Message137081
> +# 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.
Correct.
> 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?
>
Correct. Note that it could also fail with EAGAIN, that's why I added
an except OSError clause to the write.
> You may specify that if you should greater or equal to os.fpathconf(fd, "PC_PIPE_BUF").
>
I don't understand what you mean. It will be greater than PIPE_BUF,
which is around 4096 (I think 512 guaranteed by POSIX).
> 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.
>
I know, but that's what the original code did, so I kept it. |
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Date |
User |
Action |
Args |
2011-05-27 16:34:42 | neologix | set | recipients:
+ neologix, pitrou, vstinner |
2011-05-27 16:34:42 | neologix | link | issue12196 messages |
2011-05-27 16:34:41 | neologix | create | |
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