[jira] [Created] (ARROW-7522) Broken Record Batch returned from a function call

["Chengxin Ma (Jira)" <ji...@apache.org>]

Chengxin Ma created ARROW-7522:
----------------------------------

             Summary: Broken Record Batch returned from a function call
                 Key: ARROW-7522
                 URL: https://issues.apache.org/jira/browse/ARROW-7522
             Project: Apache Arrow
          Issue Type: Bug
          Components: C++, C++ - Plasma
    Affects Versions: 0.15.1
         Environment: macOS
            Reporter: Chengxin Ma


Scenario: retrieving Record Batch from Plasma with known Object ID.

The following code snippet works well:
{code:java}
int main(int argc, char **argv)
{
    plasma::ObjectID object_id = plasma::ObjectID::from_binary("0FF1CE00C0FFEE00BEEF");

    // Start up and connect a Plasma client.
    plasma::PlasmaClient client;
    ARROW_CHECK_OK(client.Connect("/tmp/store"));

    plasma::ObjectBuffer object_buffer;
    ARROW_CHECK_OK(client.Get(&object_id, 1, -1, &object_buffer));

    // Retrieve object data.
    auto buffer = object_buffer.data;

    arrow::io::BufferReader buffer_reader(buffer); 
    std::shared_ptr<arrow::ipc::RecordBatchReader> record_batch_stream_reader;
    ARROW_CHECK_OK(arrow::ipc::RecordBatchStreamReader::Open(&buffer_reader, &record_batch_stream_reader));

    std::shared_ptr<arrow::RecordBatch> record_batch;
    arrow::Status status = record_batch_stream_reader->ReadNext(&record_batch);

    std::cout << "record_batch->column_name(0): " << record_batch->column_name(0) << std::endl;
    std::cout << "record_batch->num_columns(): " << record_batch->num_columns() << std::endl;
    std::cout << "record_batch->num_rows(): " << record_batch->num_rows() << std::endl;
    std::cout << "record_batch->column(0)->length(): "
              << record_batch->column(0)->length() << std::endl;
    std::cout << "record_batch->column(0)->ToString(): "
              << record_batch->column(0)->ToString() << std::endl;
}
{code}
{{record_batch->column(0)->ToString()}} would incur a segmentation fault if retrieving Record Batch is wrapped in a function:
{code:java}
std::shared_ptr<arrow::RecordBatch> GetRecordBatchFromPlasma(plasma::ObjectID object_id)
{
    // Start up and connect a Plasma client.
    plasma::PlasmaClient client;
    ARROW_CHECK_OK(client.Connect("/tmp/store"));

    plasma::ObjectBuffer object_buffer;
    ARROW_CHECK_OK(client.Get(&object_id, 1, -1, &object_buffer));

    // Retrieve object data.
    auto buffer = object_buffer.data;

    arrow::io::BufferReader buffer_reader(buffer);
    std::shared_ptr<arrow::ipc::RecordBatchReader> record_batch_stream_reader;
    ARROW_CHECK_OK(arrow::ipc::RecordBatchStreamReader::Open(&buffer_reader, &record_batch_stream_reader));

    std::shared_ptr<arrow::RecordBatch> record_batch;
    arrow::Status status = record_batch_stream_reader->ReadNext(&record_batch);

    // Disconnect the client.
    ARROW_CHECK_OK(client.Disconnect());

    return record_batch;
}

int main(int argc, char **argv)
{
    plasma::ObjectID object_id = plasma::ObjectID::from_binary("0FF1CE00C0FFEE00BEEF");

    std::shared_ptr<arrow::RecordBatch> record_batch = GetRecordBatchFromPlasma(object_id);

    std::cout << "record_batch->column_name(0): " << record_batch->column_name(0) << std::endl;
    std::cout << "record_batch->num_columns(): " << record_batch->num_columns() << std::endl;
    std::cout << "record_batch->num_rows(): " << record_batch->num_rows() << std::endl;
    std::cout << "record_batch->column(0)->length(): "
              << record_batch->column(0)->length() << std::endl;
    std::cout << "record_batch->column(0)->ToString(): "
              << record_batch->column(0)->ToString() << std::endl;
}
{code}
The meta info of the Record Batch such as number of columns and rows is still available, but I can't see the content of the columns.

{{lldb}} says that the stop reason is {{EXC_BAD_ACCESS}}, so I think the Record Batch is destroyed after {{GetRecordBatchFromPlasma}} finishes. But why can I still see the meta info of this Record Batch?
 What is the proper way to get the Record Batch if we insist using a function?



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