diff --git a/Builds/VisualStudio2015/RippleD.vcxproj b/Builds/VisualStudio2015/RippleD.vcxproj
index 4c0c2c9aa..b512202ed 100644
--- a/Builds/VisualStudio2015/RippleD.vcxproj
+++ b/Builds/VisualStudio2015/RippleD.vcxproj
@@ -1956,6 +1956,8 @@
     </ClInclude>
     <ClInclude Include="..\..\src\ripple\basics\make_SSLContext.h">
     </ClInclude>
+    <ClInclude Include="..\..\src\ripple\basics\qalloc.h">
+    </ClInclude>
     <ClInclude Include="..\..\src\ripple\basics\RangeSet.h">
     </ClInclude>
     <None Include="..\..\src\ripple\basics\README.md">
@@ -3965,8 +3967,6 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='debug|x64'">True</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='release|x64'">True</ExcludedFromBuild>
     </ClCompile>
-    <ClInclude Include="..\..\src\ripple\unl\tests\qalloc.h">
-    </ClInclude>
     <ClInclude Include="..\..\src\ripple\unl\tests\Sim1.h">
     </ClInclude>
     <ClInclude Include="..\..\src\ripple\unl\tests\Sim2.h">
diff --git a/Builds/VisualStudio2015/RippleD.vcxproj.filters b/Builds/VisualStudio2015/RippleD.vcxproj.filters
index 3680883f6..fab7841dd 100644
--- a/Builds/VisualStudio2015/RippleD.vcxproj.filters
+++ b/Builds/VisualStudio2015/RippleD.vcxproj.filters
@@ -2685,6 +2685,9 @@
     <ClInclude Include="..\..\src\ripple\basics\make_SSLContext.h">
       <Filter>ripple\basics</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\src\ripple\basics\qalloc.h">
+      <Filter>ripple\basics</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\src\ripple\basics\RangeSet.h">
       <Filter>ripple\basics</Filter>
     </ClInclude>
@@ -4593,9 +4596,6 @@
     <ClCompile Include="..\..\src\ripple\unl\tests\Network_test.cpp">
       <Filter>ripple\unl\tests</Filter>
     </ClCompile>
-    <ClInclude Include="..\..\src\ripple\unl\tests\qalloc.h">
-      <Filter>ripple\unl\tests</Filter>
-    </ClInclude>
     <ClInclude Include="..\..\src\ripple\unl\tests\Sim1.h">
       <Filter>ripple\unl\tests</Filter>
     </ClInclude>
diff --git a/src/ripple/unl/tests/qalloc.h b/src/ripple/basics/qalloc.h
similarity index 77%
rename from src/ripple/unl/tests/qalloc.h
rename to src/ripple/basics/qalloc.h
index 29efe0ec5..bb2be4498 100644
--- a/src/ripple/unl/tests/qalloc.h
+++ b/src/ripple/basics/qalloc.h
@@ -17,8 +17,8 @@
 */
 //==============================================================================
 
-#ifndef RIPPLE_SIM_QALLOC_H_INCLUDED
-#define RIPPLE_SIM_QALLOC_H_INCLUDED
+#ifndef RIPPLE_BASICS_QALLOC_H_INCLUDED
+#define RIPPLE_BASICS_QALLOC_H_INCLUDED
 
 #include <ripple/basics/contract.h>
 #include <boost/intrusive/list.hpp>
@@ -29,9 +29,9 @@
 #include <memory>
 #include <new>
 #include <sstream>
+#include <type_traits>
 
 namespace ripple {
-namespace test {
 
 namespace detail {
 
@@ -87,11 +87,11 @@ public:
 
 } // detail
 
-template <class T>
+template <class T, bool ShareOnCopy = true>
 class qalloc_type
 {
 private:
-    template <class U>
+    template <class, bool>
     friend class qalloc_type;
 
     std::shared_ptr<
@@ -105,22 +105,24 @@ public:
         std::add_lvalue_reference<T>::type;
     using const_reference = typename
         std::add_lvalue_reference<T const>::type;
+    using propagate_on_container_move_assignment =
+        std::true_type;
 
     template <class U>
     struct rebind
     {
-        using other = qalloc_type<U>;
+        using other = qalloc_type<U, ShareOnCopy>;
     };
 
     qalloc_type (qalloc_type const&) = default;
-    qalloc_type& operator= (qalloc_type const&) = default;
     qalloc_type (qalloc_type&& other) = default;
+    qalloc_type& operator= (qalloc_type const&) = default;
     qalloc_type& operator= (qalloc_type&&) = default;
 
     qalloc_type();
 
     template <class U>
-    qalloc_type (qalloc_type<U> const& u);
+    qalloc_type (qalloc_type<U, ShareOnCopy> const& u);
 
     template <class U>
     U*
@@ -136,16 +138,23 @@ public:
     void
     deallocate (T* p, std::size_t n);
 
-    void
-    destroy (T* t);
+    template <class U>
+    bool
+    operator== (qalloc_type<U, ShareOnCopy> const& u);
 
     template <class U>
     bool
-    operator== (qalloc_type<U> const& u);
+    operator!= (qalloc_type<U, ShareOnCopy> const& u);
 
-    template <class U>
-    bool
-    operator!= (qalloc_type<U> const& u);
+    qalloc_type
+    select_on_container_copy_construction() const;
+
+private:
+    qalloc_type
+    select_on_copy(std::true_type) const;
+
+    qalloc_type
+    select_on_copy(std::false_type) const;
 };
 
 /** Allocator optimized for delete in temporal order.
@@ -158,7 +167,7 @@ public:
 
         May not be called concurrently.
 */
-using qalloc = qalloc_type<int>;
+using qalloc = qalloc_type<int, true>;
 
 //------------------------------------------------------------------------------
 
@@ -292,25 +301,25 @@ qalloc_impl<_>::deallocate (void* p)
 
 //------------------------------------------------------------------------------
 
-template <class T>
-qalloc_type<T>::qalloc_type()
+template <class T, bool ShareOnCopy>
+qalloc_type<T, ShareOnCopy>::qalloc_type()
     : impl_ (std::make_shared<
         detail::qalloc_impl<>>())
 {
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 template <class U>
-qalloc_type<T>::qalloc_type(
-        qalloc_type<U> const& u)
+qalloc_type<T, ShareOnCopy>::qalloc_type(
+        qalloc_type<U, ShareOnCopy> const& u)
     : impl_ (u.impl_)
 {
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 template <class U>
 U*
-qalloc_type<T>::alloc (std::size_t n)
+qalloc_type<T, ShareOnCopy>::alloc (std::size_t n)
 {
     if (n > std::numeric_limits<
             std::size_t>::max() / sizeof(U))
@@ -321,61 +330,77 @@ qalloc_type<T>::alloc (std::size_t n)
             std::alignment_of<U>::value));
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 template <class U>
 inline
 void
-qalloc_type<T>::dealloc(
+qalloc_type<T, ShareOnCopy>::dealloc(
     U* p, std::size_t n)
 {
     impl_->deallocate(p);
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 T*
-qalloc_type<T>::allocate (std::size_t n)
+qalloc_type<T, ShareOnCopy>::allocate (std::size_t n)
 {
     return alloc<T>(n);
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 inline
 void
-qalloc_type<T>::deallocate(
+qalloc_type<T, ShareOnCopy>::deallocate(
     T* p, std::size_t n)
 {
     dealloc(p, n);
 }
 
-template <class T>
-inline
-void
-qalloc_type<T>::destroy (T* t)
-{
-    t->~T();
-}
-
-template <class T>
+template <class T, bool ShareOnCopy>
 template <class U>
 inline
 bool
-qalloc_type<T>::operator==(
-    qalloc_type<U> const& u)
+qalloc_type<T, ShareOnCopy>::operator==(
+    qalloc_type<U, ShareOnCopy> const& u)
 {
     return impl_.get() == u.impl_.get();
 }
 
-template <class T>
+template <class T, bool ShareOnCopy>
 template <class U>
 inline
 bool
-qalloc_type<T>::operator!=(
-    qalloc_type<U> const& u)
+qalloc_type<T, ShareOnCopy>::operator!=(
+    qalloc_type<U, ShareOnCopy> const& u)
 {
     return ! (*this == u);
 }
 
-} // test
+template <class T, bool ShareOnCopy>
+auto
+qalloc_type<T, ShareOnCopy>::select_on_container_copy_construction() const ->
+    qalloc_type
+{
+    return select_on_copy(
+        std::integral_constant<bool, ShareOnCopy>{});
+}
+
+template <class T, bool ShareOnCopy>
+auto
+qalloc_type<T, ShareOnCopy>::select_on_copy(std::true_type) const ->
+    qalloc_type
+{
+    return *this; // shared arena
+}
+
+template <class T, bool ShareOnCopy>
+auto
+qalloc_type<T, ShareOnCopy>::select_on_copy(std::false_type) const ->
+    qalloc_type
+{
+    return {}; // new arena
+}
+
 } // ripple
 
 #endif
diff --git a/src/ripple/ledger/OpenView.h b/src/ripple/ledger/OpenView.h
index 4865a3820..ce9f4fc3a 100644
--- a/src/ripple/ledger/OpenView.h
+++ b/src/ripple/ledger/OpenView.h
@@ -23,7 +23,10 @@
 #include <ripple/ledger/RawView.h>
 #include <ripple/ledger/ReadView.h>
 #include <ripple/ledger/detail/RawStateTable.h>
+#include <ripple/basics/qalloc.h>
 #include <ripple/protocol/XRPAmount.h>
+#include <functional>
+#include <utility>
 
 namespace ripple {
 
@@ -51,9 +54,11 @@ private:
 
     // List of tx, key order
     using txs_map = std::map<key_type,
-        std::pair<std::shared_ptr<
-            Serializer const>, std::shared_ptr<
-                Serializer const>>>;
+        std::pair<std::shared_ptr<Serializer const>,
+        std::shared_ptr<Serializer const>>,
+        std::less<key_type>, qalloc_type<std::pair<key_type const,
+        std::pair<std::shared_ptr<Serializer const>,
+        std::shared_ptr<Serializer const>>>, false>>;
 
     Rules rules_;
     txs_map txs_;
diff --git a/src/ripple/ledger/detail/RawStateTable.h b/src/ripple/ledger/detail/RawStateTable.h
index 973e19e25..651b6b60c 100644
--- a/src/ripple/ledger/detail/RawStateTable.h
+++ b/src/ripple/ledger/detail/RawStateTable.h
@@ -22,6 +22,7 @@
 
 #include <ripple/ledger/RawView.h>
 #include <ripple/ledger/ReadView.h>
+#include <ripple/basics/qalloc.h>
 #include <map>
 #include <utility>
 
@@ -89,7 +90,9 @@ private:
     class sles_iter_impl;
 
     using items_t = std::map<key_type,
-        std::pair<Action, std::shared_ptr<SLE>>>;
+        std::pair<Action, std::shared_ptr<SLE>>,
+        std::less<key_type>, qalloc_type<std::pair<key_type const,
+        std::pair<Action, std::shared_ptr<SLE>>>, false>>;
 
     items_t items_;
     XRPAmount dropsDestroyed_ = 0;
diff --git a/src/ripple/unl/tests/BasicNetwork.h b/src/ripple/unl/tests/BasicNetwork.h
index 0bc004da9..8095f859d 100644
--- a/src/ripple/unl/tests/BasicNetwork.h
+++ b/src/ripple/unl/tests/BasicNetwork.h
@@ -20,7 +20,7 @@
 #ifndef RIPPLE_SIM_BASICNETWORK_H_INCLUDED
 #define RIPPLE_SIM_BASICNETWORK_H_INCLUDED
 
-#include <ripple/unl/tests/qalloc.h>
+#include <ripple/basics/qalloc.h>
 #include <beast/chrono/manual_clock.h>
 #include <beast/hash/hash_append.h>
 #include <beast/hash/uhash.h>
@@ -49,7 +49,7 @@ namespace test {
     vertices and configurable connections representing edges.
     The caller is responsible for creating the Peer objects ahead
     of time.
-   
+
     Peer objects cannot be destroyed once the BasicNetwork is
     constructed. To handle peers going online and offline,
     callers can simply disconnect all links and reconnect them
@@ -166,7 +166,7 @@ private:
             , h_ (std::move(h))
         {
         }
-        
+
         msg_impl (Peer* from_, Peer* to_,
                 time_point when_, Handler const& h)
             : msg (from_, to_, when_)
@@ -320,7 +320,7 @@ public:
 
             If a connection is present, both ends are
             disconnected.
-            
+
             Any pending messages on the connection
             are discarded.
 
@@ -345,7 +345,7 @@ public:
 
         Effects:
 
-            If the link is not broken when the 
+            If the link is not broken when the
             link's `delay` time has elapsed,
             the function will be invoked with
             no arguments.
@@ -399,7 +399,7 @@ public:
     cancel (cancel_token const& token);
 
     /** Perform breadth-first search.
-        
+
         Function will be called with this signature:
 
             void(std::size_t, Peer&);