Strange intermittent EIO error when writing to stdout since v3.8.0
From: Markus Trippelsdorf
Date: Thu Jun 06 2013 - 07:54:24 EST
Since v3.8.0 several people reported intermittent IO errors that happen
during high system load while using "emerge" under Gentoo:
...
File "/usr/lib64/portage/pym/portage/util/_eventloop/EventLoop.py", line 260, in iteration
if not x.callback(f, event, *x.args):
File "/usr/lib64/portage/pym/portage/util/_async/PipeLogger.py", line 99, in _output_handler
stdout_buf[os.write(stdout_fd, stdout_buf):]
File "/usr/lib64/portage/pym/portage/__init__.py", line 246, in __call__
rval = self._func(*wrapped_args, **wrapped_kwargs)
OSError: [Errno 5] Input/output error
Basically 'emerge' just writes the build output to stdout in a loop:
...
def _output_handler(self, fd, event):
background = self.background
stdout_fd = self.stdout_fd
log_file = self._log_file
while True:
buf = self._read_buf(fd, event)
if buf is None:
# not a POLLIN event, EAGAIN, etc...
break
if not buf:
# EOF
self._unregister()
self.wait()
break
else:
if not background and stdout_fd is not None:
failures = 0
stdout_buf = buf
while stdout_buf:
try:
stdout_buf = \
stdout_buf[os.write(stdout_fd, stdout_buf):]
except OSError as e:
if e.errno != errno.EAGAIN:
raise
...
see: https://bugs.gentoo.org/show_bug.cgi?id=459674
(A similar issue also happens when building Firefox since v3.8.0. But
because Firefox's build process doesn't raise an exception it just dies
at random points without giving a clue.)
Now the question is: Could this be a kernel bug? Maybe in the TTY layer?
Unfortunately the issue is not easily reproducible and a git-bisect is
out of the question.
--
Markus
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