Make dmprof handle long runs better

tools/deep_memory_profiler/lib/dump.py

 # Copyright 2013 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.
 
 import copy
 import datetime
 import logging
 import os
 import re
 import time
@@ skipping 389 matching lines @@
     """
     words = stacktrace_line.split()
     if len(words) < BUCKET_ID + 1:
       return False
     if words[BUCKET_ID - 1] != '@':
       return False
     return True
 
 
 class DumpList(object):
-  """Represents a sequence of heap profile dumps."""
+  """Represents a sequence of heap profile dumps.
 
-  def __init__(self, dump_list):
-    self._dump_list = dump_list
+  Individual dumps are loaded into memory lazily as the sequence is accessed,
+  either while being iterated through or randomly accessed.  Loaded dumps are
+  not cached, meaning a newly loaded Dump object is returned every time an
+  element in the list is accessed.
+  """
+
+  def __init__(self, dump_path_list):
+    self._dump_path_list = dump_path_list
 
   @staticmethod
   def load(path_list):
-    LOGGER.info('Loading heap dump profiles.')
-    dump_list = []
-    for path in path_list:
-      dump_list.append(Dump.load(path, '  '))
-    return DumpList(dump_list)
+    return DumpList(path_list)
 
   def __len__(self):
-    return len(self._dump_list)
+    return len(self._dump_path_list)
 
   def __iter__(self):
-    for dump in self._dump_list:
-      yield dump
+    for dump in self._dump_path_list:
+      yield Dump.load(dump)
 
   def __getitem__(self, index):
-    return self._dump_list[index]
+    return Dump.load(self._dump_path_list[index])
 
 
 class ProcMapsEntryAttribute(ExclusiveRangeDict.RangeAttribute):
   """Represents an entry of /proc/maps in range_dict.ExclusiveRangeDict."""
   _DUMMY_ENTRY = procfs.ProcMapsEntry(
       0,     # begin
       0,     # end
       '-',   # readable
       '-',   # writable
       '-',   # executable
@@ skipping 36 matching lines @@
   Returns:
       A pair of an integer indicating a line number after skipped, and a
       boolean value which is True if found a line which skipping_condition
       is False for.
   """
   while skipping_condition(index):
     index += 1
     if index >= max_index:
       return index, False
   return index, True