Fix idle notification for background tab.

src/heap/gc-idle-time-handler.cc

Index: src/heap/gc-idle-time-handler.cc
diff --git a/src/heap/gc-idle-time-handler.cc b/src/heap/gc-idle-time-handler.cc
index efce981ee8c2037a60216e222384de34cf7408e8..bd8f7aeec32c2e10666d31fa52a53f0d0b36401b 100644
--- a/src/heap/gc-idle-time-handler.cc
+++ b/src/heap/gc-idle-time-handler.cc
@@ -114,6 +114,10 @@ bool GCIdleTimeHandler::ShouldDoScavenge(
     size_t idle_time_in_ms, size_t new_space_size, size_t used_new_space_size,
     size_t scavenge_speed_in_bytes_per_ms,
     size_t new_space_allocation_throughput_in_bytes_per_ms) {
+  if (idle_time_in_ms >= kMinBackgroundIdleTime) {
+    // It is better to do full GC for the background tab.
+    return false;
+  }
   size_t new_space_allocation_limit =
       kMaxScheduledIdleTime * scavenge_speed_in_bytes_per_ms;
 
@@ -193,8 +197,9 @@ bool GCIdleTimeHandler::ShouldDoOverApproximateWeakClosure(
 }
 
 
-GCIdleTimeAction GCIdleTimeHandler::NothingOrDone() {
-  if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes) {
+GCIdleTimeAction GCIdleTimeHandler::NothingOrDone(double idle_time_in_ms) {
+  if (idle_times_which_made_no_progress_ >= kMaxNoProgressIdleTimes &&
+      idle_time_in_ms < kMinBackgroundIdleTime) {
     return GCIdleTimeAction::Done();
   } else {
     idle_times_which_made_no_progress_++;

[rmcilroy, 2015/07/29 18:11:04]

Could this cause wrapping of idle_times_which_made_no_progress_? Maybe clap
idle_times_which_made_no_progress_ to be less than or equal to
kMaxNoProgressIdleTimes?

[ulan, 2015/07/29 18:21:30]

Thanks, rewrote to clap the counter.
Interval between background idle notifications is at least 1 second, so wrapping
can happen in 60 years. :)

[rmcilroy, 2015/07/30 07:14:07]

Better safe than sorry ;). Thanks.

@@ -232,7 +237,7 @@ GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
   // get the right idle signal.
   if (ShouldDoContextDisposalMarkCompact(heap_state.contexts_disposed,
                                          heap_state.contexts_disposal_rate)) {
-    return NothingOrDone();
+    return NothingOrDone(idle_time_in_ms);
   }
 
   if (ShouldDoScavenge(
@@ -247,7 +252,7 @@ GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
     if (heap_state.sweeping_completed) {
       return GCIdleTimeAction::FinalizeSweeping();
     } else {
-      return NothingOrDone();
+      return NothingOrDone(idle_time_in_ms);
     }
   }