8000 gh-121313: Limit the reading size from pipes to their default buffer size on Unix systems by aplaikner · Pull Request #121315 · python/cpython · GitHub
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gh-121313: Limit the reading size from pipes to their default buffer size on Unix systems #121315

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Merged
merged 19 commits into from
Aug 31, 2024
Merged

gh-121313: Limit the reading size from pipes to their default buffer size on Unix systems #121315

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108e65b
Add clean code
aplaikner Jul 3, 2024
37ca606
Fix linting error & sysconf unsupported error
aplaikner Jul 3, 2024
df4f307
Merge branch 'main' into feature-smaller-pipe-buffer-pull-request
aplaikner Jul 3, 2024
89936c2
📜🤖 Added by blurb_it.
blurb-it[bot] Jul 3, 2024
31c65b4
Fix news
aplaikner Jul 3, 2024
0a4e4a3
Make page size non static
aplaikner Jul 3, 2024
7afde51
Merge branch 'main' into feature-smaller-pipe-buffer-pull-request
aplaikner Jul 3, 2024
8d9b16e
Merge branch 'main' into feature-smaller-pipe-buffer-pull-request
aplaikner Jul 3, 2024
e6c64fe
Remove redundant call to pymin
aplaikner Jul 4, 2024
936b601
Shift pipe check to connection.py _recv
aplaikner Jul 5, 2024
49d8adb
Make pipe size dependant on systems page size
aplaikner Jul 5, 2024
43e19dd
Only execute fstat in case reading size is bigger than default pipe size
aplaikner Jul 5, 2024
b0b86e5
Update news message
aplaikner Jul 7, 2024
2b6ff24
Make imports order alphabetical
aplaikner Jul 7, 2024
e726f51
Shift calculation for pipe size to existing if _winapi check
aplaikner Jul 7, 2024
59cff4d
Fix linting error
aplaikner Jul 7, 2024
da10f8e
Merge branch 'main' into feature-smaller-pipe-buffer-pull-request
aplaikner Jul 7, 2024
94d4c4a
Create constant for default number of pages per pipe
8000 aplaikner Jul 7, 2024
52606d1
Merge branch 'main' into feature-smaller-pipe-buffer-pull-request
aplaikner Jul 29, 2024
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21 changes: 18 additions & 3 deletions Lib/multiprocessing/connection.py
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92D6
Original file line number Diff line number Diff line change
Expand Up @@ -11,13 +11,14 @@

import errno
import io
import itertools
import os
import stat
import sys
import socket
import struct
import time
import tempfile
import itertools
import time


from . import util
Expand Down Expand Up @@ -360,6 +361,11 @@ def _get_more_data(self, ov, maxsize):
f.write(ov.getbuffer())
return f

"""
The default size of a pipe on Linux systems is 16 times the base page size:
https://man7.org/linux/man-pages/man7/pipe.7.html
"""
PAGES_PER_PIPE = 16

class Connection(_ConnectionBase):
"""
Expand All @@ -372,11 +378,14 @@ def _close(self, _close=_multiprocessing.closesocket):
_close(self._handle)
_write = _multiprocessing.send
_read = _multiprocessing.recv
_default_pipe_size = 0
else:
def _close(self, _close=os.close):
_close(self._handle)
_write = os.write
_read = os.read
_base_page_size = os.sysconf(os.sysconf_names['SC_PAGESIZE'])
_default_pipe_size = _base_page_size * PAGES_PER_PIPE

def _send(self, buf, write=_write):
remaining = len(buf)
Expand All @@ -391,8 +400,14 @@ def _recv(self, size, read=_read):
buf = io.BytesIO()
handle = self._handle
remaining = size
is_pipe = False
if size > self._default_pipe_size > 0:
mode = os.fstat(handle).st_mode
is_pipe = stat.S_ISFIFO(mode)
limit = self._default_pipe_size if is_pipe else remaining
while remaining > 0:
chunk = read(handle, remaining)
to_read = min(limit, remaining)
chunk = read(handle, to_read)
n = len(chunk)
if n == 0:
if remaining == size:
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/C API/2024-07-03-10-11-53.gh-issue-121313.D7gARW.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Limit reading size in multiprocessing connection._recv for pipes to default pipe size of 16 times base page size, in order to avoid memory overallocation and unnecessary memory management system calls.
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