/usr/share/pyshared/gluon/scheduler.py is in python-gluon 2.12.3-1.
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# -*- coding: utf-8 -*-
"""
| This file is part of the web2py Web Framework
| Copyrighted by Massimo Di Pierro <mdipierro@cs.depaul.edu>
| License: LGPLv3 (http://www.gnu.org/licenses/lgpl.html)
Background processes made simple
---------------------------------
"""
USAGE = """
## Example
For any existing app
Create File: app/models/scheduler.py ======
from gluon.scheduler import Scheduler
def demo1(*args,**vars):
print 'you passed args=%s and vars=%s' % (args, vars)
return 'done!'
def demo2():
1/0
scheduler = Scheduler(db,dict(demo1=demo1,demo2=demo2))
## run worker nodes with:
cd web2py
python web2py.py -K myapp
or
python gluon/scheduler.py -u sqlite://storage.sqlite \
-f applications/myapp/databases/ \
-t mytasks.py
(-h for info)
python scheduler.py -h
## schedule jobs using
http://127.0.0.1:8000/myapp/appadmin/insert/db/scheduler_task
## monitor scheduled jobs
http://127.0.0.1:8000/myapp/appadmin/select/db?query=db.scheduler_task.id>0
## view completed jobs
http://127.0.0.1:8000/myapp/appadmin/select/db?query=db.scheduler_run.id>0
## view workers
http://127.0.0.1:8000/myapp/appadmin/select/db?query=db.scheduler_worker.id>0
## To install the scheduler as a permanent daemon on Linux (w/ Upstart), put
## the following into /etc/init/web2py-scheduler.conf:
## (This assumes your web2py instance is installed in <user>'s home directory,
## running as <user>, with app <myapp>, on network interface eth0.)
description "web2py task scheduler"
start on (local-filesystems and net-device-up IFACE=eth0)
stop on shutdown
respawn limit 8 60 # Give up if restart occurs 8 times in 60 seconds.
exec sudo -u <user> python /home/<user>/web2py/web2py.py -K <myapp>
respawn
## You can then start/stop/restart/check status of the daemon with:
sudo start web2py-scheduler
sudo stop web2py-scheduler
sudo restart web2py-scheduler
sudo status web2py-scheduler
"""
import os
import time
import multiprocessing
import sys
import threading
import traceback
import signal
import socket
import datetime
import logging
import optparse
import types
import Queue
path = os.getcwd()
if 'WEB2PY_PATH' not in os.environ:
os.environ['WEB2PY_PATH'] = path
try:
# try external module
from simplejson import loads, dumps
except ImportError:
try:
# try stdlib (Python >= 2.6)
from json import loads, dumps
except:
# fallback to pure-Python module
from gluon.contrib.simplejson import loads, dumps
IDENTIFIER = "%s#%s" % (socket.gethostname(), os.getpid())
logger = logging.getLogger('web2py.scheduler.%s' % IDENTIFIER)
from gluon import DAL, Field, IS_NOT_EMPTY, IS_IN_SET, IS_NOT_IN_DB
from gluon import IS_INT_IN_RANGE, IS_DATETIME, IS_IN_DB
from gluon.utils import web2py_uuid
from gluon.storage import Storage
QUEUED = 'QUEUED'
ASSIGNED = 'ASSIGNED'
RUNNING = 'RUNNING'
COMPLETED = 'COMPLETED'
FAILED = 'FAILED'
TIMEOUT = 'TIMEOUT'
STOPPED = 'STOPPED'
ACTIVE = 'ACTIVE'
TERMINATE = 'TERMINATE'
DISABLED = 'DISABLED'
KILL = 'KILL'
PICK = 'PICK'
STOP_TASK = 'STOP_TASK'
EXPIRED = 'EXPIRED'
SECONDS = 1
HEARTBEAT = 3 * SECONDS
MAXHIBERNATION = 10
CLEAROUT = '!clear!'
CALLABLETYPES = (types.LambdaType, types.FunctionType,
types.BuiltinFunctionType,
types.MethodType, types.BuiltinMethodType)
class Task(object):
"""Defines a "task" object that gets passed from the main thread to the
executor's one
"""
def __init__(self, app, function, timeout, args='[]', vars='{}', **kwargs):
logger.debug(' new task allocated: %s.%s', app, function)
self.app = app
self.function = function
self.timeout = timeout
self.args = args # json
self.vars = vars # json
self.__dict__.update(kwargs)
def __str__(self):
return '<Task: %s>' % self.function
class TaskReport(object):
"""Defines a "task report" object that gets passed from the executor's
thread to the main one
"""
def __init__(self, status, result=None, output=None, tb=None):
logger.debug(' new task report: %s', status)
if tb:
logger.debug(' traceback: %s', tb)
else:
logger.debug(' result: %s', result)
self.status = status
self.result = result
self.output = output
self.tb = tb
def __str__(self):
return '<TaskReport: %s>' % self.status
class JobGraph(object):
"""Experimental: with JobGraph you can specify
dependencies amongs tasks"""
def __init__(self, db, job_name):
self.job_name = job_name or 'job_0'
self.db = db
def add_deps(self, task_parent, task_child):
"""Creates a dependency between task_parent and task_child"""
self.db.scheduler_task_deps.insert(task_parent=task_parent,
task_child=task_child,
job_name=self.job_name)
def validate(self, job_name):
"""Validates if all tasks job_name can be completed, i.e. there
are no mutual dependencies among tasks.
Commits at the end if successfull, or it rollbacks the entire
transaction. Handle with care!"""
db = self.db
sd = db.scheduler_task_deps
if job_name:
q = sd.job_name == job_name
else:
q = sd.id > 0
edges = db(q).select()
nested_dict = {}
for row in edges:
k = row.task_parent
if k in nested_dict:
nested_dict[k].add(row.task_child)
else:
nested_dict[k] = set((row.task_child,))
try:
rtn = []
for k, v in nested_dict.items():
v.discard(k) # Ignore self dependencies
extra_items_in_deps = reduce(set.union, nested_dict.values()) - set(nested_dict.keys())
nested_dict.update(dict((item, set()) for item in extra_items_in_deps))
while True:
ordered = set(item for item, dep in nested_dict.items() if not dep)
if not ordered:
break
rtn.append(ordered)
nested_dict = dict(
(item, (dep - ordered)) for item, dep in nested_dict.items()
if item not in ordered
)
assert not nested_dict, "A cyclic dependency exists amongst %r" % nested_dict
db.commit()
return rtn
except:
db.rollback()
return None
def demo_function(*argv, **kwargs):
""" test function """
for i in range(argv[0]):
print 'click', i
time.sleep(1)
return 'done'
# the two functions below deal with simplejson decoding as unicode, esp for the dict decode
# and subsequent usage as function Keyword arguments unicode variable names won't work!
# borrowed from http://stackoverflow.com/questions/956867/how-to-get-string-objects-instead-unicode-ones-from-json-in-python
def _decode_list(lst):
newlist = []
for i in lst:
if isinstance(i, unicode):
i = i.encode('utf-8')
elif isinstance(i, list):
i = _decode_list(i)
newlist.append(i)
return newlist
def _decode_dict(dct):
newdict = {}
for k, v in dct.iteritems():
if isinstance(k, unicode):
k = k.encode('utf-8')
if isinstance(v, unicode):
v = v.encode('utf-8')
elif isinstance(v, list):
v = _decode_list(v)
newdict[k] = v
return newdict
def executor(queue, task, out):
"""The function used to execute tasks in the background process"""
logger.debug(' task started')
class LogOutput(object):
"""Facility to log output at intervals"""
def __init__(self, out_queue):
self.out_queue = out_queue
self.stdout = sys.stdout
sys.stdout = self
def __del__(self):
sys.stdout = self.stdout
def flush(self):
pass
def write(self, data):
self.out_queue.put(data)
W2P_TASK = Storage({'id': task.task_id, 'uuid': task.uuid})
stdout = LogOutput(out)
try:
if task.app:
os.chdir(os.environ['WEB2PY_PATH'])
from gluon.shell import env, parse_path_info
from gluon import current
level = logging.getLogger().getEffectiveLevel()
logging.getLogger().setLevel(logging.WARN)
# Get controller-specific subdirectory if task.app is of
# form 'app/controller'
(a, c, f) = parse_path_info(task.app)
_env = env(a=a, c=c, import_models=True)
logging.getLogger().setLevel(level)
f = task.function
functions = current._scheduler.tasks
if not functions:
#look into env
_function = _env.get(f)
else:
_function = functions.get(f)
if not isinstance(_function, CALLABLETYPES):
raise NameError(
"name '%s' not found in scheduler's environment" % f)
# Inject W2P_TASK into environment
_env.update({'W2P_TASK': W2P_TASK})
# Inject W2P_TASK into current
from gluon import current
current.W2P_TASK = W2P_TASK
globals().update(_env)
args = _decode_list(loads(task.args))
vars = loads(task.vars, object_hook=_decode_dict)
result = dumps(_function(*args, **vars))
else:
### for testing purpose only
result = eval(task.function)(
*loads(task.args, object_hook=_decode_dict),
**loads(task.vars, object_hook=_decode_dict))
queue.put(TaskReport('COMPLETED', result=result))
except BaseException, e:
tb = traceback.format_exc()
queue.put(TaskReport('FAILED', tb=tb))
del stdout
class MetaScheduler(threading.Thread):
"""Base class documenting scheduler's base methods"""
def __init__(self):
threading.Thread.__init__(self)
self.process = None # the background process
self.have_heartbeat = True # set to False to kill
self.empty_runs = 0
def async(self, task):
"""Starts the background process
Args:
task : a `Task` object
Returns:
tuple: containing::
('ok',result,output)
('error',exception,None)
('timeout',None,None)
('terminated',None,None)
"""
db = self.db
sr = db.scheduler_run
out = multiprocessing.Queue()
queue = multiprocessing.Queue(maxsize=1)
p = multiprocessing.Process(target=executor, args=(queue, task, out))
self.process = p
logger.debug(' task starting')
p.start()
task_output = ""
tout = ""
try:
if task.sync_output > 0:
run_timeout = task.sync_output
else:
run_timeout = task.timeout
start = time.time()
while p.is_alive() and (not task.timeout or time.time() - start < task.timeout):
if tout:
try:
logger.debug(' partial output saved')
db(sr.id == task.run_id).update(run_output=task_output)
db.commit()
except:
pass
p.join(timeout=run_timeout)
tout = ""
while not out.empty():
tout += out.get()
if tout:
logger.debug(' partial output: "%s"' % str(tout))
if CLEAROUT in tout:
task_output = tout[
tout.rfind(CLEAROUT) + len(CLEAROUT):]
else:
task_output += tout
except:
p.terminate()
p.join()
self.have_heartbeat = False
logger.debug(' task stopped by general exception')
tr = TaskReport(STOPPED)
else:
if p.is_alive():
p.terminate()
logger.debug(' task timeout')
try:
# we try to get a traceback here
tr = queue.get(timeout=2)
tr.status = TIMEOUT
tr.output = task_output
except Queue.Empty:
tr = TaskReport(TIMEOUT)
elif queue.empty():
self.have_heartbeat = False
logger.debug(' task stopped')
tr = TaskReport(STOPPED)
else:
logger.debug(' task completed or failed')
tr = queue.get()
tr.output = task_output
return tr
def die(self):
"""Forces termination of the worker process along with any running
task"""
logger.info('die!')
self.have_heartbeat = False
self.terminate_process()
def give_up(self):
"""Waits for any running task to be executed, then exits the worker
process"""
logger.info('Giving up as soon as possible!')
self.have_heartbeat = False
def terminate_process(self):
"""Terminates any running tasks (internal use only)"""
try:
self.process.terminate()
except:
pass # no process to terminate
def run(self):
"""This is executed by the main thread to send heartbeats"""
counter = 0
while self.have_heartbeat:
self.send_heartbeat(counter)
counter += 1
def start_heartbeats(self):
self.start()
def send_heartbeat(self, counter):
print 'thum'
time.sleep(1)
def pop_task(self):
"""Fetches a task ready to be executed"""
return Task(
app=None,
function='demo_function',
timeout=7,
args='[2]',
vars='{}')
def report_task(self, task, task_report):
"""Creates a task report"""
print 'reporting task'
pass
def sleep(self):
pass
def loop(self):
"""Main loop, fetching tasks and starting executor's background
processes"""
try:
self.start_heartbeats()
while True and self.have_heartbeat:
logger.debug('looping...')
task = self.pop_task()
if task:
self.empty_runs = 0
self.report_task(task, self.async(task))
else:
self.empty_runs += 1
logger.debug('sleeping...')
if self.max_empty_runs != 0:
logger.debug('empty runs %s/%s',
self.empty_runs, self.max_empty_runs)
if self.empty_runs >= self.max_empty_runs:
logger.info(
'empty runs limit reached, killing myself')
self.die()
self.sleep()
except KeyboardInterrupt:
self.die()
TASK_STATUS = (QUEUED, RUNNING, COMPLETED, FAILED, TIMEOUT, STOPPED, EXPIRED)
RUN_STATUS = (RUNNING, COMPLETED, FAILED, TIMEOUT, STOPPED)
WORKER_STATUS = (ACTIVE, PICK, DISABLED, TERMINATE, KILL, STOP_TASK)
class TYPE(object):
"""
Validator that checks whether field is valid json and validates its type.
Used for `args` and `vars` of the scheduler_task table
"""
def __init__(self, myclass=list, parse=False):
self.myclass = myclass
self.parse = parse
def __call__(self, value):
from gluon import current
try:
obj = loads(value)
except:
return (value, current.T('invalid json'))
else:
if isinstance(obj, self.myclass):
if self.parse:
return (obj, None)
else:
return (value, None)
else:
return (value, current.T('Not of type: %s') % self.myclass)
class Scheduler(MetaScheduler):
"""Scheduler object
Args:
db: DAL connection where Scheduler will create its tables
tasks(dict): either a dict containing name-->func or None.
If None, functions will be searched in the environment
migrate(bool): turn migration on/off for the Scheduler's tables
worker_name(str): force worker_name to identify each process.
Leave it to None to autoassign a name (hostname#pid)
group_names(list): process tasks belonging to this group
defaults to ['main'] if nothing gets passed
heartbeat(int): how many seconds the worker sleeps between one
execution and the following one. Indirectly sets how many seconds
will pass between checks for new tasks
max_empty_runs(int): how many loops are allowed to pass without
processing any tasks before exiting the process. 0 to keep always
the process alive
discard_results(bool): Scheduler stores executions's details into the
scheduler_run table. By default, only if there is a result the
details are kept. Turning this to True means discarding results
even for tasks that return something
utc_time(bool): do all datetime calculations assuming UTC as the
timezone. Remember to pass `start_time` and `stop_time` to tasks
accordingly
"""
def __init__(self, db, tasks=None, migrate=True,
worker_name=None, group_names=None, heartbeat=HEARTBEAT,
max_empty_runs=0, discard_results=False, utc_time=False):
MetaScheduler.__init__(self)
self.db = db
self.db_thread = None
self.tasks = tasks
self.group_names = group_names or ['main']
self.heartbeat = heartbeat
self.worker_name = worker_name or IDENTIFIER
self.max_empty_runs = max_empty_runs
self.discard_results = discard_results
self.is_a_ticker = False
self.do_assign_tasks = False
self.greedy = False
self.utc_time = utc_time
self.w_stats = Storage(
dict(
status=RUNNING,
sleep=heartbeat,
total=0,
errors=0,
empty_runs=0,
queue=0,
distribution=None,
workers=0)
) # dict holding statistics
from gluon import current
current._scheduler = self
self.define_tables(db, migrate=migrate)
def __get_migrate(self, tablename, migrate=True):
if migrate is False:
return False
elif migrate is True:
return True
elif isinstance(migrate, str):
return "%s%s.table" % (migrate, tablename)
return True
def now(self):
"""Shortcut that fetches current time based on UTC preferences"""
return self.utc_time and datetime.datetime.utcnow() or datetime.datetime.now()
def set_requirements(self, scheduler_task):
"""Called to set defaults for lazy_tables connections"""
from gluon import current
if hasattr(current, 'request'):
scheduler_task.application_name.default = '%s/%s' % (
current.request.application, current.request.controller
)
def define_tables(self, db, migrate):
"""Defines Scheduler tables structure"""
from pydal.base import DEFAULT
logger.debug('defining tables (migrate=%s)', migrate)
now = self.now
db.define_table(
'scheduler_task',
Field('application_name', requires=IS_NOT_EMPTY(),
default=None, writable=False),
Field('task_name', default=None),
Field('group_name', default='main'),
Field('status', requires=IS_IN_SET(TASK_STATUS),
default=QUEUED, writable=False),
Field('function_name',
requires=IS_IN_SET(sorted(self.tasks.keys()))
if self.tasks else DEFAULT),
Field('uuid', length=255,
requires=IS_NOT_IN_DB(db, 'scheduler_task.uuid'),
unique=True, default=web2py_uuid),
Field('args', 'text', default='[]', requires=TYPE(list)),
Field('vars', 'text', default='{}', requires=TYPE(dict)),
Field('enabled', 'boolean', default=True),
Field('start_time', 'datetime', default=now,
requires=IS_DATETIME()),
Field('next_run_time', 'datetime', default=now),
Field('stop_time', 'datetime'),
Field('repeats', 'integer', default=1, comment="0=unlimited",
requires=IS_INT_IN_RANGE(0, None)),
Field('retry_failed', 'integer', default=0, comment="-1=unlimited",
requires=IS_INT_IN_RANGE(-1, None)),
Field('period', 'integer', default=60, comment='seconds',
requires=IS_INT_IN_RANGE(0, None)),
Field('prevent_drift', 'boolean', default=False,
comment='Cron-like start_times between runs'),
Field('timeout', 'integer', default=60, comment='seconds',
requires=IS_INT_IN_RANGE(1, None)),
Field('sync_output', 'integer', default=0,
comment="update output every n sec: 0=never",
requires=IS_INT_IN_RANGE(0, None)),
Field('times_run', 'integer', default=0, writable=False),
Field('times_failed', 'integer', default=0, writable=False),
Field('last_run_time', 'datetime', writable=False, readable=False),
Field('assigned_worker_name', default='', writable=False),
on_define=self.set_requirements,
migrate=self.__get_migrate('scheduler_task', migrate),
format='%(task_name)s')
db.define_table(
'scheduler_run',
Field('task_id', 'reference scheduler_task'),
Field('status', requires=IS_IN_SET(RUN_STATUS)),
Field('start_time', 'datetime'),
Field('stop_time', 'datetime'),
Field('run_output', 'text'),
Field('run_result', 'text'),
Field('traceback', 'text'),
Field('worker_name', default=self.worker_name),
migrate=self.__get_migrate('scheduler_run', migrate)
)
db.define_table(
'scheduler_worker',
Field('worker_name', length=255, unique=True),
Field('first_heartbeat', 'datetime'),
Field('last_heartbeat', 'datetime'),
Field('status', requires=IS_IN_SET(WORKER_STATUS)),
Field('is_ticker', 'boolean', default=False, writable=False),
Field('group_names', 'list:string', default=self.group_names),
Field('worker_stats', 'json'),
migrate=self.__get_migrate('scheduler_worker', migrate)
)
db.define_table(
'scheduler_task_deps',
Field('job_name', default='job_0'),
Field('task_parent', 'integer',
requires=IS_IN_DB(db, 'scheduler_task.id',
'%(task_name)s')
),
Field('task_child', 'reference scheduler_task'),
Field('can_visit', 'boolean', default=False),
migrate=self.__get_migrate('scheduler_task_deps', migrate)
)
if migrate is not False:
db.commit()
def loop(self, worker_name=None):
"""Main loop
This works basically as a neverending loop that:
- checks if the worker is ready to process tasks (is not DISABLED)
- pops a task from the queue
- if there is a task:
- spawns the executor background process
- waits for the process to be finished
- sleeps `heartbeat` seconds
- if there is not a task:
- checks for max_empty_runs
- sleeps `heartbeat` seconds
"""
signal.signal(signal.SIGTERM, lambda signum, stack_frame: sys.exit(1))
try:
self.start_heartbeats()
while True and self.have_heartbeat:
if self.w_stats.status == DISABLED:
logger.debug('Someone stopped me, sleeping until better'
' times come (%s)', self.w_stats.sleep)
self.sleep()
continue
logger.debug('looping...')
task = self.wrapped_pop_task()
if task:
self.w_stats.empty_runs = 0
self.w_stats.status = RUNNING
self.w_stats.total += 1
self.wrapped_report_task(task, self.async(task))
if not self.w_stats.status == DISABLED:
self.w_stats.status = ACTIVE
else:
self.w_stats.empty_runs += 1
logger.debug('sleeping...')
if self.max_empty_runs != 0:
logger.debug('empty runs %s/%s',
self.w_stats.empty_runs, self.max_empty_runs)
if self.w_stats.empty_runs >= self.max_empty_runs:
logger.info(
'empty runs limit reached, killing myself')
self.die()
self.sleep()
except (KeyboardInterrupt, SystemExit):
logger.info('catched')
self.die()
def wrapped_assign_tasks(self, db):
"""Commodity function to call `assign_tasks` and trap exceptions
If an exception is raised, assume it happened because of database
contention and retries `assign_task` after 0.5 seconds
"""
logger.debug('Assigning tasks...')
db.commit() # db.commit() only for Mysql
x = 0
while x < 10:
try:
self.assign_tasks(db)
db.commit()
logger.debug('Tasks assigned...')
break
except:
self.w_stats.errors += 1
db.rollback()
logger.error('TICKER: error assigning tasks (%s)', x)
x += 1
time.sleep(0.5)
def wrapped_pop_task(self):
"""Commodity function to call `pop_task` and trap exceptions
If an exception is raised, assume it happened because of database
contention and retries `pop_task` after 0.5 seconds
"""
db = self.db
db.commit() # another nifty db.commit() only for Mysql
x = 0
while x < 10:
try:
rtn = self.pop_task(db)
return rtn
break
except:
self.w_stats.errors += 1
db.rollback()
logger.error(' error popping tasks')
x += 1
time.sleep(0.5)
def pop_task(self, db):
"""Grabs a task ready to be executed from the queue"""
now = self.now()
st = self.db.scheduler_task
if self.is_a_ticker and self.do_assign_tasks:
#I'm a ticker, and 5 loops passed without reassigning tasks,
#let's do that and loop again
self.wrapped_assign_tasks(db)
return None
# ready to process something
grabbed = db(
(st.assigned_worker_name == self.worker_name) &
(st.status == ASSIGNED)
)
task = grabbed.select(limitby=(0, 1), orderby=st.next_run_time).first()
if task:
task.update_record(status=RUNNING, last_run_time=now)
# noone will touch my task!
db.commit()
logger.debug(' work to do %s', task.id)
else:
if self.is_a_ticker and self.greedy:
# there are other tasks ready to be assigned
logger.info('TICKER: greedy loop')
self.wrapped_assign_tasks(db)
else:
logger.info('nothing to do')
return None
times_run = task.times_run + 1
if not task.prevent_drift:
next_run_time = task.last_run_time + datetime.timedelta(
seconds=task.period
)
else:
next_run_time = task.start_time + datetime.timedelta(
seconds=task.period * times_run
)
if times_run < task.repeats or task.repeats == 0:
# need to run (repeating task)
run_again = True
else:
# no need to run again
run_again = False
run_id = 0
while True and not self.discard_results:
logger.debug(' new scheduler_run record')
try:
run_id = db.scheduler_run.insert(
task_id=task.id,
status=RUNNING,
start_time=now,
worker_name=self.worker_name)
db.commit()
break
except:
time.sleep(0.5)
db.rollback()
logger.info('new task %(id)s "%(task_name)s"'
' %(application_name)s.%(function_name)s' % task)
return Task(
app=task.application_name,
function=task.function_name,
timeout=task.timeout,
args=task.args, # in json
vars=task.vars, # in json
task_id=task.id,
run_id=run_id,
run_again=run_again,
next_run_time=next_run_time,
times_run=times_run,
stop_time=task.stop_time,
retry_failed=task.retry_failed,
times_failed=task.times_failed,
sync_output=task.sync_output,
uuid=task.uuid)
def wrapped_report_task(self, task, task_report):
"""Commodity function to call `report_task` and trap exceptions
If an exception is raised, assume it happened because of database
contention and retries `pop_task` after 0.5 seconds
"""
db = self.db
while True:
try:
self.report_task(task, task_report)
db.commit()
break
except:
self.w_stats.errors += 1
db.rollback()
logger.error(' error storing result')
time.sleep(0.5)
def report_task(self, task, task_report):
"""Takes care of storing the result according to preferences
and deals with logic for repeating tasks"""
db = self.db
now = self.now()
st = db.scheduler_task
sr = db.scheduler_run
if not self.discard_results:
if task_report.result != 'null' or task_report.tb:
# result is 'null' as a string if task completed
# if it's stopped it's None as NoneType, so we record
# the STOPPED "run" anyway
logger.debug(' recording task report in db (%s)',
task_report.status)
db(sr.id == task.run_id).update(
status=task_report.status,
stop_time=now,
run_result=task_report.result,
run_output=task_report.output,
traceback=task_report.tb)
else:
logger.debug(' deleting task report in db because of no result')
db(sr.id == task.run_id).delete()
# if there is a stop_time and the following run would exceed it
is_expired = (task.stop_time
and task.next_run_time > task.stop_time
and True or False)
status = (task.run_again and is_expired and EXPIRED
or task.run_again and not is_expired
and QUEUED or COMPLETED)
if task_report.status == COMPLETED:
d = dict(status=status,
next_run_time=task.next_run_time,
times_run=task.times_run,
times_failed=0
)
db(st.id == task.task_id).update(**d)
if status == COMPLETED:
self.update_dependencies(db, task.task_id)
else:
st_mapping = {'FAILED': 'FAILED',
'TIMEOUT': 'TIMEOUT',
'STOPPED': 'QUEUED'}[task_report.status]
status = (task.retry_failed
and task.times_failed < task.retry_failed
and QUEUED or task.retry_failed == -1
and QUEUED or st_mapping)
db(st.id == task.task_id).update(
times_failed=db.scheduler_task.times_failed + 1,
next_run_time=task.next_run_time,
status=status
)
logger.info('task completed (%s)', task_report.status)
def update_dependencies(self, db, task_id):
db(db.scheduler_task_deps.task_child == task_id).update(can_visit=True)
def adj_hibernation(self):
"""Used to increase the "sleep" interval for DISABLED workers"""
if self.w_stats.status == DISABLED:
wk_st = self.w_stats.sleep
hibernation = wk_st + HEARTBEAT if wk_st < MAXHIBERNATION else MAXHIBERNATION
self.w_stats.sleep = hibernation
def send_heartbeat(self, counter):
"""This function is vital for proper coordination among available
workers.
It:
- sends the heartbeat
- elects a ticker among available workers (the only process that
effectively dispatch tasks to workers)
- deals with worker's statuses
- does "housecleaning" for dead workers
- triggers tasks assignment to workers
"""
if not self.db_thread:
logger.debug('thread building own DAL object')
self.db_thread = DAL(
self.db._uri, folder=self.db._adapter.folder)
self.define_tables(self.db_thread, migrate=False)
try:
db = self.db_thread
sw, st = db.scheduler_worker, db.scheduler_task
now = self.now()
# record heartbeat
mybackedstatus = db(sw.worker_name == self.worker_name).select().first()
if not mybackedstatus:
sw.insert(status=ACTIVE, worker_name=self.worker_name,
first_heartbeat=now, last_heartbeat=now,
group_names=self.group_names,
worker_stats=self.w_stats)
self.w_stats.status = ACTIVE
self.w_stats.sleep = self.heartbeat
mybackedstatus = ACTIVE
else:
mybackedstatus = mybackedstatus.status
if mybackedstatus == DISABLED:
# keep sleeping
self.w_stats.status = DISABLED
logger.debug('........recording heartbeat (%s)',
self.w_stats.status)
db(sw.worker_name == self.worker_name).update(
last_heartbeat=now,
worker_stats=self.w_stats)
elif mybackedstatus == TERMINATE:
self.w_stats.status = TERMINATE
logger.debug("Waiting to terminate the current task")
self.give_up()
elif mybackedstatus == KILL:
self.w_stats.status = KILL
self.die()
return
else:
if mybackedstatus == STOP_TASK:
logger.info('Asked to kill the current task')
self.terminate_process()
logger.debug('........recording heartbeat (%s)',
self.w_stats.status)
db(sw.worker_name == self.worker_name).update(
last_heartbeat=now, status=ACTIVE,
worker_stats=self.w_stats)
self.w_stats.sleep = self.heartbeat # re-activating the process
if self.w_stats.status != RUNNING:
self.w_stats.status = ACTIVE
self.do_assign_tasks = False
if counter % 5 == 0 or mybackedstatus == PICK:
try:
# delete dead workers
expiration = now - datetime.timedelta(
seconds=self.heartbeat * 3)
departure = now - datetime.timedelta(
seconds=self.heartbeat * 3 * 15)
logger.debug(
' freeing workers that have not sent heartbeat')
dead_workers = db(
((sw.last_heartbeat < expiration) & (sw.status == ACTIVE)) |
((sw.last_heartbeat < departure) & (sw.status != ACTIVE))
)
dead_workers_name = dead_workers._select(sw.worker_name)
db(
(st.assigned_worker_name.belongs(dead_workers_name)) &
(st.status == RUNNING)
).update(assigned_worker_name='', status=QUEUED)
dead_workers.delete()
try:
self.is_a_ticker = self.being_a_ticker()
except:
logger.error('Error coordinating TICKER')
if self.w_stats.status == ACTIVE:
self.do_assign_tasks = True
except:
logger.error('Error cleaning up')
db.commit()
except:
logger.error('Error retrieving status')
db.rollback()
self.adj_hibernation()
self.sleep()
def being_a_ticker(self):
"""Elects a TICKER process that assigns tasks to available workers.
Does its best to elect a worker that is not busy processing other tasks
to allow a proper distribution of tasks among all active workers ASAP
"""
db = self.db_thread
sw = db.scheduler_worker
my_name = self.worker_name
all_active = db(
(sw.worker_name != my_name) & (sw.status == ACTIVE)
).select(sw.is_ticker, sw.worker_name)
ticker = all_active.find(lambda row: row.is_ticker is True).first()
not_busy = self.w_stats.status == ACTIVE
if not ticker:
# if no other tickers are around
if not_busy:
# only if I'm not busy
db(sw.worker_name == my_name).update(is_ticker=True)
db(sw.worker_name != my_name).update(is_ticker=False)
logger.info("TICKER: I'm a ticker")
else:
# I'm busy
if len(all_active) >= 1:
# so I'll "downgrade" myself to a "poor worker"
db(sw.worker_name == my_name).update(is_ticker=False)
else:
not_busy = True
db.commit()
return not_busy
else:
logger.info(
"%s is a ticker, I'm a poor worker" % ticker.worker_name)
return False
def assign_tasks(self, db):
"""Assigns task to workers, that can then pop them from the queue
Deals with group_name(s) logic, in order to assign linearly tasks
to available workers for those groups
"""
sw, st, sd = db.scheduler_worker, db.scheduler_task, db.scheduler_task_deps
now = self.now()
all_workers = db(sw.status == ACTIVE).select()
# build workers as dict of groups
wkgroups = {}
for w in all_workers:
if w.worker_stats['status'] == 'RUNNING':
continue
group_names = w.group_names
for gname in group_names:
if gname not in wkgroups:
wkgroups[gname] = dict(
workers=[{'name': w.worker_name, 'c': 0}])
else:
wkgroups[gname]['workers'].append(
{'name': w.worker_name, 'c': 0})
# set queued tasks that expired between "runs" (i.e., you turned off
# the scheduler): then it wasn't expired, but now it is
db(
(st.status.belongs((QUEUED, ASSIGNED))) &
(st.stop_time < now)
).update(status=EXPIRED)
# calculate dependencies
deps_with_no_deps = db(
(sd.can_visit == False) &
(~sd.task_child.belongs(
db(sd.can_visit == False)._select(sd.task_parent)
)
)
)._select(sd.task_child)
no_deps = db(
(st.status.belongs((QUEUED, ASSIGNED))) &
(
(sd.id == None) | (st.id.belongs(deps_with_no_deps))
)
)._select(st.id, distinct=True, left=sd.on(
(st.id == sd.task_parent) &
(sd.can_visit == False)
)
)
all_available = db(
(st.status.belongs((QUEUED, ASSIGNED))) &
((st.times_run < st.repeats) | (st.repeats == 0)) &
(st.start_time <= now) &
((st.stop_time == None) | (st.stop_time > now)) &
(st.next_run_time <= now) &
(st.enabled == True) &
(st.id.belongs(no_deps))
)
limit = len(all_workers) * (50 / (len(wkgroups) or 1))
# if there are a moltitude of tasks, let's figure out a maximum of
# tasks per worker. This can be further tuned with some added
# intelligence (like esteeming how many tasks will a worker complete
# before the ticker reassign them around, but the gain is quite small
# 50 is a sweet spot also for fast tasks, with sane heartbeat values
# NB: ticker reassign tasks every 5 cycles, so if a worker completes its
# 50 tasks in less than heartbeat*5 seconds,
# it won't pick new tasks until heartbeat*5 seconds pass.
# If a worker is currently elaborating a long task, its tasks needs to
# be reassigned to other workers
# this shuffles up things a bit, in order to give a task equal chances
# to be executed
# let's freeze it up
db.commit()
x = 0
for group in wkgroups.keys():
tasks = all_available(st.group_name == group).select(
limitby=(0, limit), orderby = st.next_run_time)
# let's break up the queue evenly among workers
for task in tasks:
x += 1
gname = task.group_name
ws = wkgroups.get(gname)
if ws:
counter = 0
myw = 0
for i, w in enumerate(ws['workers']):
if w['c'] < counter:
myw = i
counter = w['c']
assigned_wn = wkgroups[gname]['workers'][myw]['name']
d = dict(
status=ASSIGNED,
assigned_worker_name=assigned_wn
)
if not task.task_name:
d['task_name'] = task.function_name
db(
(st.id == task.id) &
(st.status.belongs((QUEUED, ASSIGNED)))
).update(**d)
wkgroups[gname]['workers'][myw]['c'] += 1
db.commit()
# I didn't report tasks but I'm working nonetheless!!!!
if x > 0:
self.w_stats.empty_runs = 0
self.w_stats.queue = x
self.w_stats.distribution = wkgroups
self.w_stats.workers = len(all_workers)
# I'll be greedy only if tasks assigned are equal to the limit
# (meaning there could be others ready to be assigned)
self.greedy = x >= limit
logger.info('TICKER: workers are %s', len(all_workers))
logger.info('TICKER: tasks are %s', x)
def sleep(self):
"""Calculates the number of seconds to sleep according to worker's
status and `heartbeat` parameter"""
time.sleep(self.w_stats.sleep)
# should only sleep until next available task
def set_worker_status(self, group_names=None, action=ACTIVE,
exclude=None, limit=None, worker_name=None):
"""Internal function to set worker's status"""
ws = self.db.scheduler_worker
if not group_names:
group_names = self.group_names
elif isinstance(group_names, str):
group_names = [group_names]
if worker_name:
self.db(ws.worker_name == worker_name).update(status=action)
return
exclusion = exclude and exclude.append(action) or [action]
if not limit:
for group in group_names:
self.db(
(ws.group_names.contains(group)) &
(~ws.status.belongs(exclusion))
).update(status=action)
else:
for group in group_names:
workers = self.db((ws.group_names.contains(group)) &
(~ws.status.belongs(exclusion))
)._select(ws.id, limitby=(0, limit))
self.db(ws.id.belongs(workers)).update(status=action)
def disable(self, group_names=None, limit=None, worker_name=None):
"""Sets DISABLED on the workers processing `group_names` tasks.
A DISABLED worker will be kept alive but it won't be able to process
any waiting tasks, essentially putting it to sleep.
By default, all group_names of Scheduler's instantation are selected"""
self.set_worker_status(
group_names=group_names,
action=DISABLED,
exclude=[DISABLED, KILL, TERMINATE],
limit=limit)
def resume(self, group_names=None, limit=None, worker_name=None):
"""Wakes a worker up (it will be able to process queued tasks)"""
self.set_worker_status(
group_names=group_names,
action=ACTIVE,
exclude=[KILL, TERMINATE],
limit=limit)
def terminate(self, group_names=None, limit=None, worker_name=None):
"""Sets TERMINATE as worker status. The worker will wait for any
currently running tasks to be executed and then it will exit gracefully
"""
self.set_worker_status(
group_names=group_names,
action=TERMINATE,
exclude=[KILL],
limit=limit)
def kill(self, group_names=None, limit=None, worker_name=None):
"""Sets KILL as worker status. The worker will be killed even if it's
processing a task."""
self.set_worker_status(
group_names=group_names,
action=KILL,
limit=limit)
def queue_task(self, function, pargs=[], pvars={}, **kwargs):
"""
Queue tasks. This takes care of handling the validation of all
parameters
Args:
function: the function (anything callable with a __name__)
pargs: "raw" args to be passed to the function. Automatically
jsonified.
pvars: "raw" kwargs to be passed to the function. Automatically
jsonified
kwargs: all the parameters available (basically, every
`scheduler_task` column). If args and vars are here, they should
be jsonified already, and they will override pargs and pvars
Returns:
a dict just as a normal validate_and_insert(), plus a uuid key
holding the uuid of the queued task. If validation is not passed
( i.e. some parameters are invalid) both id and uuid will be None,
and you'll get an "error" dict holding the errors found.
"""
if hasattr(function, '__name__'):
function = function.__name__
targs = 'args' in kwargs and kwargs.pop('args') or dumps(pargs)
tvars = 'vars' in kwargs and kwargs.pop('vars') or dumps(pvars)
tuuid = 'uuid' in kwargs and kwargs.pop('uuid') or web2py_uuid()
tname = 'task_name' in kwargs and kwargs.pop('task_name') or function
immediate = 'immediate' in kwargs and kwargs.pop('immediate') or None
rtn = self.db.scheduler_task.validate_and_insert(
function_name=function,
task_name=tname,
args=targs,
vars=tvars,
uuid=tuuid,
**kwargs)
if not rtn.errors:
rtn.uuid = tuuid
if immediate:
self.db(
(self.db.scheduler_worker.is_ticker == True)
).update(status=PICK)
else:
rtn.uuid = None
return rtn
def task_status(self, ref, output=False):
"""
Retrieves task status and optionally the result of the task
Args:
ref: can be
- an integer : lookup will be done by scheduler_task.id
- a string : lookup will be done by scheduler_task.uuid
- a `Query` : lookup as you wish, e.g. ::
db.scheduler_task.task_name == 'test1'
output(bool): if `True`, fetch also the scheduler_run record
Returns:
a single Row object, for the last queued task.
If output == True, returns also the last scheduler_run record.
The scheduler_run record is fetched by a left join, so it can
have all fields == None
"""
from pydal.objects import Query
sr, st = self.db.scheduler_run, self.db.scheduler_task
if isinstance(ref, (int, long)):
q = st.id == ref
elif isinstance(ref, str):
q = st.uuid == ref
elif isinstance(ref, Query):
q = ref
else:
raise SyntaxError(
"You can retrieve results only by id, uuid or Query")
fields = [st.ALL]
left = False
orderby = ~st.id
if output:
fields = st.ALL, sr.ALL
left = sr.on(sr.task_id == st.id)
orderby = ~st.id | ~sr.id
row = self.db(q).select(
*fields,
**dict(orderby=orderby,
left=left,
limitby=(0, 1))
).first()
if row and output:
row.result = row.scheduler_run.run_result and \
loads(row.scheduler_run.run_result,
object_hook=_decode_dict) or None
return row
def stop_task(self, ref):
"""Shortcut for task termination.
If the task is RUNNING it will terminate it, meaning that status
will be set as FAILED.
If the task is QUEUED, its stop_time will be set as to "now",
the enabled flag will be set to False, and the status to STOPPED
Args:
ref: can be
- an integer : lookup will be done by scheduler_task.id
- a string : lookup will be done by scheduler_task.uuid
Returns:
- 1 if task was stopped (meaning an update has been done)
- None if task was not found, or if task was not RUNNING or QUEUED
Note:
Experimental
"""
st, sw = self.db.scheduler_task, self.db.scheduler_worker
if isinstance(ref, (int, long)):
q = st.id == ref
elif isinstance(ref, str):
q = st.uuid == ref
else:
raise SyntaxError(
"You can retrieve results only by id or uuid")
task = self.db(q).select(st.id, st.status, st.assigned_worker_name)
task = task.first()
rtn = None
if not task:
return rtn
if task.status == 'RUNNING':
q = sw.worker_name == task.assigned_worker_name
rtn = self.db(q).update(status=STOP_TASK)
elif task.status == 'QUEUED':
rtn = self.db(q).update(
stop_time=self.now(),
enabled=False,
status=STOPPED)
return rtn
def get_workers(self, only_ticker=False):
""" Returns a dict holding `worker_name : {**columns}`
representing all "registered" workers
only_ticker returns only the workers running as a TICKER,
if there are any
"""
db = self.db
if only_ticker:
workers = db(db.scheduler_worker.is_ticker == True).select()
else:
workers = db(db.scheduler_worker.id > 0).select()
all_workers = {}
for row in workers:
all_workers[row.worker_name] = Storage(
status=row.status,
first_heartbeat=row.first_heartbeat,
last_heartbeat=row.last_heartbeat,
group_names=row.group_names,
is_ticker=row.is_ticker,
worker_stats=row.worker_stats
)
return all_workers
def main():
"""
allows to run worker without python web2py.py .... by simply::
python gluon/scheduler.py
"""
parser = optparse.OptionParser()
parser.add_option(
"-w", "--worker_name", dest="worker_name", default=None,
help="start a worker with name")
parser.add_option(
"-b", "--heartbeat", dest="heartbeat", default=10,
type='int', help="heartbeat time in seconds (default 10)")
parser.add_option(
"-L", "--logger_level", dest="logger_level",
default=30,
type='int',
help="set debug output level (0-100, 0 means all, 100 means none;default is 30)")
parser.add_option("-E", "--empty-runs",
dest="max_empty_runs",
type='int',
default=0,
help="max loops with no grabbed tasks permitted (0 for never check)")
parser.add_option(
"-g", "--group_names", dest="group_names",
default='main',
help="comma separated list of groups to be picked by the worker")
parser.add_option(
"-f", "--db_folder", dest="db_folder",
default='/Users/mdipierro/web2py/applications/scheduler/databases',
help="location of the dal database folder")
parser.add_option(
"-u", "--db_uri", dest="db_uri",
default='sqlite://storage.sqlite',
help="database URI string (web2py DAL syntax)")
parser.add_option(
"-t", "--tasks", dest="tasks", default=None,
help="file containing task files, must define" +
"tasks = {'task_name':(lambda: 'output')} or similar set of tasks")
parser.add_option(
"-U", "--utc-time", dest="utc_time", default=False,
help="work with UTC timestamps"
)
(options, args) = parser.parse_args()
if not options.tasks or not options.db_uri:
print USAGE
if options.tasks:
path, filename = os.path.split(options.tasks)
if filename.endswith('.py'):
filename = filename[:-3]
sys.path.append(path)
print 'importing tasks...'
tasks = __import__(filename, globals(), locals(), [], -1).tasks
print 'tasks found: ' + ', '.join(tasks.keys())
else:
tasks = {}
group_names = [x.strip() for x in options.group_names.split(',')]
logging.getLogger().setLevel(options.logger_level)
print 'groups for this worker: ' + ', '.join(group_names)
print 'connecting to database in folder: ' + options.db_folder or './'
print 'using URI: ' + options.db_uri
db = DAL(options.db_uri, folder=options.db_folder)
print 'instantiating scheduler...'
scheduler = Scheduler(db=db,
worker_name=options.worker_name,
tasks=tasks,
migrate=True,
group_names=group_names,
heartbeat=options.heartbeat,
max_empty_runs=options.max_empty_runs,
utc_time=options.utc_time)
signal.signal(signal.SIGTERM, lambda signum, stack_frame: sys.exit(1))
print 'starting main worker loop...'
scheduler.loop()
if __name__ == '__main__':
main()
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