From 9bd522d7d13b8db51a87e650c5b439ccf49c616c Mon Sep 17 00:00:00 2001 From: Barry Warsaw Date: Fri, 13 Apr 2007 16:12:02 +0000 Subject: Add code to read from master_fd in the parent, breaking when we get an OSError (EIO can occur on Linux) or there's no more data to read. Without this, test_pty.py can hang on the waitpid() because the child is blocking on the stdout write. This will definitely happen on Mac OS X and could potentially happen on other platforms. See the comment for details. --- Lib/test/test_pty.py | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/Lib/test/test_pty.py b/Lib/test/test_pty.py index 02290be..e69d7ea 100644 --- a/Lib/test/test_pty.py +++ b/Lib/test/test_pty.py @@ -115,6 +115,24 @@ if pid == pty.CHILD: os._exit(4) else: debug("Waiting for child (%d) to finish."%pid) + # In verbose mode, we have to consume the debug output from the child or + # the child will block, causing this test to hang in the parent's + # waitpid() call. The child blocks after a platform-dependent amount of + # data is written to its fd. On Linux 2.6, it's 4000 bytes and the child + # won't block, but on OS X even the small writes in the child above will + # block it. Also on Linux, the read() will throw an OSError (input/output + # error) when it tries to read past the end of the buffer but the child's + # already exited, so catch and discard those exceptions. It's not worth + # checking for EIO. + while True: + try: + data = os.read(master_fd, 80) + except OSError: + break + if not data: + break + sys.stdout.write(data.replace('\r\n', '\n')) + ##line = os.read(master_fd, 80) ##lines = line.replace('\r\n', '\n').split('\n') ##if False and lines != ['In child, calling os.setsid()', -- cgit v0.12