maxburke commented on code in PR #9016:
URL: https://github.com/apache/arrow-rs/pull/9016#discussion_r2635984476
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arrow-array/src/array/byte_view_array.rs:
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@@ -885,8 +896,11 @@ impl<T: ByteViewType + ?Sized> Array for
GenericByteViewArray<T> {
fn shrink_to_fit(&mut self) {
self.views.shrink_to_fit();
- self.buffers.iter_mut().for_each(|b| b.shrink_to_fit());
- self.buffers.shrink_to_fit();
+
+ if let Some(buffers) = Arc::get_mut(&mut self.buffers) {
Review Comment:
So the issue I have with `Arc::make_mut` is that if I slice array I now have
two references to the underlying buffers. If I call `shrink_to_fit` on one of
them, `Arc::make_mut` will clone the buffers and then `shrink_to_fit` will be
called on one of them. But because the underlying buffers end up being cloned,
it doesn't make the original allocation shrink and in the end it'll end up
using more memory, until the other reference is dropped.
Additionally it'll create more allocator pressure because the buffer cloning
will duplicate the buffer at it's pre-shrunken size before it's shrunk.
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