STINNER Victor <victor.stin...@haypocalc.com> added the comment:
+# A constant likely larger than the underlying OS pipe buffer size.
+# Windows limit seems to be around 512B, and most Unix kernels have a 64K pipe
+# buffer size: take 1MB to be sure.
+PIPE_MAX_SIZE = 1024 * 1024
Hum, I am not sure that the comment is correct. If I understood correctly the
usage of this constant: write PIPE_MAX_SIZE into a blocking pipe must block
because PIPE_MAX_SIZE is greater than the size of the pipe buffer. I don't know
what happen if you write PIPE_MAX_SIZE into a nonblocking pipe: the beginning
of the buffer is written and write() returns something lesser than
PIPE_MAX_SIZE?
You may specify that if you should greater or equal to os.fpathconf(fd,
"PC_PIPE_BUF").
-----------
'sys.stderr.write("xyz"*%d);'
- 'sys.stdout.write(sys.stdin.read())' % pipe_buf],
+ 'sys.stdout.write(sys.stdin.read())' %
+ support.PIPE_MAX_SIZE],
and
+ string_to_write = b"abc" * support.PIPE_MAX_SIZE
Here you use PIPE_MAX_SIZE*3, not PIPE_MAX_SIZE :-) You can use b'abc' *
(support.PIPE_MAX_SIZE // 3), or b'a' * support.PIPE_MAX_SIZE.
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue12196>
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