Kaydet (Commit) 896145d9 authored tarafından Antoine Pitrou's avatar Antoine Pitrou Kaydeden (comit) GitHub

bpo-26732: fix too many fds in processes started with the "forkserver" method (#2813)

* bpo-26732: fix too many fds in processes started with the "forkserver" method

A child process would inherit as many fds as the number of still-running children.

* Add blurb and test comment
üst 616ecf18
......@@ -236,8 +236,11 @@ def main(listener_fd, alive_r, preload, main_path=None, sys_path=None):
code = 1
try:
listener.close()
selector.close()
unused_fds = [alive_r, child_w, sig_r, sig_w]
unused_fds.extend(pid_to_fd.values())
code = _serve_one(child_r, fds,
(alive_r, child_w, sig_r, sig_w),
unused_fds,
old_handlers)
except Exception:
sys.excepthook(*sys.exc_info())
......
......@@ -494,6 +494,40 @@ class _TestProcess(BaseTestCase):
self.assertIs(wr(), None)
self.assertEqual(q.get(), 5)
@classmethod
def _test_child_fd_inflation(self, evt, q):
q.put(test.support.fd_count())
evt.wait()
def test_child_fd_inflation(self):
# Number of fds in child processes should not grow with the
# number of running children.
if self.TYPE == 'threads':
self.skipTest('test not appropriate for {}'.format(self.TYPE))
sm = multiprocessing.get_start_method()
if sm == 'fork':
# The fork method by design inherits all fds from the parent,
# trying to go against it is a lost battle
self.skipTest('test not appropriate for {}'.format(sm))
N = 5
evt = self.Event()
q = self.Queue()
procs = [self.Process(target=self._test_child_fd_inflation, args=(evt, q))
for i in range(N)]
for p in procs:
p.start()
try:
fd_counts = [q.get() for i in range(N)]
self.assertEqual(len(set(fd_counts)), 1, fd_counts)
finally:
evt.set()
for p in procs:
p.join()
#
#
......
......@@ -7,36 +7,6 @@ from inspect import isabstract
from test import support
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
except Exception:
MAXFD = 256
def fd_count():
"""Count the number of open file descriptors"""
if sys.platform.startswith(('linux', 'freebsd')):
try:
names = os.listdir("/proc/self/fd")
return len(names)
except FileNotFoundError:
pass
count = 0
for fd in range(MAXFD):
try:
# Prefer dup() over fstat(). fstat() can require input/output
# whereas dup() doesn't.
fd2 = os.dup(fd)
except OSError as e:
if e.errno != errno.EBADF:
raise
else:
os.close(fd2)
count += 1
return count
def dash_R(the_module, test, indirect_test, huntrleaks):
"""Run a test multiple times, looking for reference leaks.
......@@ -174,7 +144,7 @@ def dash_R_cleanup(fs, ps, pic, zdc, abcs):
func1 = sys.getallocatedblocks
func2 = sys.gettotalrefcount
gc.collect()
return func1(), func2(), fd_count()
return func1(), func2(), support.fd_count()
def clear_caches():
......
......@@ -107,7 +107,7 @@ __all__ = [
"check_warnings", "check_no_resource_warning", "EnvironmentVarGuard",
"run_with_locale", "swap_item",
"swap_attr", "Matcher", "set_memlimit", "SuppressCrashReport", "sortdict",
"run_with_tz", "PGO", "missing_compiler_executable",
"run_with_tz", "PGO", "missing_compiler_executable", "fd_count",
]
class Error(Exception):
......@@ -2647,3 +2647,34 @@ def disable_faulthandler():
finally:
if is_enabled:
faulthandler.enable(file=fd, all_threads=True)
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
except Exception:
MAXFD = 256
def fd_count():
"""Count the number of open file descriptors.
"""
if sys.platform.startswith(('linux', 'freebsd')):
try:
names = os.listdir("/proc/self/fd")
return len(names)
except FileNotFoundError:
pass
count = 0
for fd in range(MAXFD):
try:
# Prefer dup() over fstat(). fstat() can require input/output
# whereas dup() doesn't.
fd2 = os.dup(fd)
except OSError as e:
if e.errno != errno.EBADF:
raise
else:
os.close(fd2)
count += 1
return count
Fix too many fds in processes started with the "forkserver" method.
A child process would inherit as many fds as the number of still-running
children.
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