Created by: zhiqiu

PR types

Bug fixes

PR changes

APIs

Describe

Temporally disable zero_copy of to_variable and to_tensor

Why?

we found two problems when enable zero_copy on CPUPlace.

• Eigen requires 16-bytes alignments, but the data of numpy array may not always satisfy the condition. Details: https://eigen.tuxfamily.org/dox/group__TopicUnalignedArrayAssert.html
• When used in flask framework, it may result in hang. Details: https://github.com/PaddlePaddle/Paddle/issues/26635
• zero_copy is only used in CPUPlace. For training on CPU, the computation is not as fast as on GPU, so the time consumption of doing copy may not be the major issue of performance.

So, we temporally diable the zero_copy strategy.