"""
Thrash mds by simulating failures
"""
import logging
import contextlib
import ceph_manager
import random
import time
from gevent.greenlet import Greenlet
from gevent.event import Event
from teuthology import misc as teuthology
log = logging.getLogger(__name__)
class MDSThrasher(Greenlet):
"""
MDSThrasher::
The MDSThrasher thrashes MDSs during execution of other tasks (workunits, etc).
The config is optional. Many of the config parameters are a a maximum value
to use when selecting a random value from a range. To always use the maximum
value, set no_random to true. The config is a dict containing some or all of:
seed: [no default] seed the random number generator
randomize: [default: true] enables randomization and use the max/min values
max_thrash: [default: 1] the maximum number of MDSs that will be thrashed at
any given time.
max_thrash_delay: [default: 30] maximum number of seconds to delay before
thrashing again.
max_revive_delay: [default: 10] maximum number of seconds to delay before
bringing back a thrashed MDS
thrash_in_replay: [default: 0.0] likelihood that the MDS will be thrashed
during replay. Value should be between 0.0 and 1.0
max_replay_thrash_delay: [default: 4] maximum number of seconds to delay while in
the replay state before thrashing
thrash_weights: allows specific MDSs to be thrashed more/less frequently. This option
overrides anything specified by max_thrash. This option is a dict containing
mds.x: weight pairs. For example, [mds.a: 0.7, mds.b: 0.3, mds.c: 0.0]. Each weight
is a value from 0.0 to 1.0. Any MDSs not specified will be automatically
given a weight of 0.0. For a given MDS, by default the trasher delays for up
to max_thrash_delay, trashes, waits for the MDS to recover, and iterates. If a non-zero
weight is specified for an MDS, for each iteration the thrasher chooses whether to thrash
during that iteration based on a random value [0-1] not exceeding the weight of that MDS.
Examples::
The following example sets the likelihood that mds.a will be thrashed
to 80%, mds.b to 20%, and other MDSs will not be thrashed. It also sets the
likelihood that an MDS will be thrashed in replay to 40%.
Thrash weights do not have to sum to 1.
tasks:
- ceph:
- mds_thrash:
thrash_weights:
- mds.a: 0.8
- mds.b: 0.2
thrash_in_replay: 0.4
- ceph-fuse:
- workunit:
clients:
all: [suites/fsx.sh]
The following example disables randomization, and uses the max delay values:
tasks:
- ceph:
- mds_thrash:
max_thrash_delay: 10
max_revive_delay: 1
max_replay_thrash_delay: 4
"""
def __init__(self, ctx, manager, config, logger, failure_group, weight):
super(MDSThrasher, self).__init__()
self.ctx = ctx
self.manager = manager
assert self.manager.is_clean()
self.stopping = Event()
self.logger = logger
self.config = config
self.randomize = bool(self.config.get('randomize', True))
self.max_thrash_delay = float(self.config.get('thrash_delay', 30.0))
self.thrash_in_replay = float(self.config.get('thrash_in_replay', False))
assert self.thrash_in_replay >= 0.0 and self.thrash_in_replay <= 1.0, 'thrash_in_replay ({v}) must be between [0.0, 1.0]'.format(
v=self.thrash_in_replay)
self.max_replay_thrash_delay = float(self.config.get('max_replay_thrash_delay', 4.0))
self.max_revive_delay = float(self.config.get('max_revive_delay', 10.0))
self.failure_group = failure_group
self.weight = weight
def _run(self):
try:
self.do_thrash()
except:
# Log exceptions here so we get the full backtrace (it's lost
# by the time someone does a .get() on this greenlet)
self.logger.exception("Exception in do_thrash:")
raise
def log(self, x):
"""Write data to logger assigned to this MDThrasher"""
self.logger.info(x)
def stop(self):
self.stopping.set()
def do_thrash(self):
"""
Perform the random thrashing action
"""
self.log('starting mds_do_thrash for failure group: ' + ', '.join(
['mds.{_id}'.format(_id=_f) for _f in self.failure_group]))
while not self.stopping.is_set():
delay = self.max_thrash_delay
if self.randomize:
delay = random.randrange(0.0, self.max_thrash_delay)
if delay > 0.0:
self.log('waiting for {delay} secs before thrashing'.format(delay=delay))
self.stopping.wait(delay)
if self.stopping.is_set():
continue
skip = random.randrange(0.0, 1.0)
if self.weight < 1.0 and skip > self.weight:
self.log('skipping thrash iteration with skip ({skip}) > weight ({weight})'.format(skip=skip,
weight=self.weight))
continue
# find the active mds in the failure group
statuses = [self.manager.get_mds_status(m) for m in self.failure_group]
actives = filter(lambda s: s and s['state'] == 'up:active', statuses)
assert len(actives) == 1, 'Can only have one active in a failure group'
active_mds = actives[0]['name']
active_rank = actives[0]['rank']
self.log('kill mds.{id} (rank={r})'.format(id=active_mds, r=active_rank))
self.manager.kill_mds_by_rank(active_rank)
# wait for mon to report killed mds as crashed
last_laggy_since = None
itercount = 0
while True:
failed = self.manager.get_mds_status_all()['failed']
status = self.manager.get_mds_status(active_mds)
if not status:
break
if 'laggy_since' in status:
last_laggy_since = status['laggy_since']
break
if any([(f == active_mds) for f in failed]):
break
self.log(
'waiting till mds map indicates mds.{_id} is laggy/crashed, in failed state, or mds.{_id} is removed from mdsmap'.format(
_id=active_mds))
itercount = itercount + 1
if itercount > 10:
self.log('mds map: {status}'.format(status=self.manager.get_mds_status_all()))
time.sleep(2)
if last_laggy_since:
self.log(
'mds.{_id} reported laggy/crashed since: {since}'.format(_id=active_mds, since=last_laggy_since))
else:
self.log('mds.{_id} down, removed from mdsmap'.format(_id=active_mds, since=last_laggy_since))
# wait for a standby mds to takeover and become active
takeover_mds = None
takeover_rank = None
itercount = 0
while True:
statuses = [self.manager.get_mds_status(m) for m in self.failure_group]
actives = filter(lambda s: s and s['state'] == 'up:active', statuses)
if len(actives) > 0:
assert len(actives) == 1, 'Can only have one active in failure group'
takeover_mds = actives[0]['name']
takeover_rank = actives[0]['rank']
break
itercount = itercount + 1
if itercount > 10:
self.log('mds map: {status}'.format(status=self.manager.get_mds_status_all()))
self.log('New active mds is mds.{_id}'.format(_id=takeover_mds))
# wait for a while before restarting old active to become new
# standby
delay = self.max_revive_delay
if self.randomize:
delay = random.randrange(0.0, self.max_revive_delay)
self.log('waiting for {delay} secs before reviving mds.{id}'.format(
delay=delay, id=active_mds))
time.sleep(delay)
self.log('reviving mds.{id}'.format(id=active_mds))
self.manager.revive_mds(active_mds, standby_for_rank=takeover_rank)
status = {}
while True:
status = self.manager.get_mds_status(active_mds)
if status and (status['state'] == 'up:standby' or status['state'] == 'up:standby-replay'):
break
self.log(
'waiting till mds map indicates mds.{_id} is in standby or standby-replay'.format(_id=active_mds))
time.sleep(2)
self.log('mds.{_id} reported in {state} state'.format(_id=active_mds, state=status['state']))
# don't do replay thrashing right now
continue
# this might race with replay -> active transition...
if status['state'] == 'up:replay' and random.randrange(0.0, 1.0) < self.thrash_in_replay:
delay = self.max_replay_thrash_delay
if self.randomize:
delay = random.randrange(0.0, self.max_replay_thrash_delay)
time.sleep(delay)
self.log('kill replaying mds.{id}'.format(id=self.to_kill))
self.manager.kill_mds(self.to_kill)
delay = self.max_revive_delay
if self.randomize:
delay = random.randrange(0.0, self.max_revive_delay)
self.log('waiting for {delay} secs before reviving mds.{id}'.format(
delay=delay, id=self.to_kill))
time.sleep(delay)
self.log('revive mds.{id}'.format(id=self.to_kill))
self.manager.revive_mds(self.to_kill)
@contextlib.contextmanager
def task(ctx, config):
"""
Stress test the mds by thrashing while another task/workunit
is running.
Please refer to MDSThrasher class for further information on the
available options.
"""
if config is None:
config = {}
assert isinstance(config, dict), \
'mds_thrash task only accepts a dict for configuration'
mdslist = list(teuthology.all_roles_of_type(ctx.cluster, 'mds'))
assert len(mdslist) > 1, \
'mds_thrash task requires at least 2 metadata servers'
# choose random seed
seed = None
if 'seed' in config:
seed = int(config['seed'])
else:
seed = int(time.time())
log.info('mds thrasher using random seed: {seed}'.format(seed=seed))
random.seed(seed)
max_thrashers = config.get('max_thrash', 1)
thrashers = {}
(first,) = ctx.cluster.only('mds.{_id}'.format(_id=mdslist[0])).remotes.iterkeys()
manager = ceph_manager.CephManager(
first, ctx=ctx, logger=log.getChild('ceph_manager'),
)
# make sure everyone is in active, standby, or standby-replay
log.info('Wait for all MDSs to reach steady state...')
statuses = None
statuses_by_rank = None
while True:
statuses = {m: manager.get_mds_status(m) for m in mdslist}
statuses_by_rank = {}
for _, s in statuses.iteritems():
if isinstance(s, dict):
statuses_by_rank[s['rank']] = s
ready = filter(lambda (_, s): s is not None and (s['state'] == 'up:active'
or s['state'] == 'up:standby'
or s['state'] == 'up:standby-replay'),
statuses.items())
if len(ready) == len(statuses):
break
time.sleep(2)
log.info('Ready to start thrashing')
# setup failure groups
failure_groups = {}
actives = {s['name']: s for (_, s) in statuses.iteritems() if s['state'] == 'up:active'}
log.info('Actives is: {d}'.format(d=actives))
log.info('Statuses is: {d}'.format(d=statuses_by_rank))
for active in actives:
for (r, s) in statuses.iteritems():
if s['standby_for_name'] == active:
if not active in failure_groups:
failure_groups[active] = []
log.info('Assigning mds rank {r} to failure group {g}'.format(r=r, g=active))
failure_groups[active].append(r)
manager.wait_for_clean()
for (active, standbys) in failure_groups.iteritems():
weight = 1.0
if 'thrash_weights' in config:
weight = int(config['thrash_weights'].get('mds.{_id}'.format(_id=active), '0.0'))
failure_group = [active]
failure_group.extend(standbys)
thrasher = MDSThrasher(
ctx, manager, config,
logger=log.getChild('mds_thrasher.failure_group.[{a}, {sbs}]'.format(
a=active,
sbs=', '.join(standbys)
)
),
failure_group=failure_group,
weight=weight)
thrasher.start()
thrashers[active] = thrasher
# if thrash_weights isn't specified and we've reached max_thrash,
# we're done
if not 'thrash_weights' in config and len(thrashers) == max_thrashers:
break
try:
log.debug('Yielding')
yield
finally:
log.info('joining mds_thrashers')
for t in thrashers:
log.info('join thrasher for failure group [{fg}]'.format(fg=', '.join(failure_group)))
thrashers[t].stop()
thrashers[t].join()
log.info('done joining')