In my admin I have a form allowing to upload a file to fill the DB.
Parsing and filling the DB take a long time, so I'd like to do it asynchronously.
As recommended by several SO users I tried to install python-celery, but I can't manage to do it (I'm on Webfaction).
Is there any simple, easy-to-install alternative?
If webfaction supports cron jobs you can create your own pseudo broker. You could save your long running tasks to the db and in a 'tasks' table, this would allow you to return a response to the user instantaneously. Then there could be a cron that goes through very frequently and looks for uncompleteled tasks and processes them.
I believe this is what django mailer does
https://github.com/jtauber/django-mailer/
https://stackoverflow.com/a/1419640/594589
Try Gearman along with it's python client library
It's very easy to setup and run gearman. Try few examples.
Related
My Django app generates a complex report that can take upto 5 minutes to create. Therefore it runs once a night using a scheduled management command.
That's been ok, except I now want the user to be able to select the date range for the report, which means the report needs to be created while the user waits.
What are my options for running the tast in the background? So far I've found these:
Celery - might work but is complex
django-background-tasks looks like the right tool for the job but hasn't been updated for years, last supported Django is 2.2
The report/background task could be generated by AWS Lambda, basically in a microservice. Django calls the Microservice which can execute the background task then call the Django app back once finished. This is what I did last time but not sure it would work now as I'd need to send the microservice 10mb of data to process.
Use subprocess.popen which someone here said worked for them but other reports say it doesn't work from Django.
EDIT: Looks like Django 3.1 onwards supports ASync views and may be the simple solution for this.
I am building a small financial web app with django. The app requires that the database has a complete history of prices, regardless of whether someone is currently using the app. These prices are freely available online.
The way I am currently handling this is by running simultaneously a separate python script (outside of django) which downloads the price data and records it in the django database using the sqlite3 module.
My plan for deployment is to run the app on an AWS EC2 instance, change the permissions of the folder where the db file resides, and separately run the download script.
Is this a good way to deploy this sort of app? What are the downsides?
Is there a better way to handle the asynchronous downloads and the deployment? (PythonAnywhere?)
You can write the daemon code and follow this approach to push data to DB as soon as you get it from Internet. Since your daemon would be running independently from the Django, you'd need to take care of data synchronisation related issues as well. One possible solution could be to use DateTimeField in your Django model with auto_now_add = True, which will give you idea of time when data was entered in DB. Hope this helps you or someone else looking for similar answer.
I am implementing a feature in a new project and I was wondering what was the optimal solution to it. The feature itself consists of sub functionality as follows: starting a process, stop a process, and checking if the process is running...all these done in a non-blocking way with django. I am trying to avoid stuff like RabbitMQ, etc. I was thinking maybe of using threading or cron.
EDIT: these functionality need to be triggered from a view.
Any comments or suggestions are the most welcomed. Thanks.
You can surely use celery with the database backend instead of RabbitMQ. Personally, for simple tasks I tend to just write a custom mangement command launched from cron, that gets its input from some database table (i.e. Django model) which is populated by Django view(s).
I'm building a simple website with django that requires constant monitoring of text-based data from another website, that's the way it have to be.
How could I run this service on my web-host using django? would I have to start a separate app and run it via SSH, so it updates the database used by django, or are there any easier/better way?
You could use celery to schedule a job that would read data from that other website and do whatever you want with it.
As an alternative to celery, you could also create a cron job that executes a custom django-admin command. That would give you full access to your django install and ORM. The downside is that cron's smallest time resolution is 1 minute, so if you need it to be real-time, you're not going to be able to do that.
If you do need realtime, then creating a python daemon might be a better option.
How to make Django execute something automatically at a particular time.?
For example, my django application has to ftp upload to remote servers at pre defined times. The ftp server addresses, usernames, passwords, time, day and frequency has been defined in a django model.
I want to run a file upload automatically based on the values stored in the model.
One way to do is to write a python script and add it to the crontab. This script runs every minute and keeps an eye on the time values defined in the model.
Other thing that I can roughly think of is maybe django signals. I'm not sure if they can handle this issue. Is there a way to generate signals at predefined times (Haven't read indepth about them yet).
Just for the record - there is also celery which allows to schedule messages for the future dispatch. It's, however, a different beast than cron, as it requires/uses RabbitMQ and is meant for message queues.
I have been thinking about this recently and have found django-cron which seems as though it would do what you want.
Edit: Also if you are not specifically looking for Django based solution, I have recently used scheduler.py, which is a small single file script which works well and is simple to use.
I've had really good experiences with django-chronograph.
You need to set one crontab task: to call the chronograph python management command, which then runs other custom management commands, based on an admin-tweakable schedule
The problem you're describing is best solved using cron, not Django directly. Since it seems that you need to store data about your ftp uploads in your database (using Django to access it for logs or graphs or whatever), you can make a python script that uses Django which runs via cron.
James Bennett wrote a great article on how to do this which you can read in full here: http://www.b-list.org/weblog/2007/sep/22/standalone-django-scripts/
The main gist of it is that, you can write standalone django scripts that cron can launch and run periodically, and these scripts can fully utilize your Django database, models, and anything else they want to. This gives you the flexibility to run whatever code you need and populate your database, while not trying to make Django do something it wasn't meant to do (Django is a web framework, and is event-driven, not time-driven).
Best of luck!