2013/7/5 Cameron Simpson <c...@zip.com.au>: > You might want to make clear that the "blocking" parameter refers > only to the file creation calls (eg socket.socket) and not to the > file descriptor itself, and is not to be confused with the UNIX > O_NONBLOCK file descriptor flag (and whatever equivalent flag may > apply on Windows).
The two following codes are the same: s = socket.socket(..., blocking=False) and s = socket.socket(...) s.setblocking(False) Both set O_NONBLOCK flag (UNIX) or clear HANDLE_FLAG_INHERIT (Windows) on the socket (which is a file descriptor). socket.socket(..., blocking=False) cannot fail with EAGAIN or EWOULDBLOCK (at least on Linux according to the manual page). > This is deducable from your PEP, but I was at first confused, and > initially expected get_blocking/set_blocking functions in New > Functions. socket objects already have get_blocking() and set_blocking() methods. If we supported the blocking flag on any file descriptor, it would make sense to add such function to the os module. But I explained in the "Add blocking parameter for file descriptors and Windows overlapped I/O" section why I only want to set/clear the blocking file on sockets. > I would expect Popen and friends to need to both clear the flag to > get the descriptors across the fork() call, and _possibly_ to set > the flag again after the fork. Naively, I would expect the the flag > to be as it was before the Popen call, after the call. As explained in the "Inheritance of file descriptors" section, the close-on-exec flag has no effect on fork: "The flag has no effect on fork(), all file descriptors are inherited by the child process." The close-on-exec flag is cleared after the fork and before the exec(). Pseudo-code for Popen: pid = os.fork() if pid: return pid # child process for fd in pass_fds: os.set_cloexec(fd, False) os.execv(...) Victor _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
