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https://issues.apache.org/jira/browse/ARROW-1973?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16357411#comment-16357411
 ] 

ASF GitHub Bot commented on ARROW-1973:
---------------------------------------

cpcloud commented on a change in pull request #1578: ARROW-1973: [Python] 
Memory leak when converting Arrow tables with array columns to Pandas 
dataframes.
URL: https://github.com/apache/arrow/pull/1578#discussion_r167034173
 
 

 ##########
 File path: cpp/src/arrow/python/arrow_to_pandas.cc
 ##########
 @@ -502,18 +502,20 @@ template <typename ArrowType>
 inline Status ConvertListsLike(PandasOptions options, const 
std::shared_ptr<Column>& col,
                                PyObject** out_values) {
   const ChunkedArray& data = *col->data().get();
-  auto list_type = std::static_pointer_cast<ListType>(col->type());
+  const auto& list_type = static_cast<const ListType&>(*col->type());
 
   // Get column of underlying value arrays
   std::vector<std::shared_ptr<Array>> value_arrays;
   for (int c = 0; c < data.num_chunks(); c++) {
-    auto arr = std::static_pointer_cast<ListArray>(data.chunk(c));
-    value_arrays.emplace_back(arr->values());
+    const auto& arr = static_cast<const ListArray&>(*data.chunk(c));
+    value_arrays.emplace_back(arr.values());
   }
-  auto flat_column = std::make_shared<Column>(list_type->value_field(), 
value_arrays);
+  auto flat_column = std::make_shared<Column>(list_type.value_field(), 
value_arrays);
   // TODO(ARROW-489): Currently we don't have a Python reference for single 
columns.
   //    Storing a reference to the whole Array would be to expensive.
-  PyObject* numpy_array;
+  OwnedRef owned_numpy_array;
 
 Review comment:
   Yep, thank you.

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> [Python] Memory leak when converting Arrow tables with array columns to 
> Pandas dataframes.
> ------------------------------------------------------------------------------------------
>
>                 Key: ARROW-1973
>                 URL: https://issues.apache.org/jira/browse/ARROW-1973
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++, Python
>    Affects Versions: 0.8.0
>         Environment: Linux Mint 18.2
> Anaconda Python distribution + pyarrow installed from the conda-forge channel
>            Reporter: Alexey Strokach
>            Assignee: Phillip Cloud
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 0.9.0
>
>
> There appears to be a memory leak when using PyArrow to convert tables 
> containing array columns to Pandas DataFrames.
>  See the `test_memory_leak.py` example here: 
> https://gitlab.com/ostrokach/pyarrow_duplicate_column_errors



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