What is the programming model and best language for Hadoop and Spark? Python or Java?

Hadoop is an open-source software framework for storing data and running applications on clusters of commodity hardware. It provides massive storage for any kind of data, enormous processing power and the ability to handle virtually limitless concurrent tasks or jobs. Apache Hadoop is used mainly for Data Analysis. 

Apache Spark is an open-source distributed general-purpose cluster-computing framework. Spark provides an interface for programming entire clusters with implicit data parallelism and fault tolerance. 

The question is Which programming language is good to drive Hadoop and Spark?

The programming model for developing hadoop based applications is the map reduce. In other words, MapReduce is the processing layer of Hadoop.
MapReduce programming model is designed for processing large volumes of data in parallel by dividing the work into a set of independent tasks. Hadoop MapReduce is a software framework for easily writing an application that processes the vast amount of structured and unstructured data stored in the Hadoop Distributed FileSystem (HDFS). The biggest advantage of map reduce is to make data processing on multiple computing nodes easy. Under the Map reduce model, data processing primitives are called Mapper and Reducers.

Spark is written in Scala and Hadoop is written in Java.

The key difference between Hadoop MapReduce and Spark lies in the approach to processing: Spark can do it in-memory, while Hadoop MapReduce has to read from and write to a disk. As a result, the speed of processing differs significantly – Spark may be up to 100 times faster.

In-memory processing is faster when compared to Hadoop, as there is no time spent in moving data/processes in and out of the disk. Spark is 100 times faster than MapReduce as everything is done here in memory.

Spark’s hardware is more expensive than Hadoop MapReduce because it’s hardware needs a lot of RAM.

Hadoop runs on Linux, it means that you must have knowldge of linux.

Java is important for hadoop because:

• There are some advanced features that are only available via the Java API.
• The ability to go deep into the Hadoop coding and figure out what’s going wrong.

In both these situations, Java becomes very important.
As a developer, you can enjoy many advanced features of Spark and Hadoop if you start with their native languages (Java and Scala).

What Python Offers for Hadoop and Spark?

• Simple syntax– Python offers simple syntax which shows it is more user friendly than other two languages.
• Easy to learn – Python syntax are like English languages. So, it much more easier to learn it and master it.
• Large community support – Unlike Scala, Python has huge community (active), which we will help you to solve your queries.
• Offers Libraries, frameworks and packages – Python has huge number of Scientific packages, libraries and framework, which are helping you to work in any environment of Hadoop and Spark.
• Python Compatibility with Hadoop – A package called PyDoop offers access to the HDFS API for Hadoop and hence it allows to write Hadoop MapReduce program and application.

• Hadoop is based off of Java (then so e.g. non-Hadoop yet still a Big-Data technology like the ElasticSearch engine, too – even though it processes JSON REST requests)
• Spark is created off of Scala although pySpark (the lovechild of Python and Spark technologies of course) has gained a lot of momentum as of late.

If you are planning for Hadoop Data Analyst, Python is preferable given that it has many libraries to perform advanced analytics and also you can use Spark to perform advanced analytics and implement machine learning techniques using pyspark API.

The key Value pair is the record entity that MapReduce job receives for execution. In MapReduce process, before passing the data to the mapper, data should be first converted into key-value pairs as mapper only understands key-value pairs of data.
key-value pairs in Hadoop MapReduce is generated as follows:

Resources:

1- Quora

2- Wikipedia

3- Data Flair