changeset:   98382:0e7d71a3bf0d
user:        Victor Stinner <victor.stinner@gmail.com>
date:        Tue Sep 29 13:59:50 2015 +0200
files:       Python/pylifecycle.c
description:
Issue #18174: Explain why is_valid_fd() uses dup() instead of fstat()


diff -r 9afc4aca1237 -r 0e7d71a3bf0d Python/pylifecycle.c
--- a/Python/pylifecycle.c	Tue Sep 29 13:47:15 2015 +0200
+++ b/Python/pylifecycle.c	Tue Sep 29 13:59:50 2015 +0200
@@ -972,6 +972,9 @@
     if (fd < 0 || !_PyVerify_fd(fd))
         return 0;
     _Py_BEGIN_SUPPRESS_IPH
+    /* Prefer dup() over fstat(). fstat() can require input/output whereas
+       dup() doesn't, there is a low risk of EMFILE/ENFILE at Python
+       startup. */
     fd2 = dup(fd);
     if (fd2 >= 0)
         close(fd2);