Shuffle uses Direct Memory Buffer even after setting "spark.shuffle.io.preferDirectBufs = false"
I am using Standalone Spark 2.3 and have a question regarding Shuffle. Going by the documentation, default Shuffle behaviour is to use Direct Memory buffers. But, even after I set the following parameter, I notice Shuffle still uses Direct Memory buffers.
spark.shuffle.io.preferDirectBufs = false
Is this a bug ? How can I disable use of Direct Memory for Shuffle