Update the importing logic for cpuinfo and psutil. (#3781)

* Update the importing logic for cpuinfo and psutil.

Those two libs are usually not installed by default, and we should
not force people to install them if they just want to run resnet.

* Add pylint warning suppression.

official/utils/logging/logger.py

@@ -28,13 +28,6 @@ import multiprocessing
 import numbers
 import os
 
-# pylint: disable=g-bad-import-order
-# Note: cpuinfo and psutil are not installed in the TensorFlow OSS tree.
-# They are installable via pip.
-import cpuinfo
-import psutil
-# pylint: enable=g-bad-import-order
-
 import tensorflow as tf
 from tensorflow.python.client import device_lib
 
@@ -149,6 +142,10 @@ def _collect_cpu_info(run_info):
 
   cpu_info["num_cores"] = multiprocessing.cpu_count()
 
+  # Note: cpuinfo is not installed in the TensorFlow OSS tree.
+  # It is installable via pip.
+  import cpuinfo    # pylint: disable=g-import-not-at-top
+
   info = cpuinfo.get_cpu_info()
   cpu_info["cpu_info"] = info["brand"]
   cpu_info["mhz_per_cpu"] = info["hz_advertised_raw"][0] / 1.0e6
@@ -175,6 +172,9 @@ def _collect_gpu_info(run_info):
 
 
 def _collect_memory_info(run_info):
+  # Note: psutil is not installed in the TensorFlow OSS tree.
+  # It is installable via pip.
+  import psutil   # pylint: disable=g-import-not-at-top
   vmem = psutil.virtual_memory()
   run_info["memory_total"] = vmem.total
   run_info["memory_available"] = vmem.available