Handling Multiple Requests in Flask

Handling multiple requests in Flask

Yes, deploy your application on a different WSGI server, see the Flask deployment options documentation.

The server component that comes with Flask is really only meant for when you are developing your application; even though it can be configured to handle concurrent requests with app.run(threaded=True) (as of Flask 1.0 this is the default). The above document lists several options for servers that can handle concurrent requests and are far more robust and tuneable.

How many concurrent requests does a single Flask process receive?

When running the development server - which is what you get by running app.run(), you get a single synchronous process, which means at most 1 request is being processed at a time.

By sticking Gunicorn in front of it in its default configuration and simply increasing the number of --workers, what you get is essentially a number of processes (managed by Gunicorn) that each behave like the app.run() development server. 4 workers == 4 concurrent requests. This is because Gunicorn uses its included sync worker type by default.

It is important to note that Gunicorn also includes asynchronous workers, namely eventlet and gevent (and also tornado, but that's best used with the Tornado framework, it seems). By specifying one of these async workers with the --worker-class flag, what you get is Gunicorn managing a number of async processes, each of which managing its own concurrency. These processes don't use threads, but instead coroutines. Basically, within each process, still only 1 thing can be happening at a time (1 thread), but objects can be 'paused' when they are waiting on external processes to finish (think database queries or waiting on network I/O).

This means, if you're using one of Gunicorn's async workers, each worker can handle many more than a single request at a time. Just how many workers is best depends on the nature of your app, its environment, the hardware it runs on, etc. More details can be found on Gunicorn's design page and notes on how gevent works on its intro page.

Handle multiple request at same time on Flask web app

There is a lot of ways in my point of view

  1. When the server get client request then check if there is already a file.if there is already a file then add timestamp or add something else in the filename so the file will not be overwritten.
  2. Ask the user file name and also add timestamp in the name and save it.
  3. You can also use databases to store data of different clients .may be you can create login system and give every user an id and store data for every user in database accordingly.

So on...

You can see there is a lot of ways to solve this.

how does flask handle simultaneous requests?

Flask doesn't. Parallel request handling is the task of the underlying WSGI web server, which sends the requests to Flask for handling.

Flask's built-in development server which is invoked with Flask.run() runs with threads by default

In production, you'd use one of the WSGI containers or other deployment options, and you control parallelism there. Gunicorn, for example, has the -w command line argument which controls the number of worker processes, and -k which controls how these workers work (processes, threads, or a Tornado event machine, among others).

how to handlde multiple concurrent request in flask

You will need to set app.run(threaded=True)) in order to make your Flask application capable of handling multiple concurrent requests.

You may also like to go through the URL - http://flask.pocoo.org/docs/1.0/tutorial/deploy/.



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