PHP - client socket connections

Question

I am trying to create a set of websocket clients with the following code:

$server = stream_socket_server("tcp://127.0.0.1:8080");

for ($i = 1; $i <= 50; $i++) {
    var_dump($i);
    stream_socket_client("tcp://127.0.0.1:8080");
}

The first 35, or so, connections are created very fast. Then everything slows down and every step takes 1 second to execute.

Could you explain to me why this behaviour happens? Is it caused by a configuration parameter? Is it a common websocket behaviour?

Answer 1

Working hypothesis: pending connections slows down the port

<?php
$server = stream_socket_server("tcp://127.0.0.1:8080");
for ($i = 1; $i <= 50; $i++) {
    var_dump($i);
    stream_socket_client("tcp://127.0.0.1:8080");
    stream_socket_accept($server);
}

Supplement:

In case listening party is server.c (modified not to accepting connections). Connections slow down after 27% of specified backlog. http://www.linuxhowtos.org/data/6/server.c

<?php
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($socket, "127.0.0.1", 8081);
$backlog = 500; // less than /proc/sys/net/core/somaxconn
socket_listen($socket, $backlog); 

for ($i = 1; $i <= 500; $i++) {
    var_dump($i);
    stream_socket_client("tcp://127.0.0.1:8081");
}