"Among the clients of the Spark runtime architecture, Scala is the most popular language, followed by Python and Java. According to a recent survey by Databricks, the company behind Apache Spark, 71% of respondents reported using Scala for Spark development, while Python was used by 24% and Java by 5%. Another survey by Typesafe on the Spark ecosystem revealed that 88% of respondents used Scala, 44% used Java, and 22% used Python, with the percentages reflecting multiple language usage. Scala is considered the most optimized language for Spark due to its integration with the JVM and its role as the language in which Spark was internally implemented, offering better performance and access to the latest features."