls AJAX PollsIn the following example, we will demonstrate a voting program through which the poll results are displayed without refreshing the page.Do you like PHP and AJAX? Example explanation-HTML pageWhen the user selects an option above, a function named "Getvote ()" is executed. This function is triggered by an "onclick" event.The poll.html file code is as follows:HTML>Head>MetaCharSet= "Utf-8">title>Beginner's T

First, the concept1. Poll Scenario DescriptionTake the key driver as an example to open the key driver file/dev/buttons in a blocking way, the application uses the Read () function to read the key value of the key. The effect of this is: if a keystroke is pressed, the process that invokes the read () function reads the data successfully, the application continues to execute, and if no keystrokes are pressed, it is always dormant, waiting for the butto

The example in this article describes how Python implements asynchronous Io via poll. Share to everyone for your reference. The specific analysis is as follows: Returns a polling object after using poll (), which supports the following methods: Pollobj.register (Fd,[,eventmask]) The first argument is to register a new file descriptor fd,fd either an integer file descriptor or an object with a Fileno () me

Reprint: http://bookjovi.iteye.com/blog/1186736 Asynchronous IO waiting in Linux is nothing more than three system calls: Select, Poll and Epoll. Many people do not understand the difference between three calls, or the lack of understanding, today on the combination of Linux kernel code detailed description of the three differences. Select The limit to select is the maximum of 1024 fd, you can view the posix_types.h in kernel, which defines the Fds

Transfer from http://www.cnblogs.com/zhuwbox/p/4222382.htmlPoll is similar to select, which iterates through the descriptor to see if a descriptor is ready. Returns the number of ready file descriptors if one is available. The poll function is as follows:#include int poll (struct POLLFD *fdarray, unsigned long nfds, int timeout)The first argument points to the pointer to the first element of the structure a

When doing network service, it is necessary to write concurrent service-side programs. The stability of the front-end client application is partly dependent on the client itself, and more depends on whether the server is fast enough and stable enough.The common Linux concurrent Server model; Multi-Process Concurrent server Multi-threaded Concurrent server Select multi-channel I/O transfer server Poll Multi-channel I/O forwarding server Epo

The reason why select is less efficient than Epoll : Select is polling,Epoll is trigger, so it is efficient. Select : 1.socket quantity limit :socketfd_ Setsize decided , kernel default 32*32=1024. 2. Operating Restrictions : by traversing the fd_setsize (1024x768 ) socket to complete the dispatch , regardless of which Socket is active , Go through it all over again . Poll :The number of 1.Socket is almost unlimited : The FD lis

Linux network communication has launched the Select, poll, Epoll three modes. Select has the following three questions:(1) Each time a select is called, the FD collection needs to be copied from the user state to the kernel state, which is very expensive when FD is very large.(2) At the same time, each call to select requires the kernel to traverse all of the FD that is passed in, which is also very expensive when FD is very large.(3) The number of f

The Libcurl also encapsulates both the I/O mechanisms of select and poll. The code uses a macro have_poll_fine to separate the two. If this macro is defined, use poll, otherwise select is used.The use code for both is defined in the function Curl_poll (), and the function is defined in the file lib/select.c. To facilitate analysis, reading will separate select and poll