Initiate the script that takes a snapshot of CPU usage

scripts/slave/recipe_modules/auto_bisect/revision_state.py

 # Copyright 2015 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.
 
 """An interface for holding state and result of revisions in a bisect job.
 
 When implementing support for tests other than perf, one should extend this
 class so that the bisect module and recipe can use it.
 
 See perf_revision_state for an example.
@@ skipping 57 matching lines @@
     self.next_revision = None
     self.previous_revision = None
     self.job_name = None
     self.patch_file = None
     self.deps_revision = None
     self.depot_name = depot_name or self.bisector.base_depot
     self.depot = depot_config.DEPOT_DEPS_NAME[self.depot_name]
     self.commit_hash = str(commit_hash)
     self._rev_str = None
     self.base_revision = base_revision
+    self.snapshot = []
     if self.base_revision:
       assert self.base_revision.deps_file_contents
       self.needs_patch = True
       self.deps_patch, self.deps_file_contents = self.bisector.make_deps_patch(
           self.base_revision, self.base_revision.deps_file_contents,
           self.depot, self.commit_hash)
       self.deps_sha = hashlib.sha1(self.deps_patch).hexdigest()
       self.deps_sha_patch = self.bisector.make_deps_sha_file(self.deps_sha)
       self.deps = dict(base_revision.deps)
       self.deps[self.depot_name] = self.commit_hash
@@ skipping 88 matching lines @@
         'From': lambda *args: None,
     }
     return deps_data
 
   def _read_content(self, url, file_name, branch):   # pragma: no cover
     """Uses gitiles recipe module to download and read file contents."""
     try:
       return self.bisector.api.m.gitiles.download_file(
           repository_url=url, file_path=file_name, branch=branch)
     except TypeError:
-      print 'Could not read content for %s/%s/%s' % (url, file_name, branch) 
+      print 'Could not read content for %s/%s/%s' % (url, file_name, branch)
       return None
 
   def read_deps(self, recipe_tester_name):
     """Sets the dependencies for this revision from the contents of DEPS."""
     api = self.bisector.api
     if self.deps:
       return
     if self.bisector.internal_bisect:  # pragma: no cover
       self.deps_file_contents = self._read_content(
           depot_config.DEPOT_DEPS_NAME[self.depot_name]['url'],
@@ skipping 286 matching lines @@
             'revision_ladder': revision_ladder,
         },
     }
     self.test_results_url = (self.bisector.api.GS_RESULTS_URL +
                              self.job_name + '.results')
     if (api.m.bisect_tester.local_test_enabled() or
         self.bisector.internal_bisect):  # pragma: no cover
       skip_download = self.bisector.last_tested_revision == self
       self.bisector.last_tested_revision = self
       overrides = perf_test_properties['properties']
+      snapshot_result = api.m.step('Take a Snapshot of CPU',
+                        ['python',api.resource('cpu_usage.py')],

[RobertoCN, 2016/06/07 21:44:29]

Alignment. I suggest
... = api.m.step(
    'Take a snapshot of CPU',
    ['python', api.resource('...')],
    stdout=...)

Also space after the comma that goes before api.resource

+                        stdout=api.m.json.output())
+      process_list = snapshot_result.stdout
+      self.snapshot = process_list
+      api.m.step.active_result.presentation.logs['CPU snapshot'] = process_list

[RobertoCN, 2016/06/07 21:44:29]

You need to make sure that process_list is a list of lines so that you can
assign it to result.presentation.logs[...]

       api.run_local_test_run(overrides, skip_download=skip_download)
     else:
       step_name = 'Triggering test job for ' + self.commit_hash
       api.m.trigger(perf_test_properties, name=step_name)
 
   def retest(self):  # pragma: no cover
     # We need at least 5 samples for applying Mann-Whitney U test
     # with P < 0.01, two-tailed .
     target_sample_size =  max(5, math.ceil(len(self.values) * 1.5))
     self.status = RevisionState.NEED_MORE_DATA
@@ skipping 99 matching lines @@
     else:
       next_revision_to_test.retest()
 
   def __repr__(self):
     if self.overall_return_code is not None:
       return ('RevisionState(rev=%s, values=%r, overall_return_code=%r, '
               'std_dev=%r)') % (self.revision_string(), self.values,
                                 self.overall_return_code, self.std_dev)
     return ('RevisionState(rev=%s, values=%r, mean_value=%r, std_dev=%r)' % (
         self.revision_string(), self.values, self.mean_value, self.std_dev))