openstack/swift
Code Issues Proposed changes

Per device replication_lock

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New replication_one_per_device (True by default)
that restricts incoming REPLICATION requests to
one per device, replication_currency allowing.

Also has replication_lock_timeout (15 by default)
to control how long a request will wait to obtain
a replication device lock before giving up.

This should be very useful in that you can be
assured any concurrent REPLICATION requests are
each writing to distinct devices. If you have 100
devices on a server, you can set
replication_concurrency to 100 and be confident
that, even if 100 replication requests were
executing concurrently, they'd each be writing to
separate devices. Before, all 100 could end up
writing to the same device, bringing it to a
horrible crawl.

NOTE: This is only for ssync replication. The
current default rsync replication still has the
potentially horrible behavior.

Change-Id: I36e99a3d7e100699c76db6d3a4846514537ff685
This commit is contained in:
gholt 2013-11-09 03:18:11 +00:00
parent c850580566
commit c859ebf5ce
10 changed files with 240 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
doc/source/deployment_guide.rst
View File

@ -408,6 +408,19 @@ threads_per_disk 0 Size of the per-disk thread pool
replication_concurrency 4 Set to restrict the number of
concurrent incoming REPLICATION
requests; set to 0 for unlimited
replication_one_per_device True Restricts incoming REPLICATION
requests to one per device,
replication_currency above
allowing. This can help control
I/O to each device, but you may
wish to set this to False to
allow multiple REPLICATION
requests (up to the above
replication_concurrency setting)
per device.
replication_lock_timeout 15 Number of seconds to wait for an
existing replication device lock
before giving up.
replication_failure_threshold 100 The number of subrequest failures
before the
replication_failure_ratio is

10
etc/object-server.conf-sample
View File

@ -105,6 +105,16 @@ use = egg:swift#object
# Note that REPLICATION is currently an ssync only item
# replication_concurrency = 4
#
# Restricts incoming REPLICATION requests to one per device,
# replication_currency above allowing. This can help control I/O to each
# device, but you may wish to set this to False to allow multiple REPLICATION
# requests (up to the above replication_concurrency setting) per device.
# replication_one_per_device = True
#
# Number of seconds to wait for an existing replication device lock before
# giving up.
# replication_lock_timeout = 15
#
# These next two settings control when the REPLICATION subrequest handler will
# abort an incoming REPLICATION attempt. An abort will occur if there are at
# least threshold number of failures and the value of failures / successes

4
swift/common/exceptions.py
View File

@ -122,3 +122,7 @@ class SegmentError(SwiftException):
class ReplicationException(Exception):
pass
class ReplicationLockTimeout(LockTimeout):
pass

8
swift/common/utils.py
View File

@ -1179,7 +1179,7 @@ def hash_path(account, container=None, object=None, raw_digest=False):
@contextmanager
def lock_path(directory, timeout=10):
def lock_path(directory, timeout=10, timeout_class=LockTimeout):
"""
Context manager that acquires a lock on a directory. This will block until
the lock can be acquired, or the timeout time has expired (whichever occurs
@ -1191,12 +1191,16 @@ def lock_path(directory, timeout=10):
:param directory: directory to be locked
:param timeout: timeout (in seconds)
:param timeout_class: The class of the exception to raise if the
lock cannot be granted within the timeout. Will be
constructed as timeout_class(timeout, lockpath). Default:
LockTimeout
"""
mkdirs(directory)
lockpath = '%s/.lock' % directory
fd = os.open(lockpath, os.O_WRONLY | os.O_CREAT)
try:
with LockTimeout(timeout, lockpath):
with timeout_class(timeout, lockpath):
while True:
try:
fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)

26
swift/obj/diskfile.py
View File

@ -56,7 +56,8 @@ from swift.common.utils import mkdirs, normalize_timestamp, \
config_true_value, listdir, split_path, ismount
from swift.common.exceptions import DiskFileQuarantined, DiskFileNotExist, \
DiskFileCollision, DiskFileNoSpace, DiskFileDeviceUnavailable, \
DiskFileDeleted, DiskFileError, DiskFileNotOpen, PathNotDir
DiskFileDeleted, DiskFileError, DiskFileNotOpen, PathNotDir, \
ReplicationLockTimeout
from swift.common.swob import multi_range_iterator
@ -382,6 +383,10 @@ class DiskFileManager(object):
self.bytes_per_sync = int(conf.get('mb_per_sync', 512)) * 1024 * 1024
self.mount_check = config_true_value(conf.get('mount_check', 'true'))
self.reclaim_age = int(conf.get('reclaim_age', ONE_WEEK))
self.replication_one_per_device = config_true_value(
conf.get('replication_one_per_device', 'true'))
self.replication_lock_timeout = int(conf.get(
'replication_lock_timeout', 15))
threads_per_disk = int(conf.get('threads_per_disk', '0'))
self.threadpools = defaultdict(
lambda: ThreadPool(nthreads=threads_per_disk))
@ -413,6 +418,25 @@ class DiskFileManager(object):
dev_path = os.path.join(self.devices, device)
return dev_path
@contextmanager
def replication_lock(self, device):
"""
A context manager that will lock on the device given, if
configured to do so.
:raises ReplicationLockTimeout: If the lock on the device
cannot be granted within the configured timeout.
"""
if self.replication_one_per_device:
dev_path = self.get_dev_path(device)
with lock_path(
dev_path,
timeout=self.replication_lock_timeout,
timeout_class=ReplicationLockTimeout):
yield True
else:
yield True
def pickle_async_update(self, device, account, container, obj, data,
timestamp):
device_path = self.construct_dev_path(device)

15
swift/obj/ssync_receiver.py
View File

@ -97,13 +97,20 @@ class Receiver(object):
if not self.app.replication_semaphore.acquire(False):
raise swob.HTTPServiceUnavailable()
try:
for data in self.missing_check():
yield data
for data in self.updates():
yield data
with self.app._diskfile_mgr.replication_lock(self.device):
for data in self.missing_check():
yield data
for data in self.updates():
yield data
finally:
if self.app.replication_semaphore:
self.app.replication_semaphore.release()
except exceptions.ReplicationLockTimeout as err:
self.app.logger.debug(
'%s/%s/%s REPLICATION LOCK TIMEOUT: %s' % (
self.request.remote_addr, self.device, self.partition,
err))
yield ':ERROR: %d %r\n' % (0, str(err))
except exceptions.MessageTimeout as err:
self.app.logger.error(
'%s/%s/%s TIMEOUT in replication.Receiver: %s' % (

7
test/unit/common/test_exceptions.py
View File

@ -25,6 +25,13 @@ class TestExceptions(unittest.TestCase):
self.assertEqual(str(exceptions.ReplicationException()), '')
self.assertEqual(str(exceptions.ReplicationException('test')), 'test')
def test_replication_lock_timeout(self):
exc = exceptions.ReplicationLockTimeout(15, 'test')
try:
self.assertTrue(isinstance(exc, exceptions.MessageTimeout))
finally:
exc.cancel()
if __name__ == '__main__':
unittest.main()

52
test/unit/common/test_utils.py
View File

@ -49,7 +49,8 @@ from netifaces import AF_INET6
from mock import MagicMock, patch
from swift.common.exceptions import (Timeout, MessageTimeout,
ConnectionTimeout, LockTimeout)
ConnectionTimeout, LockTimeout,
ReplicationLockTimeout)
from swift.common import utils
from swift.common.swob import Response
from test.unit import FakeLogger
@ -138,6 +139,55 @@ class TestUtils(unittest.TestCase):
utils.HASH_PATH_SUFFIX = 'endcap'
utils.HASH_PATH_PREFIX = 'startcap'
def test_lock_path(self):
tmpdir = mkdtemp()
try:
with utils.lock_path(tmpdir, 0.1):
exc = None
success = False
try:
with utils.lock_path(tmpdir, 0.1):
success = True
except LockTimeout as err:
exc = err
self.assertTrue(exc is not None)
self.assertTrue(not success)
finally:
shutil.rmtree(tmpdir)
def test_lock_path_class(self):
tmpdir = mkdtemp()
try:
with utils.lock_path(tmpdir, 0.1, ReplicationLockTimeout):
exc = None
exc2 = None
success = False
try:
with utils.lock_path(tmpdir, 0.1, ReplicationLockTimeout):
success = True
except ReplicationLockTimeout as err:
exc = err
except LockTimeout as err:
exc2 = err
self.assertTrue(exc is not None)
self.assertTrue(exc2 is None)
self.assertTrue(not success)
exc = None
exc2 = None
success = False
try:
with utils.lock_path(tmpdir, 0.1):
success = True
except ReplicationLockTimeout as err:
exc = err
except LockTimeout as err:
exc2 = err
self.assertTrue(exc is None)
self.assertTrue(exc2 is not None)
self.assertTrue(not success)
finally:
shutil.rmtree(tmpdir)
def test_normalize_timestamp(self):
# Test swift.common.utils.normalize_timestamp
self.assertEquals(utils.normalize_timestamp('1253327593.48174'),

69
test/unit/obj/test_diskfile.py
View File

@ -41,7 +41,8 @@ from swift.common import utils
from swift.common.utils import hash_path, mkdirs, normalize_timestamp
from swift.common import ring
from swift.common.exceptions import DiskFileNotExist, DiskFileQuarantined, \
DiskFileDeviceUnavailable, DiskFileDeleted, DiskFileNotOpen, DiskFileError
DiskFileDeviceUnavailable, DiskFileDeleted, DiskFileNotOpen, \
DiskFileError, ReplicationLockTimeout
def _create_test_ring(path):
@ -468,6 +469,72 @@ class TestObjectAuditLocationGenerator(unittest.TestCase):
self.assertRaises(OSError, list_locations, tmpdir)
class TestDiskFileManager(unittest.TestCase):
def setUp(self):
self.testdir = os.path.join(mkdtemp(), 'tmp_test_obj_server_DiskFile')
mkdirs(os.path.join(self.testdir, 'sda1', 'tmp'))
mkdirs(os.path.join(self.testdir, 'sda2', 'tmp'))
self._orig_tpool_exc = tpool.execute
tpool.execute = lambda f, *args, **kwargs: f(*args, **kwargs)
self.conf = dict(devices=self.testdir, mount_check='false',
keep_cache_size=2 * 1024)
self.df_mgr = diskfile.DiskFileManager(self.conf, FakeLogger())
def test_replication_lock_on(self):
# Double check settings
self.df_mgr.replication_one_per_device = True
self.df_mgr.replication_lock_timeout = 0.1
dev_path = os.path.join(self.testdir, 'sda1')
with self.df_mgr.replication_lock(dev_path):
lock_exc = None
exc = None
try:
with self.df_mgr.replication_lock(dev_path):
raise Exception(
'%r was not replication locked!' % dev_path)
except ReplicationLockTimeout as err:
lock_exc = err
except Exception as err:
exc = err
self.assertTrue(lock_exc is not None)
self.assertTrue(exc is None)
def test_replication_lock_off(self):
# Double check settings
self.df_mgr.replication_one_per_device = False
self.df_mgr.replication_lock_timeout = 0.1
dev_path = os.path.join(self.testdir, 'sda1')
with self.df_mgr.replication_lock(dev_path):
lock_exc = None
exc = None
try:
with self.df_mgr.replication_lock(dev_path):
raise Exception(
'%r was not replication locked!' % dev_path)
except ReplicationLockTimeout as err:
lock_exc = err
except Exception as err:
exc = err
self.assertTrue(lock_exc is None)
self.assertTrue(exc is not None)
def test_replication_lock_another_device_fine(self):
# Double check settings
self.df_mgr.replication_one_per_device = True
self.df_mgr.replication_lock_timeout = 0.1
dev_path = os.path.join(self.testdir, 'sda1')
dev_path2 = os.path.join(self.testdir, 'sda2')
with self.df_mgr.replication_lock(dev_path):
lock_exc = None
try:
with self.df_mgr.replication_lock(dev_path2):
pass
except ReplicationLockTimeout as err:
lock_exc = err
self.assertTrue(lock_exc is None)
class TestDiskFile(unittest.TestCase):
"""Test swift.obj.diskfile.DiskFile"""

46
test/unit/obj/test_ssync_receiver.py
View File

@ -24,6 +24,7 @@ import eventlet
import mock
from swift.common import constraints
from swift.common import exceptions
from swift.common import swob
from swift.common import utils
from swift.obj import diskfile
@ -45,7 +46,10 @@ class TestReceiver(unittest.TestCase):
self.testdir = os.path.join(
tempfile.mkdtemp(), 'tmp_test_ssync_receiver')
utils.mkdirs(os.path.join(self.testdir, 'sda1', 'tmp'))
conf = {'devices': self.testdir, 'mount_check': 'false'}
conf = {
'devices': self.testdir,
'mount_check': 'false',
'replication_one_per_device': 'false'}
self.controller = server.ObjectController(conf)
self.controller.bytes_per_sync = 1
@ -104,6 +108,46 @@ class TestReceiver(unittest.TestCase):
self.assertFalse(self.controller.logger.error.called)
self.assertFalse(self.controller.logger.exception.called)
def test_REPLICATION_calls_replication_lock(self):
with mock.patch.object(
self.controller._diskfile_mgr, 'replication_lock') as \
mocked_replication_lock:
req = swob.Request.blank(
'/sda1/1',
environ={'REQUEST_METHOD': 'REPLICATION'},
body=':MISSING_CHECK: START\r\n'
':MISSING_CHECK: END\r\n'
':UPDATES: START\r\n:UPDATES: END\r\n')
resp = self.controller.REPLICATION(req)
self.assertEqual(
self.body_lines(resp.body),
[':MISSING_CHECK: START', ':MISSING_CHECK: END',
':UPDATES: START', ':UPDATES: END'])
self.assertEqual(resp.status_int, 200)
mocked_replication_lock.assert_called_once_with('sda1')
def test_REPLICATION_replication_lock_fail(self):
def _mock(path):
with exceptions.ReplicationLockTimeout(0.01, '/somewhere/' + path):
eventlet.sleep(0.05)
with mock.patch.object(
self.controller._diskfile_mgr, 'replication_lock', _mock):
self.controller._diskfile_mgr
self.controller.logger = mock.MagicMock()
req = swob.Request.blank(
'/sda1/1',
environ={'REQUEST_METHOD': 'REPLICATION'},
body=':MISSING_CHECK: START\r\n'
':MISSING_CHECK: END\r\n'
':UPDATES: START\r\n:UPDATES: END\r\n')
resp = self.controller.REPLICATION(req)
self.assertEqual(
self.body_lines(resp.body),
[":ERROR: 0 '0.01 seconds: /somewhere/sda1'"])
self.controller.logger.debug.assert_called_once_with(
'None/sda1/1 REPLICATION LOCK TIMEOUT: 0.01 seconds: '
'/somewhere/sda1')
def test_REPLICATION_initial_path(self):
with mock.patch.object(
self.controller, 'replication_semaphore') as \