ModelQueue: Task Queue Based on Django Models¶

ModelQueue is an Apache2 licensed task queue based on Django models.

For example, in appname/models.py:

import modelqueue
from django.db import models

class Task(models.Model):
    data = models.TextField()
    status = modelqueue.StatusField(
        # ^-- Just a models.BigIntegerField
        db_index=True,
        # ^-- Index for faster queries.
        default=modelqueue.Status.waiting,
        # ^-- Waiting state is ready to run.
    )

And in appname/management/commands/process_tasks.py:

import modelqueue, time
from django.core.management.base import BaseCommand
from .models import Task

class Command(BaseCommand):

    def handle(self, *args, **options):
        while True:
            task = modelqueue.run(
                Task.objects.all(),
                # ^-- Queryset of models to process.
                'status',
                # ^-- Field name for model queue.
                self.process,
                # ^-- Callable to process model.
            )
            if task is None:
                time.sleep(1)
                # ^-- Bring your own parallelism/concurrency.

    def process(self, report):
        pass  # Process task models.

And in appname/admin.py:

class TaskAdmin(admin.TaskAdmin):
    actions = [*modelqueue.admin_actions('status')]
    # ^-- Change task status in admin.
    list_filter = [
        modelqueue.admin_list_filter('status'),
        # ^-- Filter tasks in admin by queue state.
    ]

    def get_changeform_initial_data(self, request):
        # v-- Automatically fill in status field when adding a new task.
        return {'status': modelqueue.Status.waiting()}

ModelQueue is a hazardous project. It takes a bad idea and makes it easy and effective. You may come to regret using your database as a task queue but it won’t be today!

Testimonials¶

“I didn’t design relational database systems for this.” ~ Edgar Codd

“Well, at least you’re using transactions.” ~ Jim Gray

“You have successfully ignored most of what’s important in queueing theory.” ~ Agner Erlang

Does your company or website use ModelQueue? Send us a message and let us know.

Features¶

Pure-Python
Supports Django’s admin interface
Tasks can be retried, aborted, and canceled
Supports multiple attempts per task
Bring your own parallelism with threading, multiprocessing, or asyncio
Performance matters (add a single 64-bit field to models)
Fully documented
100% test coverage
Years of stress testing in production
Developed on Python 3.10
Compatible with all Django versions
Tested on CPython 3.6, 3.7, 3.8, 3.9, 3.10
Tested on Linux, Mac OS X, and Windows

Quickstart¶

Installing ModelQueue is simple with pip:

$ python -m pip install modelqueue

You can access documentation in the interpreter with Python’s built-in help function:

>>> import modelqueue
>>> help(modelqueue)

User Guide¶

For those wanting more details, this part of the documentation describes introduction, benchmarks, development, and API.

ModelQueue API Reference

Reference and Indices¶

ModelQueue License¶

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.