A deeper heap profile dumper in third_party/tcmalloc/chromium.

third_party/tcmalloc/chromium/src/deep-heap-profile.h

+// Copyright (c) 2011 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.
+
+// ---
+// Author: Sainbayar Sukhbaatar
+//         Dai Mikurube
+//
+// This file contains a class DeepHeapProfile and its public function
+// DeepHeapProfile::FillOrderedProfile() which works as an alternative of
+// HeapProfileTable::FillOrderedProfile().
+//
+// DeepHeapProfile::FillOrderedProfile() dumps more detailed information about
+// heap usage, which includes OS-level information such as whether the memory
+// block is actually in memory, or not.  DeepHeapProfile::FillOrderedProfile()
+// uses logged data in HeapProfileTable as one of its data sources.
+// DeepHeapProfile works only when its FillOrderedProfile() is called.  It has
+// overhead when dumping, but no overhead when logging.
+//
+// It currently works only on Linux.  It just delegates to HeapProfileTable in
+// non-Linux environments.
+
+
+#ifndef BASE_DEEP_HEAP_PROFILE_H_
+#define BASE_DEEP_HEAP_PROFILE_H_
+
+#include "config.h"
+
+#if defined(__linux__)
+#define DEEP_HEAP_PROFILE 1
+#endif
+
+#include "addressmap-inl.h"
+#include "heap-profile-table.h"
+
+class DeepHeapProfile {
+ public:
+  typedef HeapProfileTable::Bucket Bucket;
+  typedef HeapProfileTable::AllocationMap AllocationMap;
+  typedef HeapProfileTable::AllocValue AllocValue;
+  typedef HeapProfileTable::Stats Stats;
+
+  // Construct a DeepHeapProfile instance.  It works as a wrapper of
+  // HeapProfileTable.
+  //
+  // 'heap_profile' is a pointer to HeapProfileTable.  DeepHeapProfile reads
+  // data in 'heap_profile' and forwards operations to 'heap_profile' if
+  // DeepHeapProfile is not available (non-Linux).
+  // 'prefix' is a prefix of dumped file names.
+  DeepHeapProfile(HeapProfileTable* heap_profile, const char* prefix);
+  ~DeepHeapProfile();
+
+  // Fill deep profile data into buffer 'buffer' of size 'size', and return the
+  // actual size occupied by the dump in 'buffer'.  It works as an alternative
+  // of HeapProfileTable::FillOrderedProfile.
+  //
+  // The profile buckets are dumped in the decreasing order of currently
+  // allocated bytes.  We do not provision for 0-terminating 'buffer'.
+  int FillOrderedProfile(char buffer[], int buffer_size);

[jar (doing other things), 2012/01/27 00:46:58]

It appears that the |buffer| is nothing more than a temporary work area. 
Certainly no data can be returned, as there is no API for indicating what was/is
used.  Given that it is a temp area, why don't you stack allocate in
FillOrderedProfile()?

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

One reason is that the original heap-profiler is already using such a buffer. 
HeapProfiler already has such a buffer  for
HeapProfileTable::FillOrderedProfile.  DeepHeapProfile uses it.

The second reason is that a filled content, actually, can be returned through
the buffer.  Please look at an external API GetHeapProfile() in
heap-profiler.cc, which is in the original heap-profiler.  It returns the
buffer.  (I don't think it's so good to return malloc'ed pointer, though...)

Third, allocation cost though it's just a small reason.  FillOrderedProfile is
called many times.

At last, a malloc'ed and fixed buffer can be easily caught by the profiler
itself.  We can estimate how large memory is used by the profiler.

On 2012/01/27 00:46:58, jar wrote:

+
+ private:
+#ifdef DEEP_HEAP_PROFILE
+  struct DeepBucket {
+    Bucket* bucket;
+    size_t committed_size;
+    int   id;         // Unique ID of the bucket.
+    bool  is_logged;  // True if the stracktrace is logged to a file.
+  };
+
+  typedef AddressMap<DeepBucket> DeepBucketMap;
+
+  struct PageState {
+    bool is_committed;  // Currently, we use only this
+    bool is_present;
+    bool is_swapped;
+    bool is_shared;
+    bool is_mmap;
+  };
+
+  struct RegionStats {

[jar (doing other things), 2012/01/27 00:46:58]

Please make this into a class, and then rename the slots to end in an
underscore.  

The methods are now more than complex enough to warrant a class, and it will
help with readability.

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Agreed.  Done it.

On 2012/01/27 00:46:58, jar wrote:

+    size_t virtual_bytes;
+    size_t committed_bytes;
+
+    // Initialize 'virtual_bytes' and 'committed_bytes'.
+    void Initialize();
+
+    // Update the RegionStats to include the tallies of virtual_bytes and
+    // committed_bytes in the region from 'first_adress' to 'last_address'
+    // inclusive.
+    void Record(int pagemap_fd, uint64 first_address, uint64 last_address);
+  };
+
+  struct GlobalStats {
+    // All RegionStats members in this class contain the bytes of virtual
+    // memory and committed memory.
+    // TODO(dmikurube): These regions should be classified more precisely later
+    // for more detailed analysis.
+
+    // Total bytes of the process memory.
+    RegionStats total;
+
+    // Total bytes of memory which is mapped to a file.
+    // Regions which contain file paths in the last column of /proc/<pid>/maps.
+    RegionStats file_mapped;
+
+    // Total bytes of memory which is mapped anonymously.
+    // Regions which contain nothing in the last column of /proc/<pid>/maps.
+    RegionStats anonymous;
+
+    // Total bytes of memory which is labeled, but not mapped to any file.
+    // Regions which contain non-path strings in the last column of
+    // /proc/<pid>/maps.
+    RegionStats other;
+
+    // Total bytes of mmap'ed regions.
+    RegionStats record_mmap;
+
+    // Total bytes of malloc'ed regions.
+    RegionStats record_malloc;
+  };
+
+  // Clear the 'is_logged' flag in a DeepBucket object as a callback function
+  // for DeepBucketMap::Iterate().
+  static void ClearIsLogged(const void* pointer, DeepBucket* db,

[jar (doing other things), 2012/01/27 00:46:58]

nit: one arg per line.

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Done.

+                            DeepHeapProfile* deep_profile);
+
+  // Open /proc/pid/pagemap and return its file descriptor.
+  // File descriptors need to be refreshed after each fork.
+  static int OpenProcPagemap();
+
+  // Seek to the offset of the open pagemap file pagemap_fd.
+  // It returns true if succeeded.  Otherwise, it returns false.
+  static bool SeekProcPagemap(int pagemap_fd, uint64 address);
+
+  // Read a pagemap state from the current pagemap_fd offset.
+  // It returns true if succeeded.  Otherwise, it returns false.
+  static bool ReadProcPagemap(int pagemap_fd, PageState* state);
+
+  // Returns the number of resident (including swapped) bytes of the memory
+  // region starting at 'first_address' and ending at 'last_address' inclusive.
+  static size_t GetCommittedSize(int pagemap_fd,
+                                 uint64 first_address,
+                                 uint64 last_address);
+
+  // Write re-formatted /proc/self/maps into a file which has 'filename_prefix'
+  // with using 'buffer' of size 'buffer_size'.
+  static void WriteMapsToFile(char buffer[], int buffer_size,
+                              char* filename_prefix);
+
+  // Compute the global statistics from /proc/self/maps and 'pagemap_fd', and
+  // store the statistics in 'stats'.
+  static void GetGlobalStats(int pagemap_fd, GlobalStats* stats);

[jar (doing other things), 2012/01/27 00:46:58]

This was made a static method... but I think it all cases we call it with a slot
from a specific instance.  Why isn't this a non-static member function, that
simply accesses pagemap_fd_?

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Because I (myself) sometimes confused where GetGlobalStats get information
from...  Making all pagemap-related functions static with |pagemap_fd| helps us
to understand they're reading from pagemap easily.

+
+  // Get the DeepBucket object corresponding to the given 'bucket'.
+  // DeepBucket is an extension to Bucket which is declared above.
+  DeepBucket* GetDeepBucket(Bucket* bucket);
+
+  // Reset committed_size member variables in DeepBucket objects to 0.
+  void ResetCommittedSize(Bucket** bucket_table);
+
+  // Fill bucket data in 'table' into buffer 'buffer' of size 'size', and return
+  // the size occupied by the bucket data in 'buffer'.  'bucket_length' is the
+  // offset for 'buffer' to start filling.  Statistics in 'stats' is updated if
+  // it's not NULL.
+  int FillBucketTable(Bucket** bucket_table, char buffer[], int buffer_size,

[jar (doing other things), 2012/01/27 00:46:58]

nit: if declaration can't put the whole thing on one line, then put one arg per
line (unless the args group together).

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Done.

+                      int bucket_length, HeapProfileTable::Stats* stats);
+
+  // Record both virtual and committed byte counts of malloc and mmap regions
+  // as callback functions for AllocationMap::Iterate().
+  static void RecordAlloc(const void* pointer, AllocValue* alloc_value,

[jar (doing other things), 2012/01/27 00:46:58]

nit: one arg per line

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Done.

+                          DeepHeapProfile* deep_profile);
+  static void RecordMMap(const void* pointer, AllocValue* alloc_value,
+                         DeepHeapProfile* deep_profile);
+  void RecordAllAllocs();
+
+  // Fill a bucket (a bucket id and its corresponding calling stack) into
+  // 'buffer' of size 'buffer_size'.
+  int FillBucketForBucketFile(const DeepBucket* deep_bucket,

[jar (doing other things), 2012/01/27 00:46:58]

nit: modified arg |deep_bucket| should be last in list.

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

What do you mean by 'modified'?  |deep_bucket| is a constant used to give
information to write into buffer.

[jar (doing other things), 2012/03/16 01:20:02]

I was mistaken about |deep_bucket|.  Sorry.

|buffer| is what is being modified and should probably be last... and it looks
like you've moved it. Thanks!

On 2012/01/30 12:54:53, Dai Mikurube wrote:

+                              char buffer[],
+                              int buffer_size);
+
+  // Write a bucket table 'table' into a file of 'bucket_fd'.
+  void WriteBucketsTableToBucketFile(Bucket** table, RawFD bucket_fd);
+
+  // Write both malloc and mmap bucket tables into "a bucket file".
+  void WriteBucketsToBucketFile();
+
+  // Fill a (deep) bucket into 'buffer' from the offset 'used_in_buffer'.
+  // Add the sizes to 'profile_stats' if it's not NULL.
+  static int UnparseBucket(const DeepBucket& b,
+                           char* buffer, int used_in_buffer, int buffer_size,
+                           const char* extra,
+                           Stats* profile_stats);
+
+  // Fill statistics of a region into 'buffer'.
+  static int UnparseRegionStats(const RegionStats* stats,
+                                const char* name,
+                                char* buffer,
+                                int used_in_buffer,
+                                int buffer_size);

[jar (doing other things), 2012/01/27 00:46:58]

nit: buffer should be the last arg (since it is modified).  

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Done for it and other functions, except for FillOrderedProfile.

Kept FillOrderedProfile to be consistent with
HeapProfileTable::FillOrderedProfile.  At least it should have the same
interface with HeapProfileTable.

+
+  // Fill global statistics into 'buffer'.
+  int UnparseGlobalStats(char* buffer, int used_in_buffer, int buffer_size);

[jar (doing other things), 2012/01/27 00:46:58]

nit: When a method modifies values, the values that are modified come at the end
of the list of args.  In this case, presumably |buffer| should be last.

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Done.

+
+#endif  // DEEP_HEAP_PROFILE
+  HeapProfileTable* heap_profile_;
+#ifdef DEEP_HEAP_PROFILE
+
+  int pagemap_fd_;         // File descriptor of /proc/self/pagemap.
+  pid_t most_recent_pid_;  // Process ID of the last dump.  This could change.

[jar (doing other things), 2012/01/27 00:46:58]

How does this change? fork?

[Dai Mikurube (NOT FULLTIME), 2012/01/30 12:54:53]

Yes.  Added a comments.

+  GlobalStats stats_;      // Stats about total memory.
+  int dump_count_;         // The number of dumps.
+  char* filename_prefix_;  // Output file prefix.
+  char* profiler_buffer_;  // Buffer we use many times.
+
+  int bucket_id_;
+  DeepBucketMap* deep_bucket_map_;
+#endif  // DEEP_HEAP_PROFILE
+
+  DISALLOW_COPY_AND_ASSIGN(DeepHeapProfile);
+};
+
+#endif  // BASE_DEEP_HEAP_PROFILE_H_