tools/perf/measurements/v8_detached_context_age_in_gc.py

   1 # Copyright 2015 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import json
   6
   7 from telemetry.page import page_test
   8 from telemetry.value import histogram_util
   9 from telemetry.value import scalar
  10 from telemetry.value import skip
  11
  12 _NAME = 'V8.DetachedContextAgeInGC'
  13 _UNITS = 'garbage_collections'
  14 _DISPLAY_NAME = 'V8_DetachedContextAgeInGC'
  15 _TYPE = histogram_util.RENDERER_HISTOGRAM
  16 _DESCRIPTION = 'Number of GCs needed to collect detached context'
  17
  18
  19 def _GetMaxDetachedContextAge(tab, data_start):
  20   data = histogram_util.GetHistogram(_TYPE, _NAME, tab)
  21   delta = histogram_util.SubtractHistogram(data, data_start)
  22   if not 'buckets' in delta:
  23     return
  24   buckets = json.loads(delta)['buckets']
  25   if buckets:
  26     return max(x.get('high', x['low']) for x in buckets)
  27
  28
  29 class V8DetachedContextAgeInGC(page_test.PageTest):
  30   def __init__(self):
  31     super(V8DetachedContextAgeInGC, self).__init__()
  32     self._data_start = None
  33
  34   def CustomizeBrowserOptions(self, options):
  35     options.AppendExtraBrowserArgs(['--enable-stats-collection-bindings'])
  36
  37   def DidNavigateToPage(self, page, tab):
  38     self._data_start = histogram_util.GetHistogram(_TYPE, _NAME, tab)
  39
  40   def ValidateAndMeasurePage(self, page, tab, results):
  41     # Trigger GC to get histogram data.
  42     # Seven GCs should be enough to collect any detached context.
  43     # If a detached context survives more GCs then there is a leak.
  44     MAX_AGE = 8
  45     for _ in xrange(MAX_AGE):
  46       tab.CollectGarbage()
  47     value = _GetMaxDetachedContextAge(tab, self._data_start)
  48     if value is None:
  49       results.AddValue(skip.SkipValue(
  50           results.current_page, 'No detached contexts'))
  51     else:
  52       results.AddValue(scalar.ScalarValue(
  53           results.current_page, _DISPLAY_NAME, _UNITS, value,
  54           description=_DESCRIPTION))