Oilpan: Implement mark/sweep stats collection for free list profiler.

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index be833d48df1d3d438cf739bb075f529a3b73b55b..131b6afdda68f89849f4416e59320b4756a3aa33 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -670,6 +670,12 @@ void ThreadState::snapshot()
 
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID("blink_gc", "ThreadState", this, json.release());
 }
+
+void ThreadState::incrementMarkedObjectsAge()
+{
+    for (int i = 0; i < NumberOfHeaps; ++i)
+        m_heaps[i]->incrementMarkedObjectsAge();
+}
 #endif
 
 void ThreadState::pushWeakPointerCallback(void* object, WeakPointerCallback callback)
@@ -990,6 +996,25 @@ void ThreadState::preGC()
 void ThreadState::postGC(GCType gcType)
 {
     ASSERT(isInGC());
+
+#if ENABLE(GC_PROFILING)
+    // We snapshot the heap prior to sweeping to get numbers for both resources
+    // that have been allocated since the last GC and for resources that are
+    // going to be freed.
+    bool gcTracingEnabled;
+    TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink_gc", &gcTracingEnabled);
+
+    if (gcTracingEnabled) {
+        bool disabledByDefaultGCTracingEnabled;
+        TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("blink_gc"), &disabledByDefaultGCTracingEnabled);
+
+        snapshot();
+        if (disabledByDefaultGCTracingEnabled)
+            collectAndReportMarkSweepStats();
+        incrementMarkedObjectsAge();
+    }
+#endif
+
     setGCState(gcType == GCWithSweep ? EagerSweepScheduled : LazySweepScheduled);
     for (int i = 0; i < NumberOfHeaps; i++)
         m_heaps[i]->prepareForSweep();
@@ -1130,16 +1155,6 @@ void ThreadState::postGCProcessing()
 
     m_didV8GCAfterLastGC = false;
 
-#if ENABLE(GC_PROFILING)
-    // We snapshot the heap prior to sweeping to get numbers for both resources
-    // that have been allocated since the last GC and for resources that are
-    // going to be freed.
-    bool gcTracingEnabled;
-    TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink_gc", &gcTracingEnabled);
-    if (gcTracingEnabled)
-        snapshot();
-#endif
-
     {
         if (isMainThread())
             ScriptForbiddenScope::enter();
@@ -1300,6 +1315,34 @@ void ThreadState::snapshotFreeList()
 
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), "FreeList", this, json.release());
 }
+
+void ThreadState::collectAndReportMarkSweepStats() const
+{
+    if (!isMainThread())

[haraken, 2015/02/06 06:39:20]

Why do we need to have the isMainThread check? ThreadState::postGC() is called
only by one GCing thread (which may not be the main thread), meaning that
collectAndReportMarkSweepStats() is called only by the thread. Thus we don't
need to worry about thread races.

[Yuta Kitamura, 2015/02/06 07:45:45]

The reason is that data from non-main thread makes
the graph look strange (many objects are marked/swept in
main threads, while almost zero objects are marked/swept
in non-main threads, making the graph look zig-zag).

In the long term, we could extend the data format and
keishi's dashboard to allow thread-specific counts, but
that's something that we don't have right now AFAIK.

[haraken, 2015/02/06 07:51:50]

Thanks, makes sense.

[keishi, 2015/02/06 08:21:07]

All records in the trace json file have tid fields and I did write code to
filter out non main thread records. If this makes a difference I think that
would be a bug in my viewer.

+        return;
+
+    ClassAgeCountsMap markingClassAgeCounts;
+    for (int i = 0; i < NumberOfHeaps; ++i)
+        m_heaps[i]->countMarkedObjects(markingClassAgeCounts);
+    reportMarkSweepStats("MarkingStats", markingClassAgeCounts);
+
+    ClassAgeCountsMap sweepingClassAgeCounts;
+    for (int i = 0; i < NumberOfHeaps; ++i)
+        m_heaps[i]->countObjectsToSweep(sweepingClassAgeCounts);
+    reportMarkSweepStats("SweepingStats", sweepingClassAgeCounts);
+}
+
+void ThreadState::reportMarkSweepStats(const char* statsName, const ClassAgeCountsMap& classAgeCounts) const
+{
+    RefPtr<TracedValue> json = TracedValue::create();
+    for (ClassAgeCountsMap::const_iterator it = classAgeCounts.begin(), end = classAgeCounts.end(); it != end; ++it) {
+        json->beginArray(it->key.ascii().data());
+        for (size_t age = 0; age <= maxHeapObjectAge; ++age)
+            json->pushInteger(it->value.ages[age]);
+        json->endArray();
+    }
+    TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
+}
 #endif
 
 } // namespace blink