Flask with Celery - workers exit with exitcode1
<p>I have a flask app with celery. <br> 
When I am running the worker as follows:</p>

<pre><code>celery -A app.celery worker
</code></pre>

<p>I get the following output</p>

<pre><code> -------------- celery@local-pc v3.1.22 (Cipater)
---- **** -----
--- * ***  * -- Windows-7-6.1.7601-SP1
-- * - **** ---
- ** ---------- [config]
- ** ---------- .&gt; app:         app:0x483e668
- ** ---------- .&gt; transport:   mongodb://localhost:27017/app
- ** ---------- .&gt; results:     mongodb://localhost:27017/app
- *** --- * --- .&gt; concurrency: 8 (prefork)
-- ******* ----
--- ***** ----- [queues]
 -------------- .&gt; celery           exchange=celery(direct) key=celery


[2016-03-08 15:52:05,587: WARNING/MainProcess] celery@local-pc ready.
[2016-03-08 15:52:08,855: ERROR/MainProcess] Process 'Worker-8' pid:9720 exited with 'exitcode 1'
[2016-03-08 15:52:08,855: ERROR/MainProcess] Process 'Worker-7' pid:11940 exited with 'exitcode 1'
[2016-03-08 15:52:08,856: ERROR/MainProcess] Process 'Worker-6' pid:13120 exited with 'exitcode 1'
...
</code></pre>

<p>It goes endlessly and the CPU raises to 100%.</p>

<p>the relevant configuration is:</p>

<pre><code>CELERY_BROKER_URL = 'mongodb://localhost:27017/app'
CELERY_RESULT_BACKEND = 'mongodb://localhost:27017/'
CELERY_MONGODB_BACKEND_SETTINGS = {
    'database': 'app',
    'taskmeta_collection': 'my_taskmeta_collection',
}
CELERY_IMPORTS = ('app.tasks', )
CELERYD_FORCE_EXEC = True
CELERY_ACCEPT_CONTENT = ['json']
CELERY_TASK_SERIALIZER = 'json'
CELERY_RESULT_SERIALIZER = 'json'
</code></pre>

<p>my project structure is:</p>

<pre><code>proj/
    config.py
    app/
        __init__.py
        tasks.py
        views.py
</code></pre>

<p>this is how I configured my celery in ___init___.py":</p>

<pre><code>app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)


def make_celery(app):
    celery = Celery(app.import_name, broker=app.config['CELERY_BROKER_URL'])
    celery.conf.update(app.config)
    TaskBase = celery.Task

    class ContextTask(TaskBase):
        abstract = True

        def __call__(self, *args, **kwargs):
            with app.app_context():
                return TaskBase.__call__(self, *args, **kwargs)
    celery.Task = ContextTask
    return celery

celery = make_celery(app)
</code></pre>

<p>this is what I have in <code>tasks.py</code></p>

<pre><code>from app import celery


@celery.task()
def add_together(a, b):
    return a + b
</code></pre>

<p><strong>update</strong> </p>

<p>When I remove the following line from the config file the worker does not exit</p>

<pre><code>CELERY_IMPORTS = ('app.tasks', )
</code></pre>

<p>but I get the following error</p>

<pre><code>Traceback (most recent call last):
  File "d:\python34\lib\site-packages\celery\worker\consumer.py", line 456, in on_task_received
    strategies[name](message, body,
KeyError: 'app.tasks.add_together'
</code></pre>