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# -*- coding: utf-8 -*-
# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import collections
import contextlib
import logging
import os
import random
import sys
import threading
import time
logging.basicConfig(level=logging.ERROR)
top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
os.pardir,
os.pardir))
sys.path.insert(0, top_dir)
from zake import fake_client
from taskflow import exceptions as excp
from taskflow.jobs import backends
from taskflow.utils import threading_utils
# In this example we show how a jobboard can be used to post work for other
# entities to work on. This example creates a set of jobs using one producer
# thread (typically this would be split across many machines) and then having
# other worker threads with their own jobboards select work using a given
# filters [red/blue] and then perform that work (and consuming or abandoning
# the job after it has been completed or failed).
# Things to note:
# - No persistence layer is used (or logbook), just the job details are used
# to determine if a job should be selected by a worker or not.
# - This example runs in a single process (this is expected to be atypical
# but this example shows that it can be done if needed, for testing...)
# - The iterjobs(), claim(), consume()/abandon() worker workflow.
# - The post() producer workflow.
SHARED_CONF = {
'path': "/taskflow/jobs",
'board': 'zookeeper',
}
# How many workers and producers of work will be created (as threads).
PRODUCERS = 3
WORKERS = 5
# How many units of work each producer will create.
PRODUCER_UNITS = 10
# How many units of work are expected to be produced (used so workers can
# know when to stop running and shutdown, typically this would not be a
# a value but we have to limit this example's execution time to be less than
# infinity).
EXPECTED_UNITS = PRODUCER_UNITS * PRODUCERS
# Delay between producing/consuming more work.
WORKER_DELAY, PRODUCER_DELAY = (0.5, 0.5)
# To ensure threads don't trample other threads output.
STDOUT_LOCK = threading.Lock()
def dispatch_work(job):
# This is where the jobs contained work *would* be done
time.sleep(1.0)
def safe_print(name, message, prefix=""):
with STDOUT_LOCK:
if prefix:
print("%s %s: %s" % (prefix, name, message))
else:
print("%s: %s" % (name, message))
def worker(ident, client, consumed):
# Create a personal board (using the same client so that it works in
# the same process) and start looking for jobs on the board that we want
# to perform.
name = "W-%s" % (ident)
safe_print(name, "started")
claimed_jobs = 0
consumed_jobs = 0
abandoned_jobs = 0
with backends.backend(name, SHARED_CONF.copy(), client=client) as board:
while len(consumed) != EXPECTED_UNITS:
favorite_color = random.choice(['blue', 'red'])
for job in board.iterjobs(ensure_fresh=True, only_unclaimed=True):
# See if we should even bother with it...
if job.details.get('color') != favorite_color:
continue
safe_print(name, "'%s' [attempting claim]" % (job))
try:
board.claim(job, name)
claimed_jobs += 1
safe_print(name, "'%s' [claimed]" % (job))
except (excp.NotFound, excp.UnclaimableJob):
safe_print(name, "'%s' [claim unsuccessful]" % (job))
else:
try:
dispatch_work(job)
board.consume(job, name)
safe_print(name, "'%s' [consumed]" % (job))
consumed_jobs += 1
consumed.append(job)
except Exception:
board.abandon(job, name)
abandoned_jobs += 1
safe_print(name, "'%s' [abandoned]" % (job))
time.sleep(WORKER_DELAY)
safe_print(name,
"finished (claimed %s jobs, consumed %s jobs,"
" abandoned %s jobs)" % (claimed_jobs, consumed_jobs,
abandoned_jobs), prefix=">>>")
def producer(ident, client):
# Create a personal board (using the same client so that it works in
# the same process) and start posting jobs on the board that we want
# some entity to perform.
name = "P-%s" % (ident)
safe_print(name, "started")
with backends.backend(name, SHARED_CONF.copy(), client=client) as board:
for i in range(0, PRODUCER_UNITS):
job_name = "%s-%s" % (name, i)
details = {
'color': random.choice(['red', 'blue']),
}
job = board.post(job_name, book=None, details=details)
safe_print(name, "'%s' [posted]" % (job))
time.sleep(PRODUCER_DELAY)
safe_print(name, "finished", prefix=">>>")
def main():
# TODO(harlowja): Hack to make eventlet work right, remove when the
# following is fixed: https://github.com/eventlet/eventlet/issues/230
from taskflow.utils import eventlet_utils as _eu # noqa
try:
import eventlet as _eventlet # noqa
except ImportError:
pass
with contextlib.closing(fake_client.FakeClient()) as c:
created = []
for i in range(0, PRODUCERS):
p = threading_utils.daemon_thread(producer, i + 1, c)
created.append(p)
p.start()
consumed = collections.deque()
for i in range(0, WORKERS):
w = threading_utils.daemon_thread(worker, i + 1, c, consumed)
created.append(w)
w.start()
while created:
t = created.pop()
t.join()
# At the end there should be nothing leftover, let's verify that.
board = backends.fetch('verifier', SHARED_CONF.copy(), client=c)
board.connect()
with contextlib.closing(board):
if board.job_count != 0 or len(consumed) != EXPECTED_UNITS:
return 1
return 0
if __name__ == "__main__":
sys.exit(main())
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