Memcached Archives - Web and Mobile App Development | Custom Application Development Company

With the increasing number of apps going live on the web, it’s becoming common to see that they use multiple servers. This is mainly due to scalability and availability purposes. But, these types of applications are also often not as responsive as they should be. Using a simple gem called DynamoDB and Memcached will allow you to achieve higher performance in your Rails app. Let me explain,

What is Memcached

Memcached is a high performance, free and open source distributed memory caching system used to speeding up dynamic web applications by alleviating database load. Memcached is simple yet powerful. Its simple design promotes quick deployment, ease of development, and solves many problems facing large data caches.

It is used for speeding up dynamic web applications by reducing database load. In other words, every time a database request is made it adds additional load to the server. Memcached reduces that load by storing data objects in dynamic memory (think of it as short-term memory for applications). Memcached stores data based on key-values for small arbitrary strings.

How does Memcached work?

Memcached is comprised of four main components

Client software – Which is given a list of available Memcached servers
A client-based hashing algorithm – Chooses a server based on the “key”
Server software – Stores values and their keys into an internal hash table
LRU – Determines when to throw out old data or reuse memory

Each item is comprised of a key, expiration time, and raw data.

At a high-level Memcached works as follows:

The client requests a piece of data which Memcached checks to see if it is stored in cache.
There are two possible outcomes here:
1. If the data is stored in cache: return the data from Memcached (no need to check the database).
2. If the data isn’t stored in cache: query the database, retrieve the data, and subsequently store it in Memcached.
Whenever information is changed or the expiry value of an item has expired, Memcached updates its cache to ensure fresh content is delivered to the client.

A few important points about Memcached architecture include:

Data is only sent to one server.
Servers don’t share data.
Servers keep values in RAM. If RAM runs out the oldest value is discarded.

What is DynamoDB

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability. With DynamoDB, you can create database tables that can store and retrieve any amount of data and serve any level of request traffic. You can scale up or scale down your tables’ throughput capacity without downtime or performance degradation.

DynamoDB is a particularly good fit for the following use cases

Applications with large amounts of data and strict latency requirements
Server less applications using AWS Lambda
Data sets with simple, known access patterns

Installing Memcached

There are a few ways you can install Memcached. Depending on which system you’re using, the method will vary. As outlined on the official Memcached Installation Wiki, installation from a package is simple.

Using Memcached with DynamoDB in Rails

Memcached is a quick in-memory protest reserving framework that can make Rails run much quicker with not very many changes. Memcached will work on any database used in Rails application.

When the table is small and request volume is low this isn’t much of an issue, but as your database and user volume grow, these can impact the performance of your application. In such cases Memcached plays an important role to reduce the database load by caching the request object in memory.

To use Memcached in Rails app, follow the below steps

Install dalli gem

[code language=”css”]gem ‘dalli'[/code]

Add “dalli” gem to your gem file and install it.

Development/Production file

[code language=”css”]config.cache_store = :dalli_store</em><em> </em><em>config.action_controller.perform_caching = true[/code]

Add the above lines in your development.rb or production.rb file as per the requirement

Add Memcached in your method

[code language=”css”]search_query = "user_id = :user_id AND is_approved = :is_approved"
search_param = {":user_id" => params[:user_id], ":is_approved" => ‘t’}
all_games = Rails.cache.fetch(‘all_lists’, expires_in: 2.minutes)
{
do_scan(Article.table_name,search_query,search_param)
}[/code]

The above query syntax is an example of combination of Memcached and DynamoDB. In this example once the query executed and the result will store in the “all_list” key of the Memcached and expire after 2 minutes automatically.

Conclusion:

DynamoDB and Memcached is a powerful combination for your Rails app. If you’re looking to improve the performance of your Rails application, this may be the solution for you.

DynamoDB and Memcached involves storing information in an external database, which can be retrieved with a single call. This will allow you to avoid the constant querying of data from your application’s memory.

There are many benefits to this gem, but most importantly, increased response time for your application. Faster response times mean less downtime and more satisfied customers.

You have rails application but don’t know how to maximize the performance with DynamoDB and Memcached. Andolasoft has experienced rails developer who has good hands on DynamoDB and Memcached. So fell free to discuss about your project. Book a free consultation

Introduction:

MemcacheD is easy yet powerful. It’s manageable design promotes fast deployment, ease of exaggeration, and solves many problems related to large data caches. It has its inbuilt APIs which provide a very large hash table distributed across multiple machines & uses internal memory management which is more efficient in the simplest use cases because it consumes comparatively less memory for metadata. MemcacheD supports only String data type which are ideal for storing read-only data.

Memcached is a volatile in-memory key-value origin. It is rude, multi-threaded and used primarily for caching objects.

Redis is an open source in-memory data structure store which also can be used as a database as well as caching. It supports almost all types of data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs and geospatial indexes through radius queries. Redis also can be used for messaging system used as pub/sub.

Internal Architecture:

Here are the key points to consider,

Installation:

Installing Redis is so much easier. No dependencies required.

Memory Usage:

MemcacheD’s internal memory supervision, while not exactly a substitute to Redis; Is more efficient because it consumes comparatively less memory resources for metadata. For easy key-value pairs, MemcacheD is more memory efficient than Redis. Redis is more memory efficient, only after you use Redis hashes.

Persistence:

If you are using MemcacheD, data might be lost with a restart and rebuilding cache is a costly process. On the other hand, Redis can handle persistent data. By default it syncs data to the disk at least every 2 seconds, offering optional & tuneable data persistence meant to bootstrap the cache after a planned shutdown or an unintentional failure. While we tend to regard the data in caches as volatile and transient, persisting data to disk can be quite valuable in caching scenarios.

Replication:

MemcacheD does not support replication, whereas Redis supports master-slave replication. It allows slave Redis servers to be the exact copies of master servers. Data from any Redis server can replicate to any number of slaves. Replication can be used for implementing a cache setup that can withstand failures and find the maintenance for uninterrupted facilitation to the application.

Storage type:

MemcacheD stores variables in its memory & retrieves any information directly from the server memory instead of hitting the database again. On the other hand, Redis is like a database that resides in memory. It executes (reads and writes) a key/value pair from its database to return the result set. Developers use Redis for real-time metrics & analytics too.

Read/Write Speed:

MemcacheD is very good to handle high traffic websites. It can read lots of information at a time and give you back at a great response time. Redis can neither handle high traffic on read nor heavy writes.

Data Structure:

MemcacheD uses strings and integers in its data structure. Hence, everything you save can either be one or the other. With integers, the only data manipulation you can do is adding or subtracting them. If you need to save arrays or objects, you will have to serialize them first and then save them. To read them back, you will need to un-serialize.

In comparison Redis has stronger data structures, which can handle not only strings & integers but also binary-safe strings, lists of binary-safe strings, sets of binary-safe strings and sorted sets.

Key Length:

MemcacheD’s key length has a maximum of 250 bytes, whereas Redis has a maximum of 2GB.

Here is the benchmarking result by DB-Engines, which clearly shows the leader.

Conclusion:

Use Redis, if you need to do operations on cached datasets at once or need to spread one enormous cache over a geographically challenged area. Read-write splitting against caching will enormously help performance and alleviate the cache connection starvation.

On the other hand, you might want to stick to Memcached for its simplicity, reliability and speed.

If you’re thinking anything on Ruby on Rails, get in touch with Andolasoft’s experts. Let’s convert your idea into an App.

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Tag: Memcached

How to Boost Performance Of Your Rails App Using DynamoDB And Memcached