What is the role of `spark.memory.fraction` in managing memory usage?

The `spark.memory.fraction` property controls the fraction of the JVM heap that is allocated to Spark's storage and execution. Setting it to 0.8 (or a similar value) allocates 80% of the available memory to the storage engine (RDDs, DataFrames, etc.) and 20% to the execution engine (Spark tasks). Adjusting this value can significantly impact memory usage.