Madanswer Technologies Interview Questions Data|Agile|DevOPs|Python - Recent questions and answers in Celery

Answered: The GroupResult takes a list of AsyncResult instances and has the following operations.

Sun, 19 Jun 2022 04:45:07 +0000

e) All the options

Answered: (group(add.s(i, i) for i in xrange(10)) | xsum.s())().get() is an example of

Sun, 19 Jun 2022 04:44:41 +0000

a) chain

Answered: Map and star-map differ from group in what ways?

Sun, 19 Jun 2022 04:44:14 +0000

b) only one task message is sent AND the operation is sequential

Answered: Consider a chain res = chain(add.s(4, 4), mul.s(8), mul.s(10))() where add is defined as a+b and mul is defined as a*b. How can we get intermediate parent results

Sun, 19 Jun 2022 04:43:48 +0000

c) res.parent.parent.get()

Answered: To divide an iterable work into pieces, use

Sun, 19 Jun 2022 04:43:14 +0000

b) chunks

Answered: Let i = app.control.inspect() To get a list of reserved tasks, use

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a) i.reserved()

Answered: To add a consumer to a queue named q1, use

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a) app.control.add_consumer(‘q1’, reply=True)

Answered: Let i = app.control.inspect() To get a list of registered tasks, use

Sun, 19 Jun 2022 04:41:53 +0000

a) i.registered()

Answered: What is the default queue in celery

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d) celery

Answered: To list active queues for the worker w1, use

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b) app.control.inspect([‘w1.local’]).active_queues()

Answered: consider a task T. Write a code to execute in 30 seconds from now, but expires after 3 minutes.

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a) T.apply_async(countdown=30, expires=180)

Answered: If we add the following in celery configuration

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d) All the options

Answered: celeri multi stores information about workers.

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b) False

Answered: Celery automatically retries sending messages in the event of a connection failure.

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a) True

Answered: Consider a file tasks.py with:

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b) tasks.add’

Answered: Consider a task T. Write the code to execute in 10 seconds from now, specified using ETA.

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a) T.apply_async(ETA=now + timedelta(seconds=10))

Answered: Celery has the following defined default result states, except _______.

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b) RUNNING

Answered: Consider the following.

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a) Memory address of the object

Answered: Which of the following calling APIs is/are supported by celery task instances?

Sun, 19 Jun 2022 04:36:50 +0000

d) All the options

Answered: If the following configuration is used, which of the following is used for broker and backend?

Sun, 19 Jun 2022 04:36:24 +0000

b) Both broker and backend are RabbitMQ

Answered: If a task raises an exception, we can override it using __________.

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b) result.get(propagate=False)

Answered: If app=celery(), task is created using _______ decorator.

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b) @app.task

Answered: Name the broker in the following.

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b) RabbitMQ

Answered: Using rpc:// result backend, two processes can wait for the same result.

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b) False

Answered: Celery protocol can be implemented in any language.

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a) True

Answered: A client process ___________.

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c) puts work requests into queues and fetches results from the backend

Answered: To run RabbitMQ in the background, use ________.

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c) $ sudo rabbitmq-server -detached

Answered: Celery is a package available in __________.

Sun, 19 Jun 2022 04:32:58 +0000

c) PyPI

Celery is a package available in PyPI

Answered: Celery Interview Multiple Choice Questions and Answers with Explanation

Thu, 16 Jun 2022 03:20:32 +0000

Question#1 Celery is a package available in __________.

a) Pandas

b) NumPy

c) PyPI

d) SciPy

Answer:- PyPI

Question#2 To run RabbitMQ in the background, use ________.

a) $ sudo rabbitmq-server -background

b) $ sudo rabbitmq-server -b

c) $ sudo rabbitmq-server -detached

d) $ sudo rabbitmq-server -attach

Answer:- $ sudo rabbitmq-server -detached

Question#3 A client process ___________.

a) subscribes to task queues to perform work

b) puts work requests into queues

c) puts work requests into queues and fetches results from the backend

d) fetches results from the backend

e) All the options

Answer:- puts work requests into queues and fetches results from the backend

Question#4 Celery protocol can be implemented in any language.

a) True

b) False

Answer:- True

Question#5 Using rpc:// result backend, two processes can wait for the same result.

a) True

b) False

Answer:- False

Question#6 Name the broker in the following.

app = Celery(‘tasks’, broker=’pyamqp://guest@localhost//’).

a) Redis

b) RabbitMQ

c) Amazon SQS

d) None of the options

Answer:- RabbitMQ

Question#7 If app=celery(), task is created using _______ decorator.

a) app

b) @app.task

c) @task.app

d) All the options

Answer:- @app.task

Question#8 If a task raises an exception, we can override it using __________.

a) result.get(propagate=True)

b) result.get(propagate=False)

c) result.get(exception=True)

d) result.get(exception=False)

Answer:- result.get(propagate=False)

Question#9 If the following configuration is used, which of the following is used for broker and backend?

broker_url = ‘pyamqp://’

result_backend = ‘rpc://’.

a) Broker is Redis, backend is RabbitMQ

b) Both broker and backend are RabbitMQ

c) Both broker and backend are Redis

d) Broker is RabbitMQ, backend is Redis

Answer:- Both broker and backend are RabbitMQ

Question#10 Which of the following calling APIs is/are supported by celery task instances?

a) calling

b) delay

c) apply_async

d) All the options

Answer:- All the options

Question#11 Consider the following.

<<< from celery import Celery

<<< app = Celery()

What does app have?

a) Memory address of the object

b) Name of the current main module

c) Name of the app class

d) All the options

Answer:- Memory address of the object

Question#12 Celery has the following defined default result states, except _______.

a) STARTED

b) RUNNING

c) PENDING

d) RETRY

Answer:- RUNNING

Question#13 Consider a task T. Write the code to execute in 10 seconds from now, specified using ETA.

a) T.apply_async(ETA=now + timedelta(seconds=10))

b) T.apply_async(ETA=now + timedelta(10))

c) T.apply_async(eta=now + timedelta(seconds=10))

d) T.apply_async(countdown=10)

Answer:- T.apply_async(ETA=now + timedelta(seconds=10))

Question#14 Consider a file tasks.py with:

@app.task

def add(x, y):

  return x + y

After executing:

from tasks import add

What will be the output of:

<<< add.name

a) error

b) tasks.add’

c) name not defined

d) None of the options

Answer:- tasks.add’

Question#15 Celery automatically retries sending messages in the event of a connection failure.

a) True

b) False

Answer:- True

Question#16 celeri multi stores information about workers.

a) True

b) False

Answer:- False

Question#17 If we add the following in celery configuration

task_annotations = {

  ‘tasks.add’: {‘rate_limit’: ’10/m’}

}

what does it mean

a) mechanism to low prioritize misbehaving queues

b) the task rate limit is set

c) Only 10 tasks of this type can be processed in a minute

d) All the options

Answer:- All the options

Question#18 consider a task T. Write a code to execute in 30 seconds from now, but expires after 3 minutes.

a) T.apply_async(countdown=30, expires=180)

b) T.apply_async(countdown=30, expires=3min)

c) T.apply_async(timedelta(seconds=30), expires=180)

d) T.apply_async(countdown=180, expires=30)

Answer:- T.apply_async(countdown=30, expires=180)

Question#19 To list active queues for the worker w1, use

a) app.control.inspect().active_queues()

b) app.control.inspect([‘w1.local’]).active_queues()

c) both

d) None

Answer:- app.control.inspect([‘w1.local’]).active_queues()

Question#20 What is the default queue in celery

a) Redis

b) default

c) RabbitMQ

d) celery

Answer:- celery

Question#21 Let

i = app.control.inspect()

To get a list of registered tasks, use

a) i.registered()

b) i.active()

c) i.scheduled()

d) i.reserved()

e) All the options

Answer:- i.registered()

Question#22 To add a consumer to a queue named q1, use

a) app.control.add_consumer(‘q1’, reply=True)

b) app.control.add_consumer(‘q1’, reply=False)

c) app.control.add_consumer(‘q1’, reply=True, destination=[‘worker1@gmail.com’])

d) app.control.add_consumer(‘q1’, reply=False, destination=[‘worker1@gmail.com’])

Answer:- app.control.add_consumer(‘q1’, reply=True)

Question#23 Let

i = app.control.inspect()

To get a list of reserved tasks, use

a) i.reserved()

b) i.registered()

c) i.scheduled()

d) i.active()

Answer:- i.reserved()

Question#24 To divide an iterable work into pieces, use

a) starmap

b) chunks

c) piece

d) chord

Answer:- chunks

Question#25 Consider a chain

res = chain(add.s(4, 4), mul.s(8), mul.s(10))()

where add is defined as a+b and mul is defined as a*b. How can we get intermediate parent results

a) res.parent.parent

b) res.parent.get()

c) res.parent.parent.get()

d) All the options

Answer:- res.parent.parent.get()

Question#26 Map and star-map differ from group in what ways?

a) the operation is parallel

b) only one task message is sent AND the operation is sequential

c) only one task message is sent AND the operation is parallel

d) the operation is sequential

e) only one task message is sent

Answer:- only one task message is sent AND the operation is sequential

Question#27 (group(add.s(i, i) for i in xrange(10)) | xsum.s())().get() is an example of

a) chain

b) group

c) chunk

d) chord

Answer:- chain

Question#28 The GroupResult takes a list of AsyncResult instances and has the following operations.

a) join()

b) revoke()

c) ready()

d) successful()

e) All the options

Answer:- All the options

Celery Interview Question-Answer Part – 2

Write a Commenton Celery Interview Question-Answer Part – 2

Question#1 consider

@app.task

def xsum(numbers):

  return sum(numbers)

What is the map equivalent of

@app.task

def

temp():

  return [xsum(range(10)), xsum(range(100))]

Assume all needed methods are imported

a) ~xsum.map([range(100), range(100)])

b) ~xsum.map([range(100), range(10)])

c) ~xsum.map([range(10), range(100)])

d) ~xsum.map([range(10), range(10)])

Answer:- ~xsum.map([range(10), range(100)])

Question#2 consider a method

def add(a,b):

return a + b

What is a partial signature?

a) s2 = add.s(2)

b) s2 = sum.s(2, 3)

c) s2 = add.s(2, 3)

d) s2 = sum.s(2)

Answer:- s2 = sum.s(2, 3)

Question#3 Consider a chain

res = chain(add.s(4, 4), mul.s(8), mul.s(10))()

where add is defined as a+b and mul is defined as a*b. How can we get intermediate parent results

a) res.parent.parent.get()

b) res.parent.get()

c) res.parent.parent

d) All the options

Answer:- res.parent.get()

Question#4 To ensure a job runs every 15 mins using crontab(), what should be given?

a) crontab(minute=’15’)

b) crontab(minute=’15,30,45′)

c) crontab(minute=’*/15′)

d) crontab(minute=’15,30,45′) AND crontab(minute=’15’)

Answer:- crontab(minute=’*/15′)

Question#5 When using solar scheduling, what is sunrise event?

a) Execute when the upper edge of the sun appears over the eastern horizon in the morning.

b) Execute at the moment after which the sky is no longer completely dark. This is when the sun is 18 degrees below the horizon.

c) Execute when there’s enough sunlight for the horizon and some objects to be distinguishable; formally, when the sun is 12 degrees below the horizon.

d) Execute when there’s enough light for objects to be distinguishable so that outdoor activities can commence; formally, when the Sun is 6 degrees below the horizon.

Answer:- Execute when the upper edge of the sun appears over the eastern horizon in the morning.

Question#6 Solar events are

a) sunset

b) sunrise

c) dawn

d) dusk

e) All the options

Answer:- All the options

Question#7 To start celery beat service using a custom file is achieved using

a) celery -A proj beat /home/celery/var/run/celerybeat-schedule

b) celery -A proj beat -s /home/celery/var/run/celerybeat-schedule

c) celery -A proj beat -file /home/celery/var/run/celerybeat-schedule

d) celery -A proj beat -f /home/celery/var/run/celerybeat-schedule

Answer:- celery -A proj beat -s /home/celery/var/run/celerybeat-schedule

Question#8 What does the command do

$ celery -A proj inspect query_task id1 id2 … idN

a) show the corresponding queues

b) show the task status of id1 id2 … idN

c) show the workers for the corresponding tasks

d) query information about multiple tasks

Answer:- query information about multiple tasks

Question#9 Worker-hearbeat events are sent every

a) 2 min

b) 1 min

c) 4 min

d) 3 min

Answer:- 1 min

Question#10 Following command gives

$ rabbitmqctl list_queues name memory

a) command not found error

b) amount of memory allocated to queue

c) command options incorrect error

d) number of workers currently consuming from a queue named memory

Answer:- command not found error

Question#11 Django database scheduler can detect timezone changes and automatically reset schedule.

a) True

b) False

Answer:- False

Question#12 What does the command do

$ celery -A proj purge -X celery

a) Purge messages from the celery queue

b) Purge messages from all configured task queues

c) Purge messages from all queues other than celery queue

d) None of the options

Answer:- Purge messages from all queues other than celery queue

Question#13 To process events in real time you need

a) State

b) A set of handlers

c) An event consumer

d) All the options

Answer:- All the options

Question#14 What dependencies does celery have?

a) billiard

b) pytz

c) kombu

d) All the options

Answer:- All the options

Question#15 If app=celery(), task is created using _____ decorator?

a) @task.app

b) app

c) @app.task

d) All the options

Answer:- @app.task

Question#16 To configure a database backend as a result backend, the configuration is

result_backend = ‘db+scheme://user:password@host:port/dbname’

Which databases are supported?

a) mysql and postgresql

b) mysql

c) postgresql

d) oracle

e) All the options

Answer:- All the options

Question#17 consider

app = Celery(‘tasks’, broker=’redis://guest@localhost//’)

Name the broker.

a) Amazon SQS

b) Redis

c) RabbitMQ

d) None of the options

Answer:- Redis

Question#18 What brokers does celery support?

a) RabbitMQ, Oracle Message Broker, IBM Websphere

b) RabbitMQ, Redis, Oracle Message Broker

c) RabbitMQ, Redis, Amazon SQS

d) Oracle Message Broker, IBM Websphere, Redis

Answer:- RabbitMQ, Redis, Amazon SQS

Question#19 heartbeat_sent, worker_init and celeryd_init are ____ signals

a) beat

b) worker

c) eventlet

d) task

Answer:- worker

Question#20 Which are the features of celery

a) time & rate limts

b) Scheduling

c) work-flows

d) Monitoring

e) All the options

Answer:- All the options

Question#21 Celery supports the following serialization

a) pickle

b) YAML

c) JSON

d) msgpack

e) All the options

Answer:- All the options

Question#22 Queues created by celery are ____ by default

a) transient

b) persistent

c) none

d) both

Answer:- persistent

Question#23 Celery uses headers to store the content type of the message and its content encoding.

a) True

b) False

Answer:- True

Question#24 Broadcast routing delivers copies of all tasks to all workers connected to a queue.

a) True

b) False

Answer:- True

Question#25 If no custom application has been initiated, celery always creates a special app. It is called

a) app

b) default

c) special

d) celery

Answer:- celery

Question#26 $ celery -A proj control enable_events

is used to

a) add control events

b) dump events

c) disable event messages

d) enable event messages

Answer:- enable event messages

Question#27 To create a queue not defined on task_queues, use

a) task_create_missing_queue

b) task_create_missing_queues

c) task_create_queues

d) task_create_queue

Answer:- task_create_missing_queues

Question#28 A client sending messages is a

a) consumer

b) publisher

c) Broker is RabbitMQ, backend is Redis

d) None of the options

Answer:- Broker is RabbitMQ, backend is Redis

Question#29 Creating a celery instance will do the following

a) Create a logical clock instance, used for events

b) Create the task registry

c) Set itself as the current app

d) Call the app.on_init() callback

e) All the options

Answer:- All the options