bpo-36103: change default buffer size of shutil.copyfileobj()#12115
Merged
Conversation
It is changed from 16KiB to 64KiB. The previous default value is used since 1990. coreutils chose 128 KiB as minimum buffer size for block device I/O. But shutil.copyfileobj() can be used for non block devices. So I choose more conservative value. As my quick benchmark, performance difference between 64KiB and 128 KiB is up to ~5%. On the other hand, performance difference between 32 KiB and 64 KiB can be more than 10% when file is fully buffered. This is why 64 KiB is rational value.
methane
changed the title
|
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
It is changed from 16KiB to 64KiB. The previous default value
is used since 1990.
coreutils chose 128 KiB as minimum buffer size for block device I/O.
But shutil.copyfileobj() can be used for non block devices.
So I choose more conservative value.
As my quick benchmark, performance difference between 64KiB and
128 KiB is up to ~5%. On the other hand, performance difference
between 32 KiB and 64 KiB can be more than 10% when file is fully
buffered.
This is why I think 64 KiB is rational value.
https://bugs.python.org/issue36103