message: [tf.data service] Autotune the number of compress threads.
  Autotune the number of compress threads to prevent compression from becoming the bottleneck.
diff: @@ -467,9 +467,9 @@ def register_dataset(service, dataset):
  # Compress the dataset elements to reduce the amount of data that needs to
  # be sent over the network.
  - # TODO(b/157105111): Make this an autotuned parallel map when we have a way
  - # to limit memory usage.
  - dataset = dataset.map(lambda *x: compression_ops.compress(x))
  + dataset = dataset.map(
  + lambda *x: compression_ops.compress(x),
  + num_parallel_calls=dataset_ops.AUTOTUNE)
  # Prefetch one compressed element to reduce latency when requesting data
  # from tf.data workers.
  # TODO(b/157105111): Set this to autotune when we have a way to limit
  