diff --git a/src/db/db/dbOriginalLayerEdgePairs.cc b/src/db/db/dbOriginalLayerEdgePairs.cc
index cf9b99c27..3544512fe 100644
--- a/src/db/db/dbOriginalLayerEdgePairs.cc
+++ b/src/db/db/dbOriginalLayerEdgePairs.cc
@@ -181,7 +181,7 @@ OriginalLayerEdgePairs::begin_iter () const
 bool
 OriginalLayerEdgePairs::empty () const
 {
-  return m_iter.at_end ();
+  return m_iter.at_end_no_lock ();
 }
 
 const db::EdgePair *
diff --git a/src/db/db/dbOriginalLayerEdges.cc b/src/db/db/dbOriginalLayerEdges.cc
index 1cb19d028..da181c17d 100644
--- a/src/db/db/dbOriginalLayerEdges.cc
+++ b/src/db/db/dbOriginalLayerEdges.cc
@@ -218,7 +218,7 @@ OriginalLayerEdges::begin_merged_iter () const
 bool
 OriginalLayerEdges::empty () const
 {
-  return m_iter.at_end ();
+  return m_iter.at_end_no_lock ();
 }
 
 bool
diff --git a/src/db/db/dbOriginalLayerRegion.cc b/src/db/db/dbOriginalLayerRegion.cc
index d089f4001..d5ba1cf13 100644
--- a/src/db/db/dbOriginalLayerRegion.cc
+++ b/src/db/db/dbOriginalLayerRegion.cc
@@ -330,11 +330,7 @@ OriginalLayerRegion::begin_merged_iter () const
 bool
 OriginalLayerRegion::empty () const
 {
-  //  NOTE: we should to make sure the iterator isn't validated as this would spoil the usability or OriginalLayerRegion upon
-  //  layout changes
-  db::RecursiveShapeIterator iter = m_iter;
-
-  return iter.at_end ();
+  return m_iter.at_end_no_lock ();
 }
 
 bool
diff --git a/src/db/db/dbOriginalLayerTexts.cc b/src/db/db/dbOriginalLayerTexts.cc
index 6555eb4dc..9d8622f43 100644
--- a/src/db/db/dbOriginalLayerTexts.cc
+++ b/src/db/db/dbOriginalLayerTexts.cc
@@ -181,7 +181,7 @@ OriginalLayerTexts::begin_iter () const
 bool
 OriginalLayerTexts::empty () const
 {
-  return m_iter.at_end ();
+  return m_iter.at_end_no_lock ();
 }
 
 const db::Text *
diff --git a/src/db/db/dbRecursiveShapeIterator.cc b/src/db/db/dbRecursiveShapeIterator.cc
index fda051d39..c92cd4bc4 100644
--- a/src/db/db/dbRecursiveShapeIterator.cc
+++ b/src/db/db/dbRecursiveShapeIterator.cc
@@ -598,6 +598,13 @@ RecursiveShapeIterator::at_end () const
   return m_shape.at_end () || is_inactive ();
 }
 
+bool
+RecursiveShapeIterator::at_end_no_lock () const
+{
+  RecursiveShapeIterator copy (*this);
+  return copy.at_end ();
+}
+
 std::vector<db::InstElement>
 RecursiveShapeIterator::path () const
 {
diff --git a/src/db/db/dbRecursiveShapeIterator.h b/src/db/db/dbRecursiveShapeIterator.h
index ae337a29e..26ee32b7e 100644
--- a/src/db/db/dbRecursiveShapeIterator.h
+++ b/src/db/db/dbRecursiveShapeIterator.h
@@ -709,6 +709,16 @@ public:
    */
   bool at_end () const;
 
+  /**
+   *  @brief End of iterator predicate
+   *
+   *  Returns true, if the iterator is at the end of the sequence
+   *
+   *  This version does not lock the layout and can be used after initialization
+   *  to detect empty sequences.
+   */
+  bool at_end_no_lock () const;
+
   /**
    *  @brief Gets the translated property ID
    *
diff --git a/src/db/db/dbTilingProcessor.cc b/src/db/db/dbTilingProcessor.cc
index b25ce543a..131c3bb4f 100644
--- a/src/db/db/dbTilingProcessor.cc
+++ b/src/db/db/dbTilingProcessor.cc
@@ -876,7 +876,7 @@ TilingProcessor::execute (const std::string &desc)
 
   if (tot_box.empty ()) {
     for (std::vector<InputSpec>::const_iterator i = m_inputs.begin (); i != m_inputs.end (); ++i) {
-      if (! i->iter.at_end ()) {
+      if (! i->iter.at_end_no_lock ()) {
         if (scale_to_dbu ()) {
           double dbu_value = i->iter.layout () ? i->iter.layout ()->dbu () : dbu ();
           tot_box += i->iter.bbox ().transformed (db::CplxTrans (dbu_value) * db::CplxTrans (i->trans));
diff --git a/src/db/unit_tests/dbTilingProcessorTests.cc b/src/db/unit_tests/dbTilingProcessorTests.cc
index e31a885e5..18a741fce 100644
--- a/src/db/unit_tests/dbTilingProcessorTests.cc
+++ b/src/db/unit_tests/dbTilingProcessorTests.cc
@@ -148,7 +148,9 @@ TEST(2)
     tp.queue ("_output(o1, _tile ? (i1 & i2 & _tile) : (i1 & i2), false)");
     tp.queue ("!_tile && _output(o2, i1.outside(i2), false)");
     tp.queue ("_tile && _output(o3, _tile, false)");
+    EXPECT_EQ (ly.under_construction (), false);
     tp.execute ("test");
+    EXPECT_EQ (ly.under_construction (), false);
 
     EXPECT_EQ (to_s (ly, top, o1), "box (60,10;70,20);box (10,10;30,30)");
     EXPECT_EQ (to_s (ly, top, o2), "box (50,40;80,70)");
diff --git a/src/drc/drc/built-in-macros/_drc_layer.rb b/src/drc/drc/built-in-macros/_drc_layer.rb
index c384d82c6..25f47c22d 100644
--- a/src/drc/drc/built-in-macros/_drc_layer.rb
+++ b/src/drc/drc/built-in-macros/_drc_layer.rb
@@ -4624,6 +4624,8 @@ TP_SCRIPT
         res
       end
 
+      tp._destroy
+
       DRCLayer::new(@engine, res)
 
     end