Issue #25654:
* multiprocessing: open file with closefd=False to avoid ResourceWarning
* _test_multiprocessing: open file with O_EXCL to detect bugs in tests (if a
previous test forgot to remove TESTFN)
* test_sys_exit(): remove TESTFN after each loop iteration
Initial patch written by Serhiy Storchaka.
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 8209ae9..684a59f 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -2689,7 +2689,7 @@
in issues with processes-in-processes. This has been changed to::
sys.stdin.close()
- sys.stdin = open(os.devnull)
+ sys.stdin = open(os.open(os.devnull, os.O_RDONLY), closefd=False)
Which solves the fundamental issue of processes colliding with each other
resulting in a bad file descriptor error, but introduces a potential danger
diff --git a/Lib/multiprocessing/forkserver.py b/Lib/multiprocessing/forkserver.py
index b27cba5..ad01ede 100644
--- a/Lib/multiprocessing/forkserver.py
+++ b/Lib/multiprocessing/forkserver.py
@@ -147,13 +147,7 @@
except ImportError:
pass
- # close sys.stdin
- if sys.stdin is not None:
- try:
- sys.stdin.close()
- sys.stdin = open(os.devnull)
- except (OSError, ValueError):
- pass
+ util._close_stdin()
# ignoring SIGCHLD means no need to reap zombie processes
handler = signal.signal(signal.SIGCHLD, signal.SIG_IGN)
diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py
index 68959bf..bca8b7a 100644
--- a/Lib/multiprocessing/process.py
+++ b/Lib/multiprocessing/process.py
@@ -234,12 +234,7 @@
context._force_start_method(self._start_method)
_process_counter = itertools.count(1)
_children = set()
- if sys.stdin is not None:
- try:
- sys.stdin.close()
- sys.stdin = open(os.devnull)
- except (OSError, ValueError):
- pass
+ util._close_stdin()
old_process = _current_process
_current_process = self
try:
diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py
index ea5443d..1a2c0db 100644
--- a/Lib/multiprocessing/util.py
+++ b/Lib/multiprocessing/util.py
@@ -9,6 +9,7 @@
import os
import itertools
+import sys
import weakref
import atexit
import threading # we want threading to install it's
@@ -356,6 +357,28 @@
assert fds[-1] == MAXFD, 'fd too large'
for i in range(len(fds) - 1):
os.closerange(fds[i]+1, fds[i+1])
+#
+# Close sys.stdin and replace stdin with os.devnull
+#
+
+def _close_stdin():
+ if sys.stdin is None:
+ return
+
+ try:
+ sys.stdin.close()
+ except (OSError, ValueError):
+ pass
+
+ try:
+ fd = os.open(os.devnull, os.O_RDONLY)
+ try:
+ sys.stdin = open(fd, closefd=False)
+ except:
+ os.close(fd)
+ raise
+ except (OSError, ValueError):
+ pass
#
# Start a program with only specified fds kept open
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 1bbbd0b..11a6310 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -455,13 +455,15 @@
@classmethod
def _test_stderr_flush(cls, testfn):
- sys.stderr = open(testfn, 'w')
+ fd = os.open(testfn, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
+ sys.stderr = open(fd, 'w', closefd=False)
1/0 # MARKER
@classmethod
def _test_sys_exit(cls, reason, testfn):
- sys.stderr = open(testfn, 'w')
+ fd = os.open(testfn, os.O_WRONLY | os.O_CREAT | os.O_EXCL)
+ sys.stderr = open(fd, 'w', closefd=False)
sys.exit(reason)
def test_sys_exit(self):
@@ -472,15 +474,21 @@
testfn = test.support.TESTFN
self.addCleanup(test.support.unlink, testfn)
- for reason, code in (([1, 2, 3], 1), ('ignore this', 1)):
+ for reason in (
+ [1, 2, 3],
+ 'ignore this',
+ ):
p = self.Process(target=self._test_sys_exit, args=(reason, testfn))
p.daemon = True
p.start()
p.join(5)
- self.assertEqual(p.exitcode, code)
+ self.assertEqual(p.exitcode, 1)
with open(testfn, 'r') as f:
- self.assertEqual(f.read().rstrip(), str(reason))
+ content = f.read()
+ self.assertEqual(content.rstrip(), str(reason))
+
+ os.unlink(testfn)
for reason in (True, False, 8):
p = self.Process(target=sys.exit, args=(reason,))