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https://issues.apache.org/jira/browse/ARROW-360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15793613#comment-15793613
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Wes McKinney commented on ARROW-360:
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Hm, sorta bad news:
http://stackoverflow.com/questions/9078259/realloc-alignment. We should
definitely permit shrinking the buffer, but if we want to guarantee aligned
memory, then we have to allocate-copy.
What we could do is add a {{MemoryPool::Reallocate}} virtual function with a
default implementation does does reallocate-copy, then an application which
might less strict about memory alignment can choose to use realloc instead of
{{posix_memalign}} plus {{memcpy}}.
> C++: Add method to shrink PoolBuffer using realloc
> --------------------------------------------------
>
> Key: ARROW-360
> URL: https://issues.apache.org/jira/browse/ARROW-360
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Uwe L. Korn
> Assignee: Uwe L. Korn
>
> In the case where we have optimistically allocated a large PoolBuffer, we
> could shrink it later again using a call to {{realloc}}. This should free the
> exceeding memory but avoids an actual {{memcpy}}.
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