Performance issues in the program

[DLPerf]

Hello,I found a performance issue in the definition of input_fn ,
TensorFlowOnSpark/blob/master/examples/mnist/estimator/mnist_spark_streaming.py,
return ds.map(scale) was called without num_parallel_calls.
I think it will increase the efficiency of your program if you add this.

The same issues also exist in ds.map(scale) and ds.map(scale)

Here is the documemtation of tensorflow to support this thing.

Looking forward to your reply. Btw, I am very glad to create a PR to fix it if you are too busy.

[leewyang]

closing bot activity.

[DLPerf]

Hello,is anyone here?