Memcached is a generic, open-source, and distributed memory object caching system. It is intended to reduce database load while increasing the speed of dynamic web applications. It enables us to make better use of our system memory. In 2003, Brad Fitzpatrick of Danga Interactive created Memcached for LiveJournal. It was written in Perl but then rewritten in C by Anatoly Vorobey.
Memcached allows you to move memory from a system component that requires less memory to one that requires more memory. This article will explain what memcached is, how to install it, and how it might be useful in the software industry.
What is Memcached?
Memcached can be written mem-cash-dee or mem-cached. It is a high-performance, distributed memory object caching technology that is free and open-source. Memcached is used to improve the performance of dynamic web applications by minimizing database demand. Memcached is used by various websites which have large amounts of data, such as YouTube, Wikipedia, and Twitter.
Since Memcached can be easily installed on any Windows or Unix machine, it is frequently used in memory caching software. All of the major programming languages, including PHP, Java, C/C++, Python, Ruby, Perl, and others, allow API integration. Based on key values, it retains data for brief, arbitrary words or objects, including page rendering, API requests, and database query results.
Components of Memcached
Memcached is composed of four major components. These components enable the client and server to collaborate in order to transmit cached data as efficiently as possible:
Client Software: It connects to Memcached servers, sends data to be cached, and retrieves data from the cache. The client application connects to a collection of Memcached servers and distributes data among them through hashing.
Client-based Hashing System: The client-based hashing algorithm is used to identify which Memcached server in the pool will be in charge of storing or retrieving a specific key-value pair.
Server Software: The key-value pairs are actually kept in an internal hash table by the server software. The server keeps data in memory when a client transmits it to be cached. When a client submits a key to request data, the server searches the hash table and, if the requested value exists, returns it.
LRU (Least Recently Used): Memcached uses the LRU cache deletion policy. When to remove outdated or infrequently accessed data from the cache in order to make place for fresh data is decided by this.
Features of Memcached
Some of the features of Memcached are given below:
It is open-source and very scalable
Memcached operates as a stand-alone program. As a result, even if you stop using your application, the cached data will continue to exist in memory while the service is active
The Memcached server is a large hash table that reduces the burden on the databases
For websites that have heavy database loads, it is particularly effective
Disadvantages of Memcached
Some of the disadvantages of Memcached are given below:
It is not a fault-tolerant tool
It is extremely slow when compared to in-memory caching, primarily due to serialization or deserialization and network latency
It does not serve as a persistent data store
If your device's storage becomes too full, that can decrease your computer's speed
Working of Memcached
Memcached is made up of four primary components that allow it to store and retrieve data. Each item contains a key, an expiration time, and raw data. At a high-level Memcached works as follows:
When a client requests data, Memcached checks to see if it is already in the cache.
There could be two results. If the data is stored in the cache, return it from Memcached (no need to query the database). If the data is not stored in the cache, then it is queried from the database, retrieved, and then stored in Memcached.
When information is changed or an item's expiry value expires, Memcached updates its cache to ensure that fresh content is supplied to the client.
This configuration has several Memcached servers and several clients. A hashing algorithm is used by clients to determine which Memcached storage server to use. This helps in load distribution.
The server then computes a second hash of the key to determine where the associated value should be stored in an internal hash table. The following are some essential elements of Memcached architecture:
Only one server receives data
Servers do not share information
Servers store the values in RAM; when RAM becomes full, the oldest value is destroyed
Installation of Memcached
Step 1: Download the Memcached zip setup using the URL provided below based on your system specifications.
The URL above will automatically download the Memcached zip configuration and place it in the "Downloads" directory.
Step 2: Right-click on the Memcached zip setup file in the "Downloads" directory. Then, from the options provided, select "Extract All".
Step 3: Select the location where the retrieved Memcached configuration will be saved.
Step 4: When you open the extracted folder, you'll discover the Memcached execution file.
Step 5: Copy the location of the "memcached.exe" file from the "Address" bar.
Step 6: In the "Startup" menu, type "cmd" and open the Command Prompt from the search result.
Step 7: To open the directory where you discovered the "memcached.exe" file, use the "cd" command.
cd C:\Users\HP\Downloads\memcached-win64-1.4.4-14\memcached
Then, use the following command to install Memcached on the system:
memcached.exe -d install
The successful execution of the command indicates that Memcached has been successfully installed on the system.
Step 8: Then, launch Memcached services by executing the following command.
memcached.exe -d start
Step 9: To test the Memcached installation and determine whether or not the Memcached service is active, launch the Task Manager application by finding "Task Manager" in the "Startup" menu. From the “Services” menu, you can see that Memcached is successfully installed and running on the system.
Frequently Asked Questions
What is Dogpile Effect?
The dogpile effect occurs when a cache expires, and many requests from the client are made at the same time. This impact can be avoided by using a semaphore lock. When a value expires in this system, the first process gains the lock and begins creating new value.
What conditions prevent the cache from retaining the stored information?
The following situations prevent the cache from preserving the stored information: when the memory allotted to the cache is exhausted, or when a cached item is erased, or when a specific item in the cache expires.
What is ElastiCache?
Amazon ElastiCache is an Amazon Web Services (AWS) cache-as-a-service. It is a completely managed solution for establishing, administering, and growing a cloud-based distributed in-memory cache system.
In AWS, how to enable ElastiCache?
Navigate to ElastiCache in the AWS Management Console on your browser. In the center of the page, click the blue "Create" button. We can select the Redis engine and enable Cluster Mode for this cluster. Give your cluster a name and a description next.
Conclusion
Memcached has established itself as a dependable and effective distributed caching technology, considerably enhancing web application performance by lowering database load and response times. Since data may be instantly fetched from the cache rather than having to wait for possibly slower database searches, this results in a smoother and more fluid user experience.
306+ registered