class ShardState(db.Model):
"""Single shard execution state.
The shard state is stored in the datastore and is later aggregated by
controller task. ShardState key_name is equal to shard_id.
Shard state contains critical state to ensure the correctness of
shard execution. It is the single source of truth about a shard's
progress. For example:
1. A slice is allowed to run only if its payload matches shard state's
expectation.
2. A slice is considered running only if it has acquired the shard's lock.
3. A slice is considered done only if it has successfully committed shard
state to db.
Properties about the shard:
active: if we have this shard still running as boolean.
counters_map: shard's counters map as CountersMap. All counters yielded
within mapreduce are stored here.
mapreduce_id: unique id of the mapreduce.
shard_id: unique id of this shard as string.
shard_number: ordered number for this shard.
retries: the number of times this shard has been retried.
result_status: If not None, the final status of this shard.
update_time: The last time this shard state was updated.
shard_description: A string description of the work this shard will do.
last_work_item: A string description of the last work item processed.
writer_state: writer state for this shard. The shard's output writer
instance can save in-memory output references to this field in its
"finalize" method.
Properties about slice management:
slice_id: slice id of current executing slice. A slice's task
will not run unless its slice_id matches this. Initial
value is 0. By the end of slice execution, this number is
incremented by 1.
slice_start_time: a slice updates this to now at the beginning of
execution. If the transaction succeeds, the current task holds
a lease of slice duration + some grace period. During this time, no
other task with the same slice_id will execute. Upon slice failure,
the task should try to unset this value to allow retries to carry on
ASAP.
slice_request_id: the request id that holds/held the lease. When lease has
expired, new request needs to verify that said request has indeed
ended according to logs API. Do this only when lease has expired
because logs API is expensive. This field should always be set/unset
with slice_start_time. It is possible Logs API doesn't log a request
at all or doesn't log the end of a request. So a new request can
proceed after a long conservative timeout.
slice_retries: the number of times a slice has been retried due to
processing data when lock is held. Taskqueue/datastore errors
related to slice/shard management are not counted. This count is
only a lower bound and is used to determined when to fail a slice
completely.
acquired_once: whether the lock for this slice has been acquired at
least once. When this is True, duplicates in outputs are possible.
"""
RESULT_SUCCESS = "success"
RESULT_FAILED = "failed"
RESULT_ABORTED = "aborted"
_RESULTS = frozenset([RESULT_SUCCESS, RESULT_FAILED, RESULT_ABORTED])
_MAX_STATES_IN_MEMORY = 10
mapreduce_id = db.StringProperty(required=True)
active = db.BooleanProperty(default=True, indexed=False)
counters_map = json_util.JsonProperty(CountersMap,
default=CountersMap(),
indexed=False)
result_status = db.StringProperty(choices=_RESULTS, indexed=False)
retries = db.IntegerProperty(default=0, indexed=False)
writer_state = json_util.JsonProperty(dict, indexed=False)
slice_id = db.IntegerProperty(default=0, indexed=False)
slice_start_time = db.DateTimeProperty(indexed=False)
slice_request_id = db.ByteStringProperty(indexed=False)
slice_retries = db.IntegerProperty(default=0, indexed=False)
acquired_once = db.BooleanProperty(default=False, indexed=False)
update_time = db.DateTimeProperty(auto_now=True, indexed=False)
shard_description = db.TextProperty(default="")
last_work_item = db.TextProperty(default="")
def __str__(self):
kv = {
"active": self.active,
"slice_id": self.slice_id,
"last_work_item": self.last_work_item,
"update_time": self.update_time
}
if self.result_status:
kv["result_status"] = self.result_status
if self.retries:
kv["retries"] = self.retries
if self.slice_start_time:
kv["slice_start_time"] = self.slice_start_time
if self.slice_retries:
kv["slice_retries"] = self.slice_retries
if self.slice_request_id:
kv["slice_request_id"] = self.slice_request_id
if self.acquired_once:
kv["acquired_once"] = self.acquired_once
keys = kv.keys()
keys.sort()
result = "ShardState is {"
for k in keys:
result += k + ":" + str(kv[k]) + ","
result += "}"
return result
def reset_for_retry(self):
"""Reset self for shard retry."""
self.retries += 1
self.last_work_item = ""
self.active = True
self.result_status = None
self.counters_map = CountersMap()
self.slice_id = 0
self.slice_start_time = None
self.slice_request_id = None
self.slice_retries = 0
self.acquired_once = False
def advance_for_next_slice(self, recovery_slice=False):
"""Advance self for next slice.
Args:
recovery_slice: True if this slice is running recovery logic.
See handlers.MapperWorkerCallbackHandler._attempt_slice_recovery
for more info.
"""
self.slice_start_time = None
self.slice_request_id = None
self.slice_retries = 0
self.acquired_once = False
if recovery_slice:
self.slice_id += 2
else:
self.slice_id += 1
def set_for_failure(self):
self.active = False
self.result_status = self.RESULT_FAILED
def set_for_abort(self):
self.active = False
self.result_status = self.RESULT_ABORTED
def set_for_success(self):
self.active = False
self.result_status = self.RESULT_SUCCESS
self.slice_start_time = None
self.slice_request_id = None
self.slice_retries = 0
self.acquired_once = False
def copy_from(self, other_state):
"""Copy data from another shard state entity to self."""
for prop in self.properties().values():
setattr(self, prop.name, getattr(other_state, prop.name))
def __eq__(self, other):
if not isinstance(other, self.__class__):
return False
return self.properties() == other.properties()
def get_shard_number(self):
"""Gets the shard number from the key name."""
return int(self.key().name().split("-")[-1])
shard_number = property(get_shard_number)
def get_shard_id(self):
"""Returns the shard ID."""
return self.key().name()
shard_id = property(get_shard_id)
@classmethod
def kind(cls):
"""Returns entity kind."""
return "_GAE_MR_ShardState"
@classmethod
def shard_id_from_number(cls, mapreduce_id, shard_number):
"""Get shard id by mapreduce id and shard number.
Args:
mapreduce_id: mapreduce id as string.
shard_number: shard number to compute id for as int.
Returns:
shard id as string.
"""
return "%s-%d" % (mapreduce_id, shard_number)
@classmethod
def get_key_by_shard_id(cls, shard_id):
"""Retrieves the Key for this ShardState.
Args:
shard_id: The shard ID to fetch.
Returns:
The Datatore key to use to retrieve this ShardState.
"""
return db.Key.from_path(cls.kind(), shard_id)
@classmethod
def get_by_shard_id(cls, shard_id):
"""Get shard state from datastore by shard_id.
Args:
shard_id: shard id as string.
Returns:
ShardState for given shard id or None if it's not found.
"""
return cls.get_by_key_name(shard_id)
@classmethod
def find_by_mapreduce_state(cls, mapreduce_state):
"""Find all shard states for given mapreduce.
Deprecated. Use find_all_by_mapreduce_state.
This will be removed after 1.8.9 release.
Args:
mapreduce_state: MapreduceState instance
Returns:
A list of ShardStates.
"""
return list(cls.find_all_by_mapreduce_state(mapreduce_state))
@classmethod
def find_all_by_mapreduce_state(cls, mapreduce_state):
"""Find all shard states for given mapreduce.
Never runs within a transaction since it may touch >5 entity groups (one
for each shard).
Args:
mapreduce_state: MapreduceState instance
Yields:
shard states sorted by shard id.
"""
keys = cls.calculate_keys_by_mapreduce_state(mapreduce_state)
i = 0
while i < len(keys):
@db.non_transactional
def no_tx_get(i):
return db.get(keys[i:i + cls._MAX_STATES_IN_MEMORY])
states = no_tx_get(i)
for s in states:
i += 1
if s is not None:
yield s
@classmethod
def calculate_keys_by_mapreduce_state(cls, mapreduce_state):
"""Calculate all shard states keys for given mapreduce.
Args:
mapreduce_state: MapreduceState instance
Returns:
A list of keys for shard states, sorted by shard id.
The corresponding shard states may not exist.
"""
if mapreduce_state is None:
return []
keys = []
for i in range(mapreduce_state.mapreduce_spec.mapper.shard_count):
shard_id = cls.shard_id_from_number(mapreduce_state.key().name(),
i)
keys.append(cls.get_key_by_shard_id(shard_id))
return keys
@classmethod
def create_new(cls, mapreduce_id, shard_number):
"""Create new shard state.
Args:
mapreduce_id: unique mapreduce id as string.
shard_number: shard number for which to create shard state.
Returns:
new instance of ShardState ready to put into datastore.
"""
shard_id = cls.shard_id_from_number(mapreduce_id, shard_number)
state = cls(key_name=shard_id, mapreduce_id=mapreduce_id)
return state
class MapreduceState(db.Model):
"""Holds accumulated state of mapreduce execution.
MapreduceState is stored in datastore with a key name equal to the
mapreduce ID. Only controller tasks can write to MapreduceState.
Properties:
mapreduce_spec: cached deserialized MapreduceSpec instance. read-only
active: if this MR is still running.
last_poll_time: last time controller job has polled this mapreduce.
counters_map: shard's counters map as CountersMap. Mirrors
counters_map_json.
chart_url: last computed mapreduce status chart url. This chart displays the
progress of all the shards the best way it can.
sparkline_url: last computed mapreduce status chart url in small format.
result_status: If not None, the final status of the job.
active_shards: How many shards are still processing. This starts as 0,
then set by KickOffJob handler to be the actual number of input
readers after input splitting, and is updated by Controller task
as shards finish.
start_time: When the job started.
writer_state: Json property to be used by writer to store its state.
This is filled when single output per job. Will be deprecated.
Use OutputWriter.get_filenames instead.
"""
RESULT_SUCCESS = "success"
RESULT_FAILED = "failed"
RESULT_ABORTED = "aborted"
_RESULTS = frozenset([RESULT_SUCCESS, RESULT_FAILED, RESULT_ABORTED])
mapreduce_spec = json_util.JsonProperty(MapreduceSpec, indexed=False)
active = db.BooleanProperty(default=True, indexed=False)
last_poll_time = db.DateTimeProperty(required=True)
counters_map = json_util.JsonProperty(CountersMap,
default=CountersMap(),
indexed=False)
app_id = db.StringProperty(required=False, indexed=True)
writer_state = json_util.JsonProperty(dict, indexed=False)
active_shards = db.IntegerProperty(default=0, indexed=False)
failed_shards = db.IntegerProperty(default=0, indexed=False)
aborted_shards = db.IntegerProperty(default=0, indexed=False)
result_status = db.StringProperty(required=False, choices=_RESULTS)
chart_url = db.TextProperty(default="")
chart_width = db.IntegerProperty(default=300, indexed=False)
sparkline_url = db.TextProperty(default="")
start_time = db.DateTimeProperty(auto_now_add=True)
@classmethod
def kind(cls):
"""Returns entity kind."""
return "_GAE_MR_MapreduceState"
@classmethod
def get_key_by_job_id(cls, mapreduce_id):
"""Retrieves the Key for a Job.
Args:
mapreduce_id: The job to retrieve.
Returns:
Datastore Key that can be used to fetch the MapreduceState.
"""
return db.Key.from_path(cls.kind(), str(mapreduce_id))
@classmethod
def get_by_job_id(cls, mapreduce_id):
"""Retrieves the instance of state for a Job.
Args:
mapreduce_id: The mapreduce job to retrieve.
Returns:
instance of MapreduceState for passed id.
"""
return db.get(cls.get_key_by_job_id(mapreduce_id))
def set_processed_counts(self, shards_processed):
"""Updates a chart url to display processed count for each shard.
Args:
shards_processed: list of integers with number of processed entities in
each shard
"""
chart = google_chart_api.BarChart(shards_processed)
shard_count = len(shards_processed)
if shards_processed:
stride_length = max(1, shard_count / 16)
chart.bottom.labels = []
for x in xrange(shard_count):
if (x % stride_length == 0 or x == shard_count - 1):
chart.bottom.labels.append(x)
else:
chart.bottom.labels.append("")
chart.left.labels = ["0", str(max(shards_processed))]
chart.left.min = 0
self.chart_width = min(700, max(300, shard_count * 20))
self.chart_url = chart.display.Url(self.chart_width, 200)
def get_processed(self):
"""Number of processed entities.
Returns:
The total number of processed entities as int.
"""
return self.counters_map.get(context.COUNTER_MAPPER_CALLS)
processed = property(get_processed)
@staticmethod
def create_new(mapreduce_id=None, gettime=datetime.datetime.now):
"""Create a new MapreduceState.
Args:
mapreduce_id: Mapreduce id as string.
gettime: Used for testing.
"""
if not mapreduce_id:
mapreduce_id = MapreduceState.new_mapreduce_id()
state = MapreduceState(key_name=mapreduce_id, last_poll_time=gettime())
state.set_processed_counts([])
return state
@staticmethod
def new_mapreduce_id():
"""Generate new mapreduce id."""
return _get_descending_key()
def __eq__(self, other):
if not isinstance(other, self.__class__):
return False
return self.properties() == other.properties()