diff --git a/communication/src/allocator/thread.rs b/communication/src/allocator/thread.rs
index c957755c5..054804562 100644
--- a/communication/src/allocator/thread.rs
+++ b/communication/src/allocator/thread.rs
@@ -94,12 +94,12 @@ impl<T> Pull<T> for Puller<T> {
     #[inline]
     fn pull(&mut self) -> &mut Option<T> {
         let mut borrow = self.source.borrow_mut();
-        // if let Some(element) = self.current.take() {
-        //     // TODO : Arbitrary constant.
-        //     if borrow.1.len() < 16 {
-        //         borrow.1.push_back(element);
-        //     }
-        // }
+        if let Some(element) = self.current.take() {
+            // TODO : Arbitrary constant.
+            if borrow.1.len() < 16 {
+                borrow.1.push_back(element);
+            }
+        }
         self.current = borrow.0.pop_front();
         &mut self.current
     }
diff --git a/container/src/lib.rs b/container/src/lib.rs
index 9394f1ec0..0449dc9b9 100644
--- a/container/src/lib.rs
+++ b/container/src/lib.rs
@@ -165,6 +165,10 @@ impl<T, C: SizableContainer + PushInto<T>> PushInto<T> for CapacityContainerBuil
         // Maybe flush
         if self.current.at_capacity() {
             self.pending.push_back(std::mem::take(&mut self.current));
+            if let Some(spare) = self.empty.take() {
+                self.current = spare;
+                self.current.clear();
+            }
         }
     }
 }
@@ -186,9 +190,12 @@ impl<C: Container + Clone + 'static> ContainerBuilder for CapacityContainerBuild
     fn finish(&mut self) -> Option<&mut C> {
         if !self.current.is_empty() {
             self.pending.push_back(std::mem::take(&mut self.current));
+            if let Some(spare) = &mut self.empty {
+                std::mem::swap(&mut self.current, spare);
+                self.current.clear();
+            }
         }
-        self.empty = self.pending.pop_front();
-        self.empty.as_mut()
+        self.extract()
     }
 }
 
diff --git a/timely/examples/columnar.rs b/timely/examples/columnar.rs
index 12d362f3c..cd431ed98 100644
--- a/timely/examples/columnar.rs
+++ b/timely/examples/columnar.rs
@@ -99,7 +99,7 @@ fn main() {
         });
 
         // introduce data and watch!
-        for round in 0..10 {
+        for round in 0.. {
             input.send(WordCountReference { text: "flat container", diff: 1 });
             input.advance_to(round + 1);
             while probe.less_than(input.time()) {
@@ -327,9 +327,12 @@ mod builder {
         fn finish(&mut self) -> Option<&mut Self::Container> {
             if !self.current.is_empty() {
                 self.pending.push_back(Column::Typed(std::mem::take(&mut self.current)));
+                if let Some(Column::Typed(spare)) = self.empty.take() {
+                    self.current = spare;
+                    self.current.clear();
+                }
             }
-            self.empty = self.pending.pop_front();
-            self.empty.as_mut()
+            self.extract()
         }
     }