Low memory page navigation GC for low end devices

third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp

Index: third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp b/third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp
index deca64c5ee5773498a32c574de0a5dbd4732bfce..7b5fc96c95624522346826ad9ad42c131eb375da 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/V8GCForContextDispose.cpp
@@ -30,12 +30,26 @@
 
 #include "bindings/core/v8/V8GCForContextDispose.h"
 
+#include "platform/Histogram.h"
+#include "platform/MemoryCoordinator.h"
 #include "platform/bindings/V8PerIsolateData.h"
 #include "platform/wtf/CurrentTime.h"
+#include "platform/wtf/ProcessMetrics.h"
 #include "platform/wtf/StdLibExtras.h"
 #include "public/platform/Platform.h"
 #include "v8/include/v8.h"
 
+size_t GetMemoryUsage() {
+  size_t usage = WTF::GetMallocUsage() + WTF::Partitions::TotalActiveBytes() +
+                 blink::ProcessHeap::TotalAllocatedObjectSize() +
+                 blink::ProcessHeap::TotalMarkedObjectSize();
+  v8::HeapStatistics v8_heap_statistics;
+  blink::V8PerIsolateData::MainThreadIsolate()->GetHeapStatistics(
+      &v8_heap_statistics);
+  usage = v8_heap_statistics.total_heap_size();
+  return usage;
+}
+
 namespace blink {
 
 V8GCForContextDispose::V8GCForContextDispose()
@@ -43,9 +57,29 @@ V8GCForContextDispose::V8GCForContextDispose()
   Reset();
 }
 
-void V8GCForContextDispose::NotifyContextDisposed(bool is_main_frame) {
+void V8GCForContextDispose::NotifyContextDisposed(
+    bool is_main_frame,
+    WindowProxy::FrameReuseStatus frame_reuse_status) {
   did_dispose_context_for_main_frame_ = is_main_frame;
   last_context_disposal_time_ = WTF::CurrentTime();
+#if OS(ANDROID)
+  // When a low end device is in a low memory situation we should prioritize
+  // memory use and trigger a V8+Blink GC. However, on Android, if the frame
+  // will not be reused, the process will likely to be killed soon so skip this.
+  if (is_main_frame && frame_reuse_status == WindowProxy::kFrameWillBeReused &&
+      MemoryCoordinator::IsLowEndDevice() &&
+      MemoryCoordinator::IsCurrentlyLowMemory()) {
+    size_t pre_gc_memory_usage = GetMemoryUsage();
+    V8PerIsolateData::MainThreadIsolate()->MemoryPressureNotification(
+        v8::MemoryPressureLevel::kCritical);
+    size_t post_gc_memory_usage = GetMemoryUsage();
+    int reduction = static_cast<int>(pre_gc_memory_usage) -
+                    static_cast<int>(post_gc_memory_usage);
+    DEFINE_STATIC_LOCAL(CustomCountHistogram, reduction_histogram,
+                        ("LowMemoryPageNavigationGC.Reduction", 0, 512, 50));

[Ilya Sherman, 2017/06/26 18:48:37]

nit: 0 is not a valid histogram min; please use 1 instead.  (Also, I believe
there's a DCHECK enforcing this, so please double-check that you're building
with DCHECKs enabled.)

[keishi, 2017/06/27 03:44:53]

Done.

FYI looks like we don't have a DCHECK yet
https://cs.chromium.org/chromium/src/base/metrics/histogram.cc?rcl=942e74b0d7...
. We have many places where min=0.

[Ilya Sherman, 2017/06/27 03:48:44]

Ah, I guess I misremembered.  Thanks for pointing that out!

+    reduction_histogram.Count(reduction / 1024 / 1024);
+  }
+#endif
   V8PerIsolateData::MainThreadIsolate()->ContextDisposedNotification(
       !is_main_frame);
   pseudo_idle_timer_.Stop();