What is the primary purpose of using broadcast variables in Spark?

The primary purpose of using broadcast variables in Spark is indeed to send a read-only variable to all nodes. This is particularly useful when the same data needs to be accessed by multiple tasks across different nodes in the cluster. By broadcasting a variable, Spark allows each node to have a local copy of this variable, which minimizes the amount of data transferred over the network. As a result, it enhances performance by reducing the overhead associated with data transfer, allowing tasks to access the variable more quickly.

Broadcast variables are especially beneficial in scenarios where the dataset being shared among the nodes is too large to be sent individually to each task, as they ensure that the data is only sent once and reused across various tasks. This not only conserves resources but also improves the efficiency of distributed computation in Spark applications.