Reserve a dedicated arena for every construction of mmap_address_map.

third_party/tcmalloc/chromium/src/heap-profiler.cc

Index: third_party/tcmalloc/chromium/src/heap-profiler.cc
diff --git a/third_party/tcmalloc/chromium/src/heap-profiler.cc b/third_party/tcmalloc/chromium/src/heap-profiler.cc
index 85d1aadf7148b80f2a8b8d3c0096cf697dd5f81e..95827b2c79d35a02fef4a26a1ddade13c93bd0c6 100644
--- a/third_party/tcmalloc/chromium/src/heap-profiler.cc
+++ b/third_party/tcmalloc/chromium/src/heap-profiler.cc
@@ -152,6 +152,23 @@ static void ProfilerFree(void* p) {
   LowLevelAlloc::Free(p);
 }
 
+static LowLevelAlloc::Arena *mmap_heap_profiler_memory = NULL;
+
+static void* MMapProfilerMalloc(size_t bytes) {
+  return LowLevelAlloc::AllocWithArena(bytes, mmap_heap_profiler_memory);
+}
+static void MMapProfilerFree(void* p) {
+  LowLevelAlloc::Free(p);
+}
+
+static void DeleteMMapProfilerArenaIfExists() {
+  if (mmap_heap_profiler_memory != NULL) {

[jar (doing other things), 2012/04/04 17:38:40]

nit: Early return tends to improve readability (you don't have to look for the
else or continuation), and reduce indentation of other code.

[Dai Mikurube (NOT FULLTIME), 2012/04/05 05:19:26]

Done.

+    if (!LowLevelAlloc::DeleteArena(mmap_heap_profiler_memory))
+      RAW_LOG(FATAL, "Memory leak in HeapProfiler:");
+    mmap_heap_profiler_memory = NULL;
+  }
+}
+
 // We use buffers of this size in DoGetHeapProfile.
 // The size is 1 << 20 in the original google-perftools.  Changed it to
 // 5 << 20 since a larger buffer is requried for deeper profiling in Chromium.
@@ -200,7 +217,11 @@ static char* DoGetHeapProfileLocked(char* buf, int buflen) {
   int bytes_written = 0;
   if (is_on) {
     if (FLAGS_mmap_profile) {
-      heap_profile->RefreshMMapData();
+      if (mmap_heap_profiler_memory != NULL)
+        DeleteMMapProfilerArenaIfExists();
+      mmap_heap_profiler_memory =
+          LowLevelAlloc::NewArena(0, LowLevelAlloc::DefaultArena());
+      heap_profile->RefreshMMapData(MMapProfilerMalloc, MMapProfilerFree);
     }
     if (deep_profile) {
       bytes_written = deep_profile->FillOrderedProfile(buf, buflen - 1);
@@ -208,7 +229,8 @@ static char* DoGetHeapProfileLocked(char* buf, int buflen) {
       bytes_written = heap_profile->FillOrderedProfile(buf, buflen - 1);
     }
     if (FLAGS_mmap_profile) {
-      heap_profile->ClearMMapData();
+      heap_profile->ClearMMapData(MMapProfilerFree);
+      DeleteMMapProfilerArenaIfExists();
     }
   }
   buf[bytes_written] = '\0';
@@ -532,6 +554,7 @@ extern "C" void HeapProfilerStop() {
 
   // free profile
   heap_profile->~HeapProfileTable();
+  DeleteMMapProfilerArenaIfExists();
   ProfilerFree(heap_profile);
   heap_profile = NULL;