changeset 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.
author Pulkit Goyal <7895pulkit@gmail.com>
date Fri, 03 Jul 2020 13:45:59 +0530
parents b4b6ff83ed9c
children c05ac059749f
files mercurial/chgserver.py
diffstat 1 files changed, 14 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/chgserver.py	Thu Jul 02 19:54:44 2020 +0200
+++ b/mercurial/chgserver.py	Fri Jul 03 13:45:59 2020 +0530
@@ -442,7 +442,20 @@
             if newfp is not fp:
                 newfp.close()
             # restore original fd: fp is open again
-            os.dup2(fd, fp.fileno())
+            try:
+                os.dup2(fd, fp.fileno())
+            except OSError as err:
+                # According to issue6330, running chg on heavy loaded systems
+                # can lead to EBUSY. [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.
+                self.ui.log(
+                    b'chgserver',
+                    b'got %s while duplicating %s\n',
+                    stringutil.forcebytestr(err),
+                    fn,
+                )
             os.close(fd)
             setattr(self, cn, ch)
             setattr(ui, fn, fp)