Fix lint errors

examples/python/multiprocessing/client.py

@@ -19,14 +19,13 @@ from __future__ import print_function
 
 import argparse
 import atexit
-import grpc
 import logging
 import multiprocessing
 import operator
-import os
-import time
 import sys
 
+import grpc
+
 import prime_pb2
 import prime_pb2_grpc
 
@@ -34,15 +33,23 @@ _PROCESS_COUNT = 8
 _MAXIMUM_CANDIDATE = 10000
 
 # Each worker process initializes a single channel after forking.
+# It's regrettable, but to ensure that each subprocess only has to instantiate
+# a single channel to be reused across all RPCs, we use globals.
 _worker_channel_singleton = None
 _worker_stub_singleton = None
 
 _LOGGER = logging.getLogger(__name__)
 
 
+def _shutdown_worker():
+    _LOGGER.info('Shutting worker process down.')
+    if _worker_channel_singleton is not None:
+        _worker_channel_singleton.stop()
+
+
 def _initialize_worker(server_address):
-    global _worker_channel_singleton
+    global _worker_channel_singleton  # pylint: disable=global-statement
-    global _worker_stub_singleton
+    global _worker_stub_singleton  # pylint: disable=global-statement
     _LOGGER.info('Initializing worker process.')
     _worker_channel_singleton = grpc.insecure_channel(server_address)
     _worker_stub_singleton = prime_pb2_grpc.PrimeCheckerStub(
@@ -50,14 +57,8 @@ def _initialize_worker(server_address):
     atexit.register(_shutdown_worker)
 
 
-def _shutdown_worker():
-    _LOGGER.info('Shutting worker process down.')
-    if _worker_channel_singleton is not None:
-        _worker_channel_singleton.stop()
-
-
 def _run_worker_query(primality_candidate):
-    _LOGGER.info('Checking primality of {}.'.format(primality_candidate))
+    _LOGGER.info('Checking primality of %s.', primality_candidate)
     return _worker_stub_singleton.check(
         prime_pb2.PrimeCandidate(candidate=primality_candidate))
 

examples/python/multiprocessing/server.py

@@ -20,15 +20,15 @@ from __future__ import print_function
 from concurrent import futures
 import contextlib
 import datetime
-import grpc
 import logging
 import math
 import multiprocessing
-import os
 import time
 import socket
 import sys
 
+import grpc
+
 import prime_pb2
 import prime_pb2_grpc
 
@@ -50,7 +50,7 @@ def is_prime(n):
 class PrimeChecker(prime_pb2_grpc.PrimeCheckerServicer):
 
     def check(self, request, context):
-        _LOGGER.info('Determining primality of {}'.format(request.candidate))
+        _LOGGER.info('Determining primality of %s', request.candidate)
         return prime_pb2.Primality(isPrime=is_prime(request.candidate))
 
 
@@ -99,7 +99,7 @@ def _reserve_port():
 def main():
     with _reserve_port() as port:
         bind_address = '[::]:{}'.format(port)
-        _LOGGER.info("Binding to '{}'".format(bind_address))
+        _LOGGER.info("Binding to '%s'", bind_address)
         sys.stdout.flush()
         workers = []
         for _ in range(_PROCESS_COUNT):

examples/python/multiprocessing/test/_multiprocessing_example_test.py

@@ -13,14 +13,13 @@
 # limitations under the License.
 """Test for multiprocessing example."""
 
-import datetime
+import ast
 import logging
 import math
 import os
 import re
 import subprocess
 import tempfile
-import time
 import unittest
 
 _BINARY_DIR = os.path.realpath(
@@ -63,7 +62,7 @@ class MultiprocessingExampleTest(unittest.TestCase):
         client_process.wait()
         server_process.terminate()
         client_stdout.seek(0)
-        results = eval(client_stdout.read().strip().split('\n')[-1])
+        results = ast.literal_eval(client_stdout.read().strip().split('\n')[-1])
         values = tuple(result[0] for result in results)
         self.assertSequenceEqual(range(2, 10000), values)
         for result in results: