diff --git a/testing/buildbot/generate_buildbot_json.py b/testing/buildbot/generate_buildbot_json.py
index 90072db..377273fd 100755
--- a/testing/buildbot/generate_buildbot_json.py
+++ b/testing/buildbot/generate_buildbot_json.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -12,6 +12,7 @@
 import collections
 import copy
 import difflib
+import functools
 import glob
 import itertools
 import json
@@ -50,13 +51,17 @@
     raise NotImplementedError()
 
 
+def custom_cmp(a, b):
+  return int(a > b) - int(a < b)
+
+
 def cmp_tests(a, b):
   # Prefer to compare based on the "test" key.
-  val = cmp(a['test'], b['test'])
+  val = custom_cmp(a['test'], b['test'])
   if val != 0:
     return val
   if 'name' in a and 'name' in b:
-    return cmp(a['name'], b['name']) # pragma: no cover
+    return custom_cmp(a['name'], b['name'])  # pragma: no cover
   if 'name' not in a and 'name' not in b:
     return 0 # pragma: no cover
   # Prefer to put variants of the same test after the first one.
@@ -74,7 +79,7 @@
 
   def generate(self, waterfall, tester_name, tester_config, input_tests):
     isolated_scripts = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       test = self.bb_gen.generate_gpu_telemetry_test(
           waterfall, tester_name, tester_config, test_name, test_config,
           self._is_android_webview)
@@ -97,7 +102,7 @@
     # key (see gles2_conform_d3d9_test and similar variants). Avoid
     # losing the order by avoiding coalescing the dictionaries into one.
     gtests = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       # Variants allow more than one definition for a given test, and is defined
       # in array format from resolve_variants().
       if not isinstance(test_config, list):
@@ -112,7 +117,7 @@
     return gtests
 
   def sort(self, tests):
-    return sorted(tests, cmp=cmp_tests)
+    return sorted(tests, key=functools.cmp_to_key(cmp_tests))
 
 
 class IsolatedScriptTestGenerator(BaseGenerator):
@@ -121,7 +126,7 @@
 
   def generate(self, waterfall, tester_name, tester_config, input_tests):
     isolated_scripts = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       # Variants allow more than one definition for a given test, and is defined
       # in array format from resolve_variants().
       if not isinstance(test_config, list):
@@ -144,7 +149,7 @@
 
   def generate(self, waterfall, tester_name, tester_config, input_tests):
     scripts = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       test = self.bb_gen.generate_script_test(
         waterfall, tester_name, tester_config, test_name, test_config)
       if test:
@@ -161,7 +166,7 @@
 
   def generate(self, waterfall, tester_name, tester_config, input_tests):
     scripts = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       test = self.bb_gen.generate_junit_test(
         waterfall, tester_name, tester_config, test_name, test_config)
       if test:
@@ -178,7 +183,7 @@
 
   def generate(self, waterfall, tester_name, tester_config, input_tests):
     scripts = []
-    for test_name, test_config in sorted(input_tests.iteritems()):
+    for test_name, test_config in sorted(input_tests.items()):
       for config in test_config:
         test = self.bb_gen.generate_skylab_test(waterfall, tester_name,
                                                 tester_config, test_name,
@@ -357,7 +362,7 @@
 
   def print_line(self, line):
     # Exists so that tests can mock
-    print line # pragma: no cover
+    print(line)  # pragma: no cover
 
   def read_file(self, relative_path):
     with open(self.generate_abs_file_path(relative_path)) as fp:
@@ -365,7 +370,7 @@
 
   def write_file(self, relative_path, contents):
     with open(self.generate_abs_file_path(relative_path), 'wb') as fp:
-      fp.write(contents)
+      fp.write(contents.encode('utf-8'))
 
   def pyl_file_path(self, filename):
     if self.args and self.args.pyl_files_dir:
@@ -545,7 +550,7 @@
             # swarming dimension_sets that we have to merge. It will fail
             # to merge / override 'args' arrays which are different
             # length.
-            for idx in xrange(len(b[key])):
+            for idx in range(len(b[key])):
               try:
                 a[key][idx] = self.dictionary_merge(a[key][idx], b[key][idx],
                                                     path + [str(key), str(idx)],
@@ -637,7 +642,7 @@
         del swarming_dict['hard_timeout'] # pragma: no cover
     if not swarming_dict.get('can_use_on_swarming_builders', False):
       # Remove all other keys.
-      for k in swarming_dict.keys(): # pragma: no cover
+      for k in list(swarming_dict):  # pragma: no cover
         if k != 'can_use_on_swarming_builders': # pragma: no cover
           del swarming_dict[k] # pragma: no cover
 
@@ -667,12 +672,12 @@
     replacements = self.get_test_replacements(
         test, test_name, tester_name) or {}
     valid_replacement_keys = ['args', 'non_precommit_args', 'precommit_args']
-    for key, replacement_dict in replacements.iteritems():
+    for key, replacement_dict in replacements.items():
       if key not in valid_replacement_keys:
         raise BBGenErr(
             'Given replacement key %s for %s on %s is not in the list of valid '
             'keys %s' % (key, test_name, tester_name, valid_replacement_keys))
-      for replacement_key, replacement_val in replacement_dict.iteritems():
+      for replacement_key, replacement_val in replacement_dict.items():
         found_key = False
         for i, test_key in enumerate(test.get(key, [])):
           # Handle both the key/value being replaced being defined as two
@@ -1006,7 +1011,7 @@
     other_suites = self.test_suites.get(other_test_type, {})
     basic_suites = self.test_suites.get('basic_suites', {})
 
-    for suite, suite_def in target_suites.iteritems():
+    for suite, suite_def in target_suites.items():
       if suite in basic_suites:
         raise BBGenErr('%s names may not duplicate basic test suite names '
                        '(error found while processsing %s)'
@@ -1031,13 +1036,13 @@
     new_test_suites = {}
     test_types = ['basic_suites', 'compound_suites', 'matrix_compound_suites']
     for category in test_types:
-      for name, value in self.test_suites.get(category, {}).iteritems():
+      for name, value in self.test_suites.get(category, {}).items():
         new_test_suites[name] = value
     self.test_suites = new_test_suites
 
   def resolve_test_id_prefixes(self):
-    for suite in self.test_suites['basic_suites'].itervalues():
-      for key, test in suite.iteritems():
+    for suite in self.test_suites['basic_suites'].values():
+      for key, test in suite.items():
         assert isinstance(test, dict)
 
         # This assumes the recipe logic which prefers 'test' to 'isolate_name'
@@ -1074,7 +1079,7 @@
     # referenced by compound suites exist.
     basic_suites = self.test_suites.get('basic_suites')
 
-    for name, value in compound_suites.iteritems():
+    for name, value in compound_suites.items():
       # Resolve this to a dictionary.
       full_suite = {}
       for entry in value:
@@ -1103,7 +1108,7 @@
 
     # Each test in a basic test suite will have a definition per variant.
     test_suite = {}
-    for test_name, test_config in basic_test_definition.iteritems():
+    for test_name, test_config in basic_test_definition.items():
       definitions = []
       for variant in variants:
         # Unpack the variant from variants.pyl if it's string based.
@@ -1164,10 +1169,10 @@
     # referenced by matrix suites exist.
     basic_suites = self.test_suites.get('basic_suites')
 
-    for test_name, matrix_config in matrix_compound_suites.iteritems():
+    for test_name, matrix_config in matrix_compound_suites.items():
       full_suite = {}
 
-      for test_suite, mtx_test_suite_config in matrix_config.iteritems():
+      for test_suite, mtx_test_suite_config in matrix_config.items():
         basic_test_def = copy.deepcopy(basic_suites[test_suite])
 
         if 'variants' in mtx_test_suite_config:
@@ -1180,8 +1185,8 @@
 
   def link_waterfalls_to_test_suites(self):
     for waterfall in self.waterfalls:
-      for tester_name, tester in waterfall['machines'].iteritems():
-        for suite, value in tester.get('test_suites', {}).iteritems():
+      for tester_name, tester in waterfall['machines'].items():
+        for suite, value in tester.get('test_suites', {}).items():
           if not value in self.test_suites:
             # Hard / impossible to cover this in the unit test.
             raise self.unknown_test_suite(
@@ -1370,9 +1375,8 @@
       A dictionary mapping builders to test specs
       """
     return {
-      name: self.get_tests_for_config(waterfall, name, config)
-        for name, config
-        in waterfall['machines'].iteritems()
+        name: self.get_tests_for_config(waterfall, name, config)
+        for name, config in waterfall['machines'].items()
     }
 
   def get_tests_for_config(self, waterfall, name, config):
@@ -1385,7 +1389,7 @@
     if 'additional_compile_targets' in config:
       tests['additional_compile_targets'] = config[
         'additional_compile_targets']
-    for test_type, input_tests in config.get('test_suites', {}).iteritems():
+    for test_type, input_tests in config.get('test_suites', {}).items():
       if test_type not in generator_map:
         raise self.unknown_test_suite_type(
           test_type, name, waterfall['name']) # pragma: no cover
@@ -1581,8 +1585,8 @@
     suites_seen = set()
     generator_map = self.get_test_generator_map()
     for waterfall in self.waterfalls:
-      for bot_name, tester in waterfall['machines'].iteritems():
-        for suite_type, suite in tester.get('test_suites', {}).iteritems():
+      for bot_name, tester in waterfall['machines'].items():
+        for suite_type, suite in tester.get('test_suites', {}).items():
           if suite_type not in generator_map:
             raise self.unknown_test_suite_type(suite_type, bot_name,
                                                waterfall['name'])
@@ -1607,17 +1611,17 @@
     all_bots = set()
     missing_bots = set()
     for waterfall in self.waterfalls:
-      for bot_name, tester in waterfall['machines'].iteritems():
+      for bot_name, tester in waterfall['machines'].items():
         all_bots.add(bot_name)
         # In order to disambiguate between bots with the same name on
         # different waterfalls, support has been added to various
         # exceptions for concatenating the waterfall name after the bot
         # name.
         all_bots.add(bot_name + ' ' + waterfall['name'])
-    for exception in self.exceptions.itervalues():
+    for exception in self.exceptions.values():
       removals = (exception.get('remove_from', []) +
                   exception.get('remove_gtest_from', []) +
-                  exception.get('modifications', {}).keys())
+                  list(exception.get('modifications', {}).keys()))
       for removal in removals:
         if removal not in all_bots:
           missing_bots.add(removal)
@@ -1631,7 +1635,7 @@
     seen_mixins = set()
     for waterfall in self.waterfalls:
       seen_mixins = seen_mixins.union(waterfall.get('mixins', set()))
-      for bot_name, tester in waterfall['machines'].iteritems():
+      for bot_name, tester in waterfall['machines'].items():
         seen_mixins = seen_mixins.union(tester.get('mixins', set()))
     for suite in self.test_suites.values():
       if isinstance(suite, list):
@@ -2090,7 +2094,7 @@
     configuration, not grouped by their test suite.
     """
     tests = {}
-    for test_suite in test_suites.itervalues():
+    for test_suite in test_suites.values():
       for test in test_suite:
         test_info = test_suite[test]
         test_name = test