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| author | Inada Naoki <methane@users.noreply.github.com> | 2019-03-02 04:31:01 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2019-03-02 04:31:01 (GMT) |
| commit | 4f1903061877776973c1bbfadd3d3f146920856e (patch) | |
| tree | e9ef1a128bbee617b497bedfa52c583d36b48562 /Misc | |
| parent | bcfa450f210074e16feb761ae5b3e966a2532fcf (diff) | |
| download | cpython-4f1903061877776973c1bbfadd3d3f146920856e.zip cpython-4f1903061877776973c1bbfadd3d3f146920856e.tar.gz cpython-4f1903061877776973c1bbfadd3d3f146920856e.tar.bz2 | |
bpo-36103: change default buffer size of shutil.copyfileobj() (GH-12115)
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.
Diffstat (limited to 'Misc')
| -rw-r--r-- | Misc/NEWS.d/next/Library/2019-03-01-16-10-01.bpo-36103.n6VgXL.rst | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/Misc/NEWS.d/next/Library/2019-03-01-16-10-01.bpo-36103.n6VgXL.rst b/Misc/NEWS.d/next/Library/2019-03-01-16-10-01.bpo-36103.n6VgXL.rst new file mode 100644 index 0000000..97ed658 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-03-01-16-10-01.bpo-36103.n6VgXL.rst @@ -0,0 +1,3 @@ +Default buffer size used by ``shutil.copyfileobj()`` is changed from 16 KiB +to 64 KiB on non-Windows platform to reduce system call overhead. Contributed +by INADA Naoki. |