Memcache cluster configuration in PHP to improve web application performance

The performance of Web applications has always been the focus of developers. Among them, caching technology has always been one of the important means to improve the performance of Web applications. In caching technology, Memcache is a widely used caching system with the characteristics of high speed, scalability and reliability. In this article, we will introduce how to configure a Memcache cluster to improve the performance of web applications.

1. Overview of Memcache

Memcache is an open source, high-performance distributed memory object cache system written by Lloyd Hilaiel. It is mainly used in web applications to improve the access speed and response speed of web applications. Memcache works by storing data in memory where it can be read and written extremely quickly when accessed. For example, a PHP application can first query Memcache every time it obtains data from the database. If there is a result, it will be used directly. If not, it will be taken out from the database, and the result will be stored in Memcache. The next time it is obtained, it will be read directly from Memcache. This greatly improves the response speed of the application.

Memcache cluster is a cluster mode based on multiple servers. In its internal implementation, there is no relationship between each server. There is no master-slave distinction. That is, each server is equal and can be used. Accept read and write requests from clients. The client distributes each key-value pair on different Memcached Servers through a consistent hash algorithm or a sharding algorithm, thus avoiding single points of failure and improving reliability.

2. Memcache cluster configuration steps

1. Install Memcache service
sudo apt-get update
sudo apt-get install memcached

2.Install Memcache Extension
sudo apt-get install php-memcached

3. Add the Memcache extension in the php.ini file
extension=memcached.so

4. Write the Memcache client program
// Connect to Memcache service
$mem = new Memcached();
$mem->addServer("127.0.0.1", 11211);

// Set cache
$mem->set("key1", "val1", 0, 60);

// Get cache
$val = $mem->get ("key1");
echo "Value:".$val;

// Delete cache
$mem->delete("key1");

/ / Close the connection
$mem->quit();
?>

The above is a single-node Memcache cache example. Next, we will introduce how to form multiple nodes into a Memcache cluster. .

5. Configure Memcache cluster
Before configuring the Memcache cluster, you need to understand some related concepts:

(1) Node: Memcached Server instance, that is, each server.

(2) Hash function (Hash): The consistent hash algorithm can use PHP’s builtin crc32() function, and the sharding algorithm can use a custom hash function.

(3) Node keyword (Key): It can be composed of the host name, IP address and port number of the node as needed, and the key will be mapped to the corresponding node according to the hash algorithm.

(4) Weight: Node weight is used to balance the performance of each node in the cluster. If a node's weight is 0 or negative, the node will not be used.

The following is a simple cluster configuration example, including 5 nodes, including 4 normal nodes and one abnormal node:

$servers = array(
array('localhost ', 11211, 20),
array('localhost', 11212, 40),
array('localhost', 11213, 40),
array('localhost', 11214, 40),
array('localhost', 11215, 0),
);

In the above configuration, 5 nodes are enabled, with weights of 20, 40, 40, 40, and 0 respectively. The weight of the last node is 0, which means that the node has been saved, that is, all the weights are occupied by the node.

6. Use consistent hashing algorithm

Memcached uses consistent hashing algorithm (Consistent Hashing) to disperse each key-value pair on different Memcached Servers. The following is how to use consistency Example of hash algorithm:

// Connect to Memcache service
$mem = new Memcached();

// Add cluster nodes and use consistency Hash algorithm
$mem->addServers($servers);

// Set cache
$mem->set("key1", "val1", 0, 60);

// Get the cache
$val = $mem->get("key1");
echo "Value:".$val;

// Delete the cache
$mem->delete("key1");

//Close the connection
$mem->quit();
?>

Use addServers($servers) method to add one or more servers to the connection pool, where the server array consists of the node list $servers. Each array element in the node list is a node host name, port number, and node weight. array of values.

3. Summary

Memcache cluster is a high-performance caching system that can significantly improve the access speed and response speed of web applications. In actual applications, it is necessary to configure the appropriate cluster size and node weight for the system according to specific conditions to achieve optimal performance and reliability. Through the introduction of this article, we not only understand the advantages and working principles of Memcache, but also learn how to configure a Memcache cluster. In practice, we can apply it to our own web application projects faster and better.

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