How to adjust the receiving buffer size of a socket through socket_set_option

In high concurrent network applications, the optimization of Socket communication performance is one of the important issues that developers must face. Especially in the data reception stage, the size of the buffer often directly affects the efficiency and stability of data processing. PHP provides socket_set_option function, which can be used to set multiple options of Socket, including the size of the receiving buffer ( SO_RCVBUF ). This article will explain in detail how to adjust the receive buffer size through this function to improve performance.

1. What is a receive buffer?

The receiving buffer of the Socket is a memory area allocated by the operating system to each Socket, which is used to temporarily store the received data. When the client sends data to the server, the data first enters the receiving buffer on the server side, and then is read and processed by the application.

If the buffer is too small, it may cause packet loss and lead to unstable communication; if the buffer is suitable or large enough, it can effectively reduce the number of reads and increase throughput.

2. Introduction to socket_set_option function

socket_set_option is an underlying function provided by PHP to set or obtain the behavioral options of Socket. The function prototype is as follows:

 bool socket_set_option(
    Socket $socket,
    int $level,
    int $option,
    mixed $value
)

• $socket : Socket instance.

• $level : Specifies the protocol layer of the option, and the receiving buffer uses SOL_SOCKET .

• $option : Set specific options, such as SO_RCVBUF .

• $value : The buffer size (bytes) to be set.

3. Example of setting the receiving buffer size

Here is a sample code to set the receive buffer to 1MB:

 <?php
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
    die("Socket Creation failed: " . socket_strerror(socket_last_error()));
}

// Set the receiving buffer size to1MB
$bufferSize = 1024 * 1024;
if (!socket_set_option($socket, SOL_SOCKET, SO_RCVBUF, $bufferSize)) {
    die("Failed to set the receive buffer: " . socket_strerror(socket_last_error($socket)));
}

// Binding and listening
socket_bind($socket, '0.0.0.0', 8080);
socket_listen($socket);

echo "Socket Started successfully，The receive buffer size is set to {$bufferSize} byte。\n";

// Subsequent processing is omitted
?>

Note that the actual buffer size may be limited by system kernel parameters. You can use socket_get_option() to view the actual effective size after setting:

 $actualSize = socket_get_option($socket, SOL_SOCKET, SO_RCVBUF);
echo "Actual buffer size: {$actualSize} byte\n";

4. Performance optimization suggestions

1. Set according to business needs : different application scenarios have different requirements for buffers. File transfers or video streams may require larger buffers, while real-time communications may be more latency-sensitive.

2. Use in combination with non-blocking mode : Large buffers help reduce read frequency, but combined with non-blocking reads can further improve processing efficiency.

3. Monitoring and Adjustment : Dynamically adjusting parameters is the key to high-performance services by monitoring the usage of the system's network buffer.

5. Summary

Adjusting the receiving buffer size through the socket_set_option() function is a simple and effective performance optimization method. In high-load applications, rationally configuring the receiving buffer can significantly improve the stability and processing efficiency of network communication. If you want to further deepen network optimization, you can also use options such as SO_SNDBUF , TCP_NODELAY , etc.

For more performance tuning tips for PHP Socket, please refer to https://gitbox.net/php-socket-performance-tuning .