Reduce wait times for very large PEXE files.

src/IceThreading.h

Index: src/IceThreading.h
diff --git a/src/IceThreading.h b/src/IceThreading.h
index 40ada47c1622d4780cfe7fd3b5b5f83301795910..1cdca8e764a9d1a6536f99e4955ac40b826a96c1 100644
--- a/src/IceThreading.h
+++ b/src/IceThreading.h
@@ -67,7 +67,7 @@ public:
     }
     GrewOrEnded.notify_one();
   }
-  std::unique_ptr<T> blockingPop() {
+  std::unique_ptr<T> blockingPop(size_t NotifyWhenDownToSize = MaxStaticSize) {

[Jim Stichnoth, 2016/04/13 15:33:19]

Would it make sense to also apply this to blockingPush() onto the emit queue? 
The emit thread presumably also spends a lot of its time blocked waiting for
more work items, so the translator thread spends significant time notifying and
unblocking the emit thread.

     std::unique_ptr<T> Item;
     bool ShouldNotifyProducer = false;
     {
@@ -75,7 +75,7 @@ public:
       GrewOrEnded.wait(L, [this] { return IsEnded || !empty() || Sequential; });
       if (!empty()) {
         Item = pop();
-        ShouldNotifyProducer = !IsEnded;
+        ShouldNotifyProducer = (size() < NotifyWhenDownToSize) && !IsEnded;
       }
     }
     if (ShouldNotifyProducer)