[Perf] Make trigger script use python3 print function.

Make the unittests exercise this by adding
    args.multiple_dimension_script_verbose = True
which makes verbose be true everywhere so that we
can make sure the print statements work.

Also add in some additional print statements to clarify what is
happening.

Also fix a couple easy formatting issues.

Bug: 984504, 956637
Change-Id: Ib4dc4236e57f47f0c92eba84db5ae4d9cc969309
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1934526
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Reviewed-by: John Chen <johnchen@chromium.org>
Auto-Submit: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718921}

testing/trigger_scripts/perf_device_trigger.py

@@ -44,6 +44,8 @@ This script is normally called from the swarming recipe module in tools/build.
 
 """
 
+from __future__ import print_function
+
 import argparse
 import copy
 import json
@@ -56,7 +58,7 @@ import urllib
 import base_test_triggerer
 
 class Bot(object):
-  """ Eligible bots to run the task"""
+  """Eligible bots to run the task."""
   def __init__(self, bot_id, is_alive):
     self._bot_id = bot_id
     self._is_alive = is_alive
@@ -161,7 +163,7 @@ class PerfDeviceTriggerer(base_test_triggerer.BaseTestTriggerer):
         shard_to_bot_assignment_map[shard_index] = \
             unallocated_healthy_bots.pop()
         if verbose:
-          print 'First time shard %d has been triggered' % shard_index
+          print('First time shard %d has been triggered' % shard_index)
       elif not bot:
         shard_to_bot_assignment_map[shard_index] = unallocated_bad_bots.pop()
 
@@ -172,8 +174,9 @@ class PerfDeviceTriggerer(base_test_triggerer.BaseTestTriggerer):
         healthy_bot = unallocated_healthy_bots.pop()
         shard_to_bot_assignment_map[shard_index] = healthy_bot
         if verbose:
-          print ('Device affinity broken for bot %s, new '
-                 'mapping to bot %s' % (dead_bot.id(), healthy_bot.id()))
+          print('Device affinity broken for shard #%d. bot %s is dead, new '
+                'mapping to bot %s' % (
+                    shard_index, dead_bot.id(), healthy_bot.id()))
 
     # Now populate the indices into the bot_configs array
     selected_configs = []
@@ -190,17 +193,18 @@ class PerfDeviceTriggerer(base_test_triggerer.BaseTestTriggerer):
 
   def _print_device_affinity_info(
       self, new_map, existing_map, health_map, num_shards):
+    print()
     for shard_index in xrange(num_shards):
       existing = existing_map.get(shard_index, None)
       new = new_map.get(shard_index, None)
-      existing_id = ""
+      existing_id = ''
       if existing:
         existing_id = existing.id()
-      new_id = ""
+      new_id = ''
       if new:
         new_id = new.id()
-      print "Shard %d\n\tprevious: %s\n\tnew: %s" % (
-          shard_index, existing_id, new_id)
+      print('Shard %d\n\tprevious: %s\n\tnew: %s' % (
+          shard_index, existing_id, new_id))
 
     healthy_bots = []
     dead_bots = []
@@ -209,12 +213,16 @@ class PerfDeviceTriggerer(base_test_triggerer.BaseTestTriggerer):
         healthy_bots.append(b.id())
       else:
         dead_bots.append(b.id())
-    print "Healthy bots: %s" % healthy_bots
-    print "Dead Bots: %s" % dead_bots
+    print('Shards needed: %d' % num_shards)
+    print('Total bots (dead + healthy): %d' % (
+        len(dead_bots) + len(healthy_bots)))
+    print('Healthy bots, %d: %s' % (len(healthy_bots), healthy_bots))
+    print('Dead Bots, %d: %s' % (len(dead_bots), dead_bots))
+    print()
 
 
   def _query_swarming_for_eligible_bot_configs(self, dimensions):
-    """ Query Swarming to figure out which bots are available.
+    """Query Swarming to figure out which bots are available.
 
       Returns: a dictionary in which the keys are the bot id and
       the values are Bot object that indicate the health status

testing/trigger_scripts/perf_device_trigger_unittest.py

@@ -58,6 +58,7 @@ class UnitTest(unittest.TestCase):
     args = Args()
     args.shards = len(previous_task_assignment_map)
     args.dump_json = 'output.json'
+    args.multiple_dimension_script_verbose = True
     swarming_args = [
         'trigger',
         '--swarming',
@@ -275,7 +276,7 @@ class UnitTest(unittest.TestCase):
     self.assertIn(expected_task_assignment.get(1), new_healthy_bots)
     self.assertIn(expected_task_assignment.get(2), new_healthy_bots)
 
-  def test_previously_duplicate_task_assignemnts(self):
+  def test_previously_duplicate_task_assignments(self):
     triggerer = self.setup_and_trigger(
         previous_task_assignment_map={0: 'build3', 1: 'build3', 2: 'build5',
                                       3: 'build6'},