Commit 81a41da5 authored by Matthew Oliver's avatar Matthew Oliver

Sharding: Clean up old CleaveConext's during audit

There is a sharding edge case where more CleaveContext are generated and
stored in the sharding container DB. If this number get's high enough,
like in the linked bug. If enough CleaveContects build up in the DB then
this can lead to the 503's when attempting to list the container due to
all the `X-Container-Sysmeta-Shard-Context-*` headers.

This patch resolves this by tracking the a CleaveContext's last
modified. And during the sharding audit, any context's that hasn't been
touched after reclaim_age are deleted.

This plus the skip empty ranges patches should improve these handoff
shards.

Change-Id: I1e502c328be16fca5f1cca2186b27a0545fecc16
Closes-Bug: #1843313
parent 5cb53838
......@@ -197,7 +197,8 @@ def find_shrinking_candidates(broker, shrink_threshold, merge_size):
class CleavingContext(object):
def __init__(self, ref, cursor='', max_row=None, cleave_to_row=None,
last_cleave_to_row=None, cleaving_done=False,
misplaced_done=False, ranges_done=0, ranges_todo=0):
misplaced_done=False, ranges_done=0, ranges_todo=0,
last_modified=None):
self.ref = ref
self._cursor = None
self.cursor = cursor
......@@ -208,6 +209,7 @@ class CleavingContext(object):
self.misplaced_done = misplaced_done
self.ranges_done = ranges_done
self.ranges_todo = ranges_todo
self.last_modified = last_modified
def __iter__(self):
yield 'ref', self.ref
......@@ -219,6 +221,7 @@ class CleavingContext(object):
yield 'misplaced_done', self.misplaced_done
yield 'ranges_done', self.ranges_done
yield 'ranges_todo', self.ranges_todo
yield 'last_modified', self.last_modified
def _encode(cls, value):
if value is not None and six.PY2 and isinstance(value, six.text_type):
......@@ -241,6 +244,26 @@ class CleavingContext(object):
def _make_ref(cls, broker):
return broker.get_info()['id']
@classmethod
def load_all(cls, broker):
"""
Returns all cleaving contexts stored in the broker.
:param broker:
:return: list of CleavingContexts
"""
brokers = broker.get_brokers()
sysmeta = brokers[-1].get_sharding_sysmeta()
for key, val in sysmeta.items():
# If the value is of length 0, then the metadata is
# marked for deletion
if key.startswith("Context-") and len(val) > 0:
try:
yield cls(**json.loads(val))
except ValueError:
continue
@classmethod
def load(cls, broker):
"""
......@@ -265,6 +288,7 @@ class CleavingContext(object):
return cls(**data)
def store(self, broker):
self.last_modified = Timestamp.now().internal
broker.set_sharding_sysmeta('Context-' + self.ref,
json.dumps(dict(self)))
......@@ -287,6 +311,11 @@ class CleavingContext(object):
return all((self.misplaced_done, self.cleaving_done,
self.max_row == self.cleave_to_row))
def delete(self, broker):
# These will get reclaimed when `_reclaim_metadata` in
# common/db.py is called.
broker.set_sharding_sysmeta('Context-' + self.ref, '')
DEFAULT_SHARD_CONTAINER_THRESHOLD = 1000000
DEFAULT_SHARD_SHRINK_POINT = 25
......@@ -724,12 +753,23 @@ class ContainerSharder(ContainerReplicator):
self._increment_stat('audit_shard', 'success', statsd=True)
return True
def _audit_cleave_contexts(self, broker):
for context in CleavingContext.load_all(broker):
now = Timestamp.now()
last_mod = context.last_modified
if not last_mod:
context.store(broker)
elif Timestamp(last_mod).timestamp + self.reclaim_age < \
now.timestamp:
context.delete(broker)
def _audit_container(self, broker):
if broker.is_deleted():
# if the container has been marked as deleted, all metadata will
# have been erased so no point auditing. But we want it to pass, in
# case any objects exist inside it.
return True
self._audit_cleave_contexts(broker)
if broker.is_root_container():
return self._audit_root_container(broker)
return self._audit_shard_container(broker)
......@@ -1307,6 +1347,7 @@ class ContainerSharder(ContainerReplicator):
modified_shard_ranges.append(own_shard_range)
broker.merge_shard_ranges(modified_shard_ranges)
if broker.set_sharded_state():
cleaving_context.delete(broker)
return True
else:
self.logger.warning(
......
......@@ -201,6 +201,7 @@ class TestManageShardRanges(unittest.TestCase):
' "cleaving_done": false,',
' "cursor": "",',
' "last_cleave_to_row": null,',
' "last_modified": null,',
' "max_row": -1,',
' "misplaced_done": false,',
' "ranges_done": 0,',
......
......@@ -21,6 +21,7 @@ import os
import shutil
from contextlib import contextmanager
from tempfile import mkdtemp
from uuid import uuid4
import mock
import unittest
......@@ -4486,6 +4487,83 @@ class TestSharder(BaseTestSharder):
set((call[0][0].path, call[0][1]['id'], call[0][2])
for call in mock_process_broker.call_args_list))
def test_audit_cleave_contexts(self):
def add_cleave_context(id, last_modified):
params = {'ref': id,
'cursor': 'curs',
'max_row': 2,
'cleave_to_row': 2,
'last_cleave_to_row': 1,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 2,
'ranges_todo': 4}
if last_modified is not None:
params['last_modified'] = last_modified
key = 'X-Container-Sysmeta-Shard-Context-%s' % id
with mock_timestamp_now(Timestamp(0)):
broker.update_metadata(
{key: (json.dumps(params), Timestamp.now().internal)})
def get_context(id, broker):
data = broker.get_sharding_sysmeta().get('Context-%s' % id)
if data:
return CleavingContext(**json.loads(data))
return data
reclaim_age = 100
broker = self._make_broker()
# sanity check
self.assertIsNone(broker.get_own_shard_range(no_default=True))
self.assertEqual(UNSHARDED, broker.get_db_state())
# Setup some cleaving contexts
id_missing_lm, id_old, id_newish = [str(uuid4()) for _ in range(3)]
contexts = ((id_missing_lm, None),
(id_old, 1),
(id_newish, reclaim_age // 2))
for id, last_modified in contexts:
add_cleave_context(id, last_modified)
with self._mock_sharder({'reclaim_age': str(reclaim_age)}) as sharder:
with mock_timestamp_now(Timestamp(reclaim_age + 2)):
sharder._audit_cleave_contexts(broker)
# now is reclaim_age + 1, so the old should've been removed and the
# context with the missing last modified should now be reclaim + 1
missing_lm_ctx = get_context(id_missing_lm, broker)
self.assertEqual(missing_lm_ctx.last_modified,
Timestamp(reclaim_age + 2).internal)
old_ctx = get_context(id_old, broker)
self.assertEqual(old_ctx, "")
newish_ctx = get_context(id_newish, broker)
self.assertEqual(newish_ctx.ref, id_newish)
# If we push time another reclaim age later, and they all be removed
# minus id_missing_lm as it has a later last_modified.
with self._mock_sharder({'reclaim_age': str(reclaim_age)}) as sharder:
with mock_timestamp_now(Timestamp(reclaim_age * 2)):
sharder._audit_cleave_contexts(broker)
missing_lm_ctx = get_context(id_missing_lm, broker)
self.assertEqual(missing_lm_ctx.last_modified,
Timestamp(reclaim_age + 2).internal)
newish_ctx = get_context(id_newish, broker)
self.assertEqual(newish_ctx, "")
# Fast forward again and they're all cleaned up
with self._mock_sharder({'reclaim_age': str(reclaim_age)}) as sharder:
with mock_timestamp_now(Timestamp(reclaim_age * 3)):
sharder._audit_cleave_contexts(broker)
missing_lm_ctx = get_context(id_missing_lm, broker)
self.assertEqual(missing_lm_ctx, "")
class TestCleavingContext(BaseTestSharder):
def test_init(self):
......@@ -4505,6 +4583,7 @@ class TestCleavingContext(BaseTestSharder):
'max_row': 12,
'cleave_to_row': 11,
'last_cleave_to_row': 10,
'last_modified': None,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 0,
......@@ -4524,6 +4603,7 @@ class TestCleavingContext(BaseTestSharder):
'max_row': 12,
'cleave_to_row': 11,
'last_cleave_to_row': 10,
'last_modified': None,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 0,
......@@ -4571,11 +4651,102 @@ class TestCleavingContext(BaseTestSharder):
self.assertEqual(2, ctx.ranges_done)
self.assertEqual(4, ctx.ranges_todo)
def test_load_all(self):
broker = self._make_broker()
last_ctx = None
db_ids = [str(uuid4()) for _ in range(6)]
for db_id in db_ids:
params = {'ref': db_id,
'cursor': 'curs',
'max_row': 2,
'cleave_to_row': 2,
'last_cleave_to_row': 1,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 2,
'ranges_todo': 4}
key = 'X-Container-Sysmeta-Shard-Context-%s' % db_id
broker.update_metadata(
{key: (json.dumps(params), Timestamp.now().internal)})
for ctx in CleavingContext.load_all(broker):
last_ctx = ctx
self.assertIn(ctx.ref, db_ids)
# If a context is deleted (metadata is "") then it's skipped
last_ctx.delete(broker)
db_ids.remove(last_ctx.ref)
for ctx in CleavingContext.load_all(broker):
self.assertIn(ctx.ref, db_ids)
def test_delete(self):
broker = self._make_broker()
db_id = broker.get_info()['id']
params = {'ref': db_id,
'cursor': 'curs',
'max_row': 2,
'cleave_to_row': 2,
'last_cleave_to_row': 1,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 2,
'ranges_todo': 4}
key = 'X-Container-Sysmeta-Shard-Context-%s' % db_id
broker.update_metadata(
{key: (json.dumps(params), Timestamp.now().internal)})
ctx = CleavingContext.load(broker)
self.assertEqual(db_id, ctx.ref)
# Now let's delete it. When deleted the metadata key will exist, but
# the value will be "" as this means it'll be reaped later.
ctx.delete(broker)
sysmeta = broker.get_sharding_sysmeta()
for key, val in sysmeta.items():
if key == "Context-%s" % db_id:
self.assertEqual(val, "")
break
else:
self.fail("Deleted context 'Context-%s' not found")
def test_last_modified(self):
broker = self._make_broker()
db_id = broker.get_info()['id']
params = {'ref': db_id,
'cursor': 'curs',
'max_row': 2,
'cleave_to_row': 2,
'last_cleave_to_row': 1,
'cleaving_done': False,
'misplaced_done': True,
'ranges_done': 2,
'ranges_todo': 4}
key = 'X-Container-Sysmeta-Shard-Context-%s' % db_id
broker.update_metadata(
{key: (json.dumps(params), Timestamp.now().internal)})
ctx = CleavingContext.load(broker)
self.assertIsNone(ctx.last_modified)
# after a store/save the last_modified will be updated
ctx.store(broker)
ctx = CleavingContext.load(broker)
self.assertIsNotNone(ctx.last_modified)
last_modified = ctx.last_modified
# Store again it'll be updated again
ctx.store(broker)
ctx = CleavingContext.load(broker)
self.assertGreater(ctx.last_modified, last_modified)
def test_store(self):
broker = self._make_sharding_broker()
old_db_id = broker.get_brokers()[0].get_info()['id']
last_mod = Timestamp.now()
ctx = CleavingContext(old_db_id, 'curs', 12, 11, 2, True, True, 2, 4)
ctx.store(broker)
with mock_timestamp_now(last_mod):
ctx.store(broker)
key = 'X-Container-Sysmeta-Shard-Context-%s' % old_db_id
data = json.loads(broker.metadata[key][0])
expected = {'ref': old_db_id,
......@@ -4583,6 +4754,7 @@ class TestCleavingContext(BaseTestSharder):
'max_row': 12,
'cleave_to_row': 11,
'last_cleave_to_row': 2,
'last_modified': last_mod.internal,
'cleaving_done': True,
'misplaced_done': True,
'ranges_done': 2,
......
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