Is it true that applications written in any programming language can run on Hadoop MapReduce?

Hadoop MapReduce is primarily designed to work with Java, as it is written in Java and provides the core API and framework for handling data processing in a distributed environment. While it's true that Hadoop can support applications written in other programming languages through various interfaces and tools, the statement that applications written in any programming language can run on Hadoop MapReduce is misleading. The main execution model and the built-in support provided by Hadoop to run MapReduce jobs are heavily based on Java.

To enable the use of other programming languages, such as Python or Ruby, you would typically rely on additional layers or frameworks, like Apache Streaming, which allows developers to write Mapper and Reducer programs in different languages. However, this does not mean that all programming languages can directly run on Hadoop without some form of integration or support.

Thus, the assertion that applications in any programming language can seamlessly run on Hadoop MapReduce is false, as it fundamentally relies on Java for its core functionalities and operations.