Estimate number of cells needed in the hashmap.

2 files changed, 3 insertions, 2 deletions

diff --git a/eval/src/vespa/eval/tensor/sparse/sparse_tensor_apply.hpp b/eval/src/vespa/eval/tensor/sparse/sparse_tensor_apply.hpp
index ea3e2dae09b..0b9e127dd82 100644
--- a/eval/src/vespa/eval/tensor/sparse/sparse_tensor_apply.hpp
+++ b/eval/src/vespa/eval/tensor/sparse/sparse_tensor_apply.hpp
@@ -15,10 +15,10 @@ apply(const SparseTensor &lhs, const SparseTensor &rhs, Function &&func)
 {
     DirectTensorBuilder<SparseTensor> builder(lhs.combineDimensionsWith(rhs));
     TensorAddressCombiner addressCombiner(lhs.fast_type(), rhs.fast_type());
+    builder.reserve((lhs.cells().size() * rhs.cells())*2);
     for (const auto &lhsCell : lhs.cells()) {
         for (const auto &rhsCell : rhs.cells()) {
-            bool combineSuccess = addressCombiner.combine(lhsCell.first,
-                                                          rhsCell.first);
+            bool combineSuccess = addressCombiner.combine(lhsCell.first, rhsCell.first);
             if (combineSuccess) {
                 builder.insertCell(addressCombiner.getAddressRef(),
                                    func(lhsCell.second, rhsCell.second));
diff --git a/eval/src/vespa/eval/tensor/sparse/sparse_tensor_reduce.hpp b/eval/src/vespa/eval/tensor/sparse/sparse_tensor_reduce.hpp
index 174e4c5237c..8a43c6b52bd 100644
--- a/eval/src/vespa/eval/tensor/sparse/sparse_tensor_reduce.hpp
+++ b/eval/src/vespa/eval/tensor/sparse/sparse_tensor_reduce.hpp
@@ -48,6 +48,7 @@ reduce(const SparseTensor &tensor,
         return reduceAll(tensor, builder, func);
     }
     TensorAddressReducer addressReducer(tensor.fast_type(), dimensions);
+    builder.reserve(tensor.cells().size()*2);
     for (const auto &cell : tensor.cells()) {
         addressReducer.reduce(cell.first);
         builder.insertCell(addressReducer.getAddressRef(), cell.second, func);