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bpo-42160: reduce overhead in tempfile #22997

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Merged
merged 9 commits into from
Oct 30, 2020
Merged

bpo-42160: reduce overhead in tempfile #22997

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f10516b
bpo-42160: reduce overhead in tempfile
Deric-W Oct 26, 2020
9a77aee
Merge branch 'master' of github.com:python/cpython into tempfile-over…
Deric-W Oct 26, 2020
a26da4f
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 27, 2020
3090bec
revert unnecessary change in _get_candidate_names
Deric-W Oct 27, 2020
3a25c07
Merge branch 'tempfile-overhead' of github.com:Deric-W/cpython into t…
Deric-W Oct 27, 2020
9e7e578
Merge branch 'master' of github.com:python/cpython into tempfile-over…
Deric-W Oct 29, 2020
faa415d
remove variants property from tempfile._RandomNameSequence
Deric-W Oct 29, 2020
395887d
replace Random.choice in tempfile._RandomNameSequence with Random.cho…
Deric-W Oct 29, 2020
dcdde39
fix typo in news entry
Deric-W Oct 29, 2020
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22 changes: 10 additions & 12 deletions Lib/tempfile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -129,24 +129,22 @@ class _RandomNameSequence:

_RandomNameSequence is an iterator."""

characters = "abcdefghijklmnopqrstuvwxyz0123456789_"

@property
def rng(self):
cur_pid = _os.getpid()
if cur_pid != getattr(self, '_rng_pid', None):
self._rng = _Random()
self._rng_pid = cur_pid
return self._rng
def __init__(self, characters="abcdefghijklmnopqrstuvwxyz0123456789_", length=8, rng=None):
if rng is None:
rng = _Random()
if hasattr(_os, "fork"):
# prevent same state after fork
_os.register_at_fork(after_in_child=rng.seed)
self.rng = rng
self.characters = characters
self.length = length

def __iter__(self):
return self

def __next__(self):
c = self.characters
choose = self.rng.choice
letters = [choose(c) for dummy in range(8)]
return ''.join(letters)
return ''.join(self.rng.choices(c, k=self.length))

def _candidate_tempdir_list():
"""Generate a list of candidate temporary directories which
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4 changes: 2 additions & 2 deletions Lib/test/test_tempfile.py
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Expand Up @@ -153,8 +153,8 @@ def setUp(self):
self.r = tempfile._RandomNameSequence()
super().setUp()

def test_get_six_char_str(self):
# _RandomNameSequence returns a six-character string
def test_get_eight_char_str(self):
# _RandomNameSequence returns a eight-character string
s = next(self.r)
self.nameCheck(s, '', '', '')

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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2020-10-27-00-42-09.bpo-42160.eiLOCi.rst
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@@ -0,0 +1 @@
Replaced pid check in ``tempfile._RandomNameSequence`` with ``os.register_at_fork`` to reduce overhead.