Add prlimit parameter to execute()

Add a new oslo_concurrency.prlimit module which is written to be used
on the command line:

    python -m oslo_concurrency.prlimit --rss=RSS -- program arg1 ...

This module calls setrlimit() to restrict the resources and then
executes the program. Its command line is written to be the same than
the Linux prlimit system program.

Add a new ProcessLimits class processutils: resource limits on a
process.

Add an optional prlimit parameter to process_utils.execute(). If the
parameter is used, wrap the command through the new oslo_concurrency
prlimit wrapper.

Linux provides a prlimit command line tool which implements the same
feature (and even more), but it requires util-linux v2.21, and
OpenStack targets other operating systems like Solaris and FreeBSD.

Change-Id: Ib40aa62958ab9c157a2bd51d7ff3edb445556285
Related-Bug: 1449062
This commit is contained in:
Victor Stinner 2015-11-10 22:20:47 +01:00
parent 70118c268f
commit b2e78569c5
3 changed files with 250 additions and 0 deletions

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@ -0,0 +1,89 @@
# Copyright 2016 Red Hat.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from __future__ import print_function
import argparse
import os
import resource
import sys
USAGE_PROGRAM = ('%s -m oslo_concurrency.prlimit'
% os.path.basename(sys.executable))
RESOURCES = (
# argparse argument => resource
('as', resource.RLIMIT_AS),
('nofile', resource.RLIMIT_NOFILE),
('rss', resource.RLIMIT_RSS),
)
def parse_args():
parser = argparse.ArgumentParser(description='prlimit', prog=USAGE_PROGRAM)
parser.add_argument('--as', type=int,
help='Address space limit in bytes')
parser.add_argument('--nofile', type=int,
help='Maximum number of open files')
parser.add_argument('--rss', type=int,
help='Maximum Resident Set Size (RSS) in bytes')
parser.add_argument('program',
help='Program (absolute path)')
parser.add_argument('program_args', metavar="arg", nargs='...',
help='Program parameters')
args = parser.parse_args()
return args
def main():
args = parse_args()
program = args.program
if not os.path.isabs(program):
# program uses a relative path: try to find the absolute path
# to the executable
if sys.version_info >= (3, 3):
import shutil
program_abs = shutil.which(program)
else:
import distutils.spawn
program_abs = distutils.spawn.find_executable(program)
if program_abs:
program = program_abs
for arg_name, rlimit in RESOURCES:
value = getattr(args, arg_name)
if value is None:
continue
try:
resource.setrlimit(rlimit, (value, value))
except ValueError as exc:
print("%s: failed to set the %s resource limit: %s"
% (USAGE_PROGRAM, arg_name.upper(), exc),
file=sys.stderr)
sys.exit(1)
try:
os.execv(program, [program] + args.program_args)
except Exception as exc:
print("%s: failed to execute %s: %s"
% (USAGE_PROGRAM, program, exc),
file=sys.stderr)
sys.exit(1)
if __name__ == "__main__":
main()

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@ -24,6 +24,7 @@ import os
import random
import shlex
import signal
import sys
import time
import enum
@ -120,6 +121,38 @@ LOG_FINAL_ERROR = LogErrors.FINAL
LOG_DEFAULT_ERROR = LogErrors.DEFAULT
class ProcessLimits(object):
"""Resource limits on a process.
Attributes:
* address_space: Address space limit in bytes
* number_files: Maximum number of open files.
* resident_set_size: Maximum Resident Set Size (RSS) in bytes
This object can be used for the *prlimit* parameter of :func:`execute`.
"""
def __init__(self, **kw):
self.address_space = kw.pop('address_space', None)
self.number_files = kw.pop('number_files', None)
self.resident_set_size = kw.pop('resident_set_size', None)
if kw:
raise ValueError("invalid limits: %s"
% ', '.join(sorted(kw.keys())))
def prlimit_args(self):
"""Create a list of arguments for the prlimit command line."""
args = []
if self.address_space:
args.append('--as=%s' % self.address_space)
if self.number_files:
args.append('--nofile=%s' % self.number_files)
if self.resident_set_size:
args.append('--rss=%s' % self.resident_set_size)
return args
def execute(*cmd, **kwargs):
"""Helper method to shell out and execute a command through subprocess.
@ -188,12 +221,22 @@ def execute(*cmd, **kwargs):
subprocess.Popen on windows (throws a
ValueError)
:type preexec_fn: function()
:param prlimit: Set resource limits on the child process. See
below for a detailed description.
:type prlimit: :class:`ProcessLimits`
:returns: (stdout, stderr) from process execution
:raises: :class:`UnknownArgumentError` on
receiving unknown arguments
:raises: :class:`ProcessExecutionError`
:raises: :class:`OSError`
The *prlimit* parameter can be used to set resource limits on the child
process. If this parameter is used, the child process will be spawned by a
wrapper process which will set limits before spawning the command.
.. versionchanged:: 3.4
Added *prlimit* optional parameter.
.. versionchanged:: 1.5
Added *cwd* optional parameter.
@ -227,6 +270,7 @@ def execute(*cmd, **kwargs):
on_execute = kwargs.pop('on_execute', None)
on_completion = kwargs.pop('on_completion', None)
preexec_fn = kwargs.pop('preexec_fn', None)
prlimit = kwargs.pop('prlimit', None)
if isinstance(check_exit_code, bool):
ignore_exit_code = not check_exit_code
@ -256,6 +300,14 @@ def execute(*cmd, **kwargs):
cmd = shlex.split(root_helper) + list(cmd)
cmd = [str(c) for c in cmd]
if prlimit:
args = [sys.executable, '-m', 'oslo_concurrency.prlimit']
args.extend(prlimit.prlimit_args())
args.append('--')
args.extend(cmd)
cmd = args
sanitized_cmd = strutils.mask_password(' '.join(cmd))
watch = timeutils.StopWatch()

View File

@ -19,6 +19,7 @@ import errno
import logging
import multiprocessing
import os
import resource
import stat
import subprocess
import sys
@ -724,3 +725,111 @@ class SshExecuteTestCase(test_base.BaseTestCase):
def test_compromising_ssh6(self):
self._test_compromising_ssh(rc=-1, check=False)
class PrlimitTestCase(test_base.BaseTestCase):
# Simply program that does nothing and returns an exit code 0.
# Use Python to be portable.
SIMPLE_PROGRAM = [sys.executable, '-c', 'pass']
def soft_limit(self, res, substract, default_limit):
# Create a new soft limit for a resource, lower than the current
# soft limit.
soft_limit, hard_limit = resource.getrlimit(res)
if soft_limit < 0:
soft_limit = default_limit
else:
soft_limit -= substract
return soft_limit
def memory_limit(self, res):
# Substract 1 kB just to get a different limit. Don't substract too
# much to avoid memory allocation issues.
#
# Use 1 GB by default. Limit high enough to be able to load shared
# libraries. Limit low enough to be work on 32-bit platforms.
return self.soft_limit(res, 1024, 1024 ** 3)
def limit_address_space(self):
max_memory = self.memory_limit(resource.RLIMIT_AS)
return processutils.ProcessLimits(address_space=max_memory)
def test_simple(self):
# Simple test running a program (/bin/true) with no parameter
prlimit = self.limit_address_space()
stdout, stderr = processutils.execute(*self.SIMPLE_PROGRAM,
prlimit=prlimit)
self.assertEqual(stdout.rstrip(), '')
self.assertEqual(stderr.rstrip(), '')
def check_limit(self, prlimit, resource, value):
code = ';'.join(('import resource',
'print(resource.getrlimit(resource.%s))' % resource))
args = [sys.executable, '-c', code]
stdout, stderr = processutils.execute(*args, prlimit=prlimit)
expected = (value, value)
self.assertEqual(stdout.rstrip(), str(expected))
def test_address_space(self):
prlimit = self.limit_address_space()
self.check_limit(prlimit, 'RLIMIT_AS', prlimit.address_space)
def test_resident_set_size(self):
max_memory = self.memory_limit(resource.RLIMIT_RSS)
prlimit = processutils.ProcessLimits(resident_set_size=max_memory)
self.check_limit(prlimit, 'RLIMIT_RSS', max_memory)
def test_number_files(self):
nfiles = self.soft_limit(resource.RLIMIT_NOFILE, 1, 1024)
prlimit = processutils.ProcessLimits(number_files=nfiles)
self.check_limit(prlimit, 'RLIMIT_NOFILE', nfiles)
def test_unsupported_prlimit(self):
self.assertRaises(ValueError, processutils.ProcessLimits, xxx=33)
def test_relative_path(self):
prlimit = self.limit_address_space()
program = sys.executable
env = dict(os.environ)
env['PATH'] = os.path.dirname(program)
args = [os.path.basename(program), '-c', 'pass']
processutils.execute(*args, prlimit=prlimit, env_variables=env)
def test_execv_error(self):
prlimit = self.limit_address_space()
args = ['/missing_path/dont_exist/program']
try:
processutils.execute(*args, prlimit=prlimit)
except processutils.ProcessExecutionError as exc:
self.assertEqual(exc.exit_code, 1)
self.assertEqual(exc.stdout, '')
expected = ('%s -m oslo_concurrency.prlimit: '
'failed to execute /missing_path/dont_exist/program: '
% os.path.basename(sys.executable))
self.assertIn(expected, exc.stderr)
else:
self.fail("ProcessExecutionError not raised")
def test_setrlimit_error(self):
prlimit = self.limit_address_space()
# trying to set a limit higher than the current hard limit
# with setrlimit() should fail.
higher_limit = prlimit.address_space + 1024
args = [sys.executable, '-m', 'oslo_concurrency.prlimit',
'--as=%s' % higher_limit,
'--']
args.extend(self.SIMPLE_PROGRAM)
try:
processutils.execute(*args, prlimit=prlimit)
except processutils.ProcessExecutionError as exc:
self.assertEqual(exc.exit_code, 1)
self.assertEqual(exc.stdout, '')
expected = ('%s -m oslo_concurrency.prlimit: '
'failed to set the AS resource limit: '
% os.path.basename(sys.executable))
self.assertIn(expected, exc.stderr)
else:
self.fail("ProcessExecutionError not raised")