# Falsk use celery background tasks
1. Basic environment to build
doc:https://flask.palletsprojects.com/en/1.0.x/patterns/celery/
mkdir celery_tasks
the init .py # instantiated celery
from celery import Celery # celery my_celery = Celery('my_celery')
task_1.py # celery task
from celery_tasks import my_celery @my_celery.task def add_together(a, b): #print('add_together执行中。。。') return a + b
app .__ init__ # celery instance configuration
from .app import create_app, db
from .app import create_app, db
flask_app = create_app()
from celery_tasks import my_celery
from .app import _handle_celery_task
_handle_celery_task(flask_app, my_celery)
Configuration located app.app.py
def _handle_celery_task(app, my_celery): # celery my_celery.conf['broker_url'] = 'redis://:[email protected]:6379/0' my_celery.conf['result_backend'] = 'redis://:[email protected]:6379/0' my_celery.conf['imports'] = ['celery_tasks.tasks_1'] from celery.task import Task class ContextTask(Task): def on_success(self, retval, task_id, args, kwargs): print('task done: {0}'.format(retval)) return super(ContextTask, self).on_success(retval, task_id, args, kwargs) def on_failure(self, exc, task_id, args, kwargs, einfo): print('task fail, reason: {0}'.format(exc)) return super(ContextTask, self).on_failure(exc, task_id, args, kwargs,einfo) def __call__(self, *args, **kwargs): print('应用名:', app.name) with app.app_context(): print(app.route) return self.run(*args, **kwargs) my_celery.Task = ContextTask
2. With a background task status updates
task
@celery.task(bind=True) def long_task(self): """Background task that runs a long function with progress reports.""" verb = ['Starting up', 'Booting', 'Repairing', 'Loading', 'Checking'] adjective = ['master', 'radiant', 'silent', 'harmonic', 'fast'] noun = ['solar array', 'particle reshaper', 'cosmic ray', 'orbiter', 'bit'] message = '' total = random.randint(10, 50) for i in range(total): if not message or random.random() < 0.25: message = '{0} {1} {2}...'.format(random.choice(verb), random.choice(adjective), random.choice(noun)) self.update_state(state='PROGRESS', meta={'current': i, 'total': total, 'status': message}) time.sleep(1) return {'current': 100, 'total': 100, 'status': 'Task completed!', 'result': 42}
route
@app.route('/celery_1', methods=['GET', 'POST']) def celery_1(): if request.method == 'GET': return render_template('celery_t.html') @app.route('/longtask', methods=['POST']) def longtask(): task = long_task.apply_async() return jsonify({}), 202, {'Location': url_for('taskstatus', task_id=task.id)} @app.route('/status/') def taskstatus(task_id): task = long_task.AsyncResult(task_id) if task.state == 'PENDING': # job did not start yet response = { 'state': task.state, 'current': 0, 'total': 1, 'status': 'Pending...' } elif task.state != 'FAILURE': response = { 'state': task.state, 'current': task.info.get('current', 0), 'total': task.info.get('total', 1), 'status': task.info.get('status', '') } if 'result' in task.info: response['result'] = task.info['result'] else: # something went wrong in the background job response = { 'state': task.state, 'current': 1, 'total': 1, 'status': str(task.info), # this is the exception raised } return jsonify(response)
celery_1.html
Code segment is too long, is not the focus of this article, link address:
https://github.com/miguelgrinberg/flask-celery-example
is simply non-stop access / status via ajax /
3. Run
(Venv)> celery -A -l App worker info -P eventlet
--logfile = c.log
Note that the command must be a module pointed configuration example where the Celery, otherwise it will give a null register task celery .
可以看到tasks列表
[tasks]
. app.app.ContextTask
. celery_tasks.tasks_1.add_togethe
. celery_tasks.tasks_1.long_task
Then run flask, access to the appropriate address can verify the effect.