view .arcconfig @ 45035:3862de62d5cf

chg: suppress OSError in _restoreio() and add some logging (issue6330)

According to issue6330, running chg on heavy loaded systems can lead to
following error:

```
Traceback (most recent call last):
  File "path-to-hg/mercurial/commandserver.py", line 650, in _acceptnewconnection
    self._runworker(conn)
  File "path-to-hg/mercurial/commandserver.py", line 701, in _runworker
    prereposetups=[self._reposetup],
  File "path-to-hg/mercurial/commandserver.py", line 470, in _serverequest
    sv.cleanup()
  File "path-to-hg/mercurial/chgserver.py", line 381, in cleanup
    self._restoreio()
  File "path-to-hg/mercurial/chgserver.py", line 444, in _restoreio
    os.dup2(fd, fp.fileno())
OSError: [Errno 16] Device or resource busy
```

[man dup2] indicates that, on Linux, EBUSY comes from a race condition
between open() and dup2().

However it's not clear why open() race occurred for newfd=stdin/out/err.

We suppress the OSError in _restoreio() since the forked worker process will
finish anyway and add some logging.

Thanks to Mitchell Plamann for a detailed bug description and Yuya Nishihara for
suggesting the fix.

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    "phabricator.uri": "https://phab.mercurial-scm.org/",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}