principle
When reading data from the stream inside, this data could not down the stream, in order to avoid idle CPU, introduced agents: select, pool, and later introduced changes epool to monitor the occurrence of file handles, this agency more powerful, it can be observed simultaneously many stream I / O events, in his spare time, will the current thread blocked out, when one or more streams have I / O event, woke up from the blocking states, so our program will poll over all streams. IO using select only know of the incident, and a few really do not know what happened, the introduction of epool, it can tell us which flow (flow: is a file, sockets, pipe and other kernel objects can be IO operations) What happens in the IO event.
epool usage
import select import select module
epoll = select.epoll () objects to create a epoll
file handle and events epoll.register (file handle, event type) registered to monitor
the type of event:
select.EPOLLIN readable event
select.EPOLLOUT can write event
select .EPOLLERR error event
select.EPOLLHUP client disconnection events
epoll.unregister (file handle) destroyed the file handle
epoll.poll (timeout) when a file handle changes will be in the form of a list of active reporting to the user process, timeout
to timeout , defaults to -1, i.e., waits until the file handle changed, if designated as a
so epoll report every 1 second change of the current file handle return null if no change
epoll.fileno () returns the control file is described epoll character (the Return the epoll the Control File descriptor)
epoll.modfiy (fineno, event) fineno file descriptors for the event type event descriptor is to modify the action event corresponding
one from the specified file descriptor epoll.fromfd (fileno) Creating an epoll objects
epoll.close () closed epoll file descriptor object control
Examples
# ! / Usr / bin / env Python # - * - Coding: UTF-8 - * - Import socket Import the SELECT Import Queue # Create a socket object serversocket = socket.socket (socket.AF_INET, socket.SOCK_STREAM) # Set the IP address multiplexing with serversocket.setsockopt (socket.SOL_SOCKET, socket.SO_REUSEADDR, 1 ) # ip address and port number server_address = ( " 127.0.0.1 " , 8888 ) # bind IP address ServerSocket.bind (server_address) # monitor, and set the maximum connection number serversocket.listen (10 ) Print " server started successfully, monitor IP:" , Server_address # server set non-blocking serversocket.setblocking (False) # timeout timeout = 10 # create epoll event object, the follow-up to monitor the event to which the epoll = select.epoll () # registration server listens to fd waiting to be read event set epoll.register (serversocket.fileno (), select.EPOLLIN) # save dictionary connection client message format} { message_queues = {} # file handle object corresponding to the dictionary, the format {handles: object} = fd_to_socket {serversocket.fileno (): ServerSocket,} the while True: Print " wait active connection ...... " # polling register set of events, the return value [(a file handle corresponding to the event), (. ..), ....] Events = epoll.poll (timeout) IF not Events: Print " epoll timeout no active connection, re-polling ...... " the Continue Print " there " , len (Events), " a new event, starts processing ...... " for fd, event in Events: socket = fd_to_socket [fd] # if the current activity socket server socket, indicate a new connection IF socket == serversocket: connection, address = ServerSocket.accept () Print " new connection: " , address # new connection socket is set to a non-blocking connection.setblocking (False) # Register a new connection to be read fd set of events epoll.register (connection.fileno (), select.EPOLLIN) # save file handles, and the object of the new connection to the dictionary fd_to_socket [connection.fileno ()] = connection # to key target for the new connection, the value stored in the queue, stored information for each connection message_queues [connection] = Queue.Queue () # close event elif event & select.EPOLLHUP: Print ' Client Close ' # Log off the client in the epoll file handle epoll.unregister (fd) # close the file handle client fd_to_socket [fd] .close () # Deleting closed client-related information in a dictionary del fd_to_socket [FD] # readable event elif Event & select.EPOLLIN: # receiving data Data = socket.recv (1024 ) IF Data: Print " receive data: " , data, " client: " , socket.getpeername () # the client data into the corresponding dictionary message_queues [Socket] .put (data) # modify message read event set is connected to the write wait (i.e., the corresponding client after receiving the message, and then modify it and add fd write event collection) epoll.modify (fd, select.EPOLLOUT) # can write event elif event &select.EPOLLOUT: the try : # obtain the corresponding client information from the dictionary msg = message_queues [socket] .get_nowait () the except Queue.Empty: Print socket.getpeername (), " Queue empty " # modified file handle to read events epoll. the Modify (fd, select.EPOLLIN) the else : Print " to send data: " , the data, " client: " , socket.getpeername () # sending data socket.send (msg) # cancellation of the server file handle in the epoll epoll.unregister (serversocket.fileno ()) # close the epoll epoll.close () # close server Socket serversocket.close () server code
# ! / Usr / bin / env Python # - * - Coding: UTF-8 - * - Import socket # Create the client socket object ClientSocket = socket.socket (socket.AF_INET, socket.SOCK_STREAM) # server IP address and port number tuple the server_address = ( ' 127.0.0.1 ' , 8888 ) # client connections specified IP address and port number clientsocket.connect (the server_address) the while True: # of input data data = the raw_input ( ' Please iNPUT: ' ) # client transmission data clientsocket.sendall (data) # client receives the data = clientsocket.recv SERVER_DATA (1024 ) Print ' data received by the client: ' SERVER_DATA # closed client Socket clientsocket.close () client code
This article reference links: https://www.cnblogs.com/maociping/p/5132583.html