Skip to content

[3.6] bpo-34010: Fix tarfile read performance regression (GH-8020) #8083

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
miss-islington merged 1 commit into from
Jul 4, 2018
Merged

[3.6] bpo-34010: Fix tarfile read performance regression (GH-8020) #8083

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 11 additions & 9 deletions Lib/tarfile.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -534,7 +534,7 @@ def read(self, size=None):
if not buf:
break
t.append(buf)
buf = "".join(t)
buf = b"".join(t)
else:
buf = self._read(size)
self.pos += len(buf)
Expand All @@ -547,6 +547,7 @@ def _read(self, size):
return self.__read(size)

c = len(self.dbuf)
t = [self.dbuf]
while c < size:
buf = self.__read(self.bufsize)
if not buf:
Expand All @@ -555,26 +556,27 @@ def _read(self, size):
buf = self.cmp.decompress(buf)
except self.exception:
raise ReadError("invalid compressed data")
self.dbuf += buf
t.append(buf)
c += len(buf)
buf = self.dbuf[:size]
self.dbuf = self.dbuf[size:]
return buf
t = b"".join(t)
self.dbuf = t[size:]
return t[:size]

def __read(self, size):
"""Return size bytes from stream. If internal buffer is empty,
read another block from the stream.
"""
c = len(self.buf)
t = [self.buf]
while c < size:
buf = self.fileobj.read(self.bufsize)
if not buf:
break
self.buf += buf
t.append(buf)
c += len(buf)
buf = self.buf[:size]
self.buf = self.buf[size:]
return buf
t = b"".join(t)
self.buf = t[size:]
return t[:size]
# class _Stream

class _StreamProxy(object):
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2018-07-04-07-36-53.bpo-34010.VNDkde.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fixed a performance regression for reading streams with tarfile. The
buffered read should use a list, instead of appending to a bytes object.