socket_listen

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

socket_listen — Listens for a connection on a socket

说明

socket_listen ( Socket $socket , int $backlog = 0 ) : bool

After the socket socket has been created using socket_create() and bound to a name with socket_bind(), it may be told to listen for incoming connections on socket.

socket_listen() is applicable only to sockets of type SOCK_STREAM or SOCK_SEQPACKET.

参数

socket: A Socket instance created with socket_create() or socket_addrinfo_bind()
backlog: A maximum of backlog incoming connections will be queued for processing. If a connection request arrives with the queue full the client may receive an error with an indication of ECONNREFUSED, or, if the underlying protocol supports retransmission, the request may be ignored so that retries may succeed.

Note:
The maximum number passed to the backlog parameter highly depends on the underlying platform. On Linux, it is silently truncated to SOMAXCONN. On win32, if passed SOMAXCONN, the underlying service provider responsible for the socket will set the backlog to a maximum reasonable value. There is no standard provision to find out the actual backlog value on this platform.

返回值

成功时返回 true，或者在失败时返回 false。 The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error.

更新日志

版本	说明
8.0.0	`socket` is a Socket instance now; previously, it was a resource.

参见

socket_accept() - Accepts a connection on a socket
socket_bind() - 给套接字绑定名字
socket_connect() - 开启一个套接字连接
socket_create() - 创建一个套接字（通讯节点）
socket_strerror() - Return a string describing a socket error
socket_addrinfo_bind() - Create and bind to a socket from a given addrinfo

User Contributed Notes

renmengyang567 at gmail dot com 07-Apr-2019 05:52


<?php

// create for tcp

$sock = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));

socket_bind($sock, '127.0.0.1',5000);

socket_listen($sock,1);

sleep(20);

?>



<fruit>

netstat  -ntpl

Active Internet connections (only servers)

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name

tcp        0      0 127.0.0.1:5000          0.0.0.0:*               LISTEN      1839/php

Karuna Govind (karuna.kgx gmail) 15-Jul-2008 04:10


To change the maximum allowed backlog by your system (*nix machines only), first you need to find the variable for this limit:



sudo sysctl -a | grep somaxconn



On ubuntu boxes, it returns net.core.somaxconn (you need to look for the 'somaxconn' variable, the full name will vary across different systems).



Update this to a large number as follows:



sudo sysctl -w net.core.somaxconn=1024



This will work straight away. no restart required.