Python flask long running process. If you work with flask have a look at flask-celery.

Python flask long running process These processes are doing some heavy computation (could be even days). Instead, because the code that creates and starts the thread is run after reloading, each cycle creates an additional thread. One common challenge when working with Flask is handling long-running tasks without blocking the main application thread. py app = Fl I need to start a long-running background process with subprocess when someone visits a particular view. Nov 6, 2024 · Explore various techniques to execute a function every hour in your Flask application without relying on cron jobs. However, Flask is primarily designed for synchronous programming, which means that it executes code in a sequential manner. By using Celery, developers can queue these long-running tasks to execute independently from the main app, allowing users to continue interacting without delay. run(), you get a single synchronous process, which means at most 1 request is being processed at a time. In this blog post, we will explore how to convert long-running Kafka consumers into Flask web services. How does Flask handle this? Does it spawn new threads and bounce control around? Jun 12, 2025 · Learn how to run a Flask app with our step-by-step guide. Mar 30, 2024 · Flask is a popular web framework for building Python applications. Though still check your background processes you might have an older version of your server running in the background taking over your python and causing your slow responses. Running Flask in the Background There are a couple of ways one can take to run Flask in the background. While process is running, it saves some partial results into file to work with. 0 this is the default). g. So when user starts new process, I spawn new thread and save thread handle into flask. The script below starts a thread which in t Apr 9, 2024 · Implementing SSE in Python with Flask: Let’s create an end-to-end example that includes a heartbeat function to keep the SSE connection alive while an asynchronous long-running task is running. Flask, Waitress and Javascript used for multiple Server-sent event streams to enable long running jobs web browser auto-refresh 2 days ago · Long-term (infinite) Python processes are essential for tasks like background data processing, web servers, scheduled jobs, or real-time monitoring. In this article, we will demonstrate how to use Python’s threading module to accomplish our task. Aug 26, 2014 · FLASK_DEBUG=1 flask run --no-reload You can use the werkzeug. Dec 14, 2014 · If you need to execute some code after your flask application is started but strictly before the first request, not even be triggered by the execution of the first request as @app. Concept Create separate threads to handle long-running or blocking tasks. route("/") FastAPI Learn Tutorial - User Guide Background Tasks You can define background tasks to be run after returning a response. Flask is easy to get started with and a great way to build websites and web applications. Nov 14, 2024 · Background tasks make your Flask app more efficient by moving long-running tasks outside the main request lifecycle, resulting in a better user experience. Process). Why Use Celery? Asynchronous execution Feb 17, 2025 · Gunicorn (short for Green Unicorn) is a high-performance WSGI server designed for running Python web applications. Never wait for a long running Python task to load a web page. One of my endpoints takes a file uploaded from client and run some analysis. Why, and how to fix? In order to understand why process hangs after 20 minutes much more information needed. This includes, for example: Email notifications sent after performing an action: As Apr 20, 2024 · When developing a Flask application in Python, it is common to use the Ctrl-C keyboard shortcut to stop the application. In this post, I’ll show you how to handle longer running tasks in your API with RQ. before_first_request can handle, you should use Flask_Script, as CESCO said, but you could subclass the class Server and overwrite the __ call __ method, instead of overwriting the runserver command with @manager Mar 25, 2018 · How to properly terminate a flask web application that was launched in a separate thread? I found an incomplete answer that is not clear on how to do it. py Aug 14, 2021 · This short article covers a template for setting up a Flask based web app with a background thread. FileName = ; start. Traditionally The other answers about ThreadPoolExecutor and flask_executor are creating a new thread (or process, as flask_executor is capable of) to execute the "long_running_job". Sep 12, 2024 · This example shows how Celery improves Flask application performance by handling long-running tasks asynchronously, keeping the main application responsive. Jul 23, 2025 · With Python's built-in asyncio, we can introduce asynchronous behavior in Flask applications, allowing tasks like database queries and API requests to run without blocking the main application thread. This way, the system is not blocked by a single process. Write(result); } } I have this python code to execute python from c#. 0's new async functionality and how to leverage it in your Flask projects. To get cool features like separate processes for each request and static file serving, you need to run an actual web service and a WSGI service in front of your Flask application. The long running process is started by a user with super user privile Feb 3, 2013 · Yes, deploy your application on a different WSGI server, see the Flask deployment options documentation. May 28, 2025 · This guide explores running background tasks in Flask, focusing on using Celery, threading, and other techniques, along with best practices and practical applications for building efficient web applications. I decide fork a process How many concurrent requests can Flask manage? And with gunicron? I don't understand it because of single threaded nature of python. Instead of waiting for the command to finish, I wrap it This function can take a long time so I want to display a bootstrap progress bar on the form page indicating how far along in the process the script is. RQ RQ (Redis Queue Jul 30, 2020 · So what I would suggest is that you take the long-running background process out of the Flask views and instead run it in some other way, like a scheduled or an always-on task. is_running_from_reloader function if you wanted to detect when you are in the reloading child process: Nov 16, 2025 · Deploying Python Flask applications to AWS Lambda using Zappa is a popular way to leverage serverless architecture for scalable, cost-effective web services. serving. This calculation take the message input, load more data from a db, then do some processing. Jun 5, 2018 · ProcessStartInfo start = new ProcessStartInfo(); start. StandardOutput) { string result = reader. One common approach to address Oct 20, 2020 · This page gives me a waiting animation but because the process is taking quiet long, I really need a processbar. One thing I want to mention is that this is idle timeout at the TCP level which means that if the connection is Apr 29, 2024 · What is Flask and its ecosystem? Flask is a lightweight and flexible micro web framework for Python. At its core, Flask provides the essentials to build web applications, but it can be extended through a rich ecosystem of extensions that add features such as database integration, form Dec 31, 2011 · I therefore have to delete these files every time a process crashes (a couple of times per week), which sort of defeats the purpose. I added a flash message before that function but the message appears after the function has finished: # main_app. However, when handling long-running tasks (e. However, a common frustration arises when long-running async tasks timeout after 30 seconds—*even if you’ve explicitly set your Lambda function’s timeout to 5 minutes*. Let's say 10,000 jobs running at the same time. However, modern web applications often require handling multiple tasks simultaneously, such as: Making external API calls Processing large datasets Managing real-time communication Asynchronous programming allows us to execute multiple tasks concurrently, improving performance and responsiveness. Using the Werkzeug Server Flask Feb 3, 2022 · To stop a running flask application in the CLI, you can just simply press ctrl + c. Jan 19, 2022 · Objectives By the end of this tutorial, you will be able to: Integrate Redis Queue into a Flask app and create tasks. This tutorial will guide you through the process of optimizing Flask performance with Jan 30, 2013 · However, at the end I want to start a new process (from a python function, currently using multiprocessing. If your request is taking too long Apr 1, 2025 · Tracking progress is essential for long-running operations in Python. g global variable. Feb 25, 2016 · Flask comes with a built-in development web server, but you shouldn't be using it in production. Apr 4, 2023 · Running a Python File in the Background with nohup When running a Python file on the backend, such as a Flask or FastAPI application, it’s often necessary to keep the process running in the background even after the user logs out. Mar 26, 2024 · Learn how to execute long-running tasks asynchronously in Flask using threads, ensuring responsiveness without blocking the main thread. You should not do it. Dec 7, 2021 · from flask import Flask app = Flask(__name__) @app. This is the twenty second installment of the Flask Mega-Tutorial series, in which I'm going to tell you how to create background jobs that run independently of the web server. Jun 16, 2015 · I don't think there is a way to do this using Flask, although you could certainly code your endpoints to allow for them to stop processing (using a database to keep track of these tasks and have the long-running task check that database for the stop flag, for example). Flask is meant to serve APIs and do CRUD. Key challenges include keeping the process running in the background (daemonization), tracking its Flask is a Python micro-framework for web development. Mar 18, 2012 · 7 I'm implementing a long-running thread within a Flask application. Workflow Our goal is to develop a Flask application that works in I run an API (Python + Flask + Gunicorn) which has an endpoint that's calls a nested processes, which can sometimes take 6 seconds, to sometimes 60+ seconds to complete. This guide will show you how to configure Celery using Flask. Use multiprocessing. With Python's Quart is a reimplementation of Flask based on the ASGI standard instead of WSGI. Learn practical implementations and alternative solutions. Flask is a lightweight Python web framework that makes it easy to build scalable and testable Jan 28, 2025 · Learn how to integrate Celery with Flask for executing long-running tasks asynchronously, improving scalability and performance. ly/dash/). Data science models often require longer running computations for training or predicion, but HTTP requests that take longer than a few seconds to respond are at increased risk of failure. When deploying Flask applications in production, it is common to use a web server like Gunicorn to handle incoming requests. This is particularly true when your application communicates with third-party APIs, which can often introduce latency. Web services should never run long running tasks. Let’s get started. In this article, we will explore how to start a Flask application in a separate thread to ensure Nov 13, 2025 · Flask is a popular microframework for building web applications in Python, known for its simplicity and flexibility. Run long-running tasks in the background with a separate worker process. There are some existing questions about this, but none of the answers seem to address running a task after the response is sent to the client, they still execute synchronously and then the response is returned. But sometimes this doesn’t work and the work around is to get the process id of flask and use the kill command. Mar 22, 2013 · This is a bit old thread, but if someone experimenting, learning, or testing basic flask app, started from a script that runs in the background, the quickest way to stop it is to kill the process running on the port you are running your app on. It enables applications to asynchronously run tasks in the background by sending them to a distributed system of workers. celery --loglevel=info Now run the Flask app in another terminal by running the command: python app. Jul 20, 2012 · I found this question about "Flask auto-reload and long-running thread" which is somewhat related, but somewhat different, and the answer didn't help me. Arguments = ; start. For a particular endpoint, I use the request data to launch a potentially long running command. Dec 6, 2016 · The best way to implement background tasks in flask is with Celery as explained in this SO post. Just simply add this script to your flask application and invoke the /shutdown endpoint. Nov 13, 2025 · The solution? Run these tasks **asynchronously** in the background, allowing Flask to send an immediate response while the heavy work continues. The long task will run in the background, freeing up the Flask application to handle other requests. In this article, we will explore how to run Flask with Gunicorn in multithreaded mode to Dec 1, 2015 · From looking at examples, I thought that I could render a "please wait" template which returns immediately, while also calling my long running, run_analysis() function. Oct 8, 2019 · I am building a Flask MethodView driven API. Radis-queue (rq) is a library for queuing jobs and … Jul 23, 2025 · Flask is inherently synchronous, meaning each request is processed one at a time. Follow Twilio's expert tips to deploy your Flask application efficiently. This ensures that the web server remains responsive while handling the long-running tasks asynchronously. Key challenges include keeping the process running in the background (daemonization), tracking its Jul 31, 2022 · As I mentioned before, this will not work if you have more than one instance of the app running at once. Celery works well with web frameworks like Flask, Django, FastAPI, and can integrate with a variety of message brokers like RabbitMQ or Redis. Python Flask sending response immediately Need to execute a function after returning the response in Flask I am building REST API with Flask-restplus. , data processing, file conversions, or API calls to external services), as users will experience unresponsive 2 days ago · If you’re a Bluehost user running an Apache web server and want to deploy Python web applications, you’ve likely encountered terms like **CGI**, **WSGI**, and **Python web frameworks** (e. py: Mar 19, 2016 · I'm writing a small web server using Flask that needs to do the following things: On the first request, serve the basic page and kick off a long (15-60 second) data processing task. But how do they work together? And how do you set them up on Aug 29, 2024 · Learn how to implement effective logging in Python multiprocessing applications. Mar 31, 2022 · This tutorial will configure our Flask application to perform long-running tasks in the background using RQ (Redis Queue) Redis Queue is a Python library used for queueing and processing jobs in Mar 14, 2016 · I have an API. 5 days ago · Debugging a misbehaving Python application in production is often a high-stakes challenge. Feb 22, 2019 · I've got a long running, daemonized Python process that uses subprocess to spawn new child processes when certain events occur. The above document lists several options for . If I start again with 0 processes running, I get the same behavior consistently. Dec 15, 2024 · Python’s Flask framework is widely used for building web applications due to its simplicity and flexibility. Use join Proc. This issue perplexes many developers: Why does the 30-second May 21, 2021 · I have a Flask App which starts a long function after validation a form. Conceptually you would keep the long running tasks outside of your web request handling process. May 22, 2021 · This article looks at Flask 2. Read Celery’s First Steps with Celery guide to learn how to use Celery itself. Consider the following example: In this example, the long_running_process function simulates a process that takes some time to complete. API launchs a script, that may performs long time. RedirectStandardOutput = true; using (Process process = Process. Oct 20, 2018 · How to use Flask-APScheduler in your Python 3 Flask application to run multiple tasks in parallel, from a single HTTP request When you build an API endpoint that serves HTTP requests to work on long-running tasks, consider using a scheduler. This becomes problematic when your application needs to run **long-running scripts**—such as data processing, file conversions, or Jan 7, 2018 · Data Science APIs: Long Running Tasks 07 Jan 2018 This post is part of the series Data Science APIs. It is widely used in production environments due to its simplicity, compatibility with various frameworks, and efficient process management model. Jun 22, 2012 · It should not be taking this long for your responses but I have actually messed around with flask before to no success I would advise Bottlepy. Start(start)) { using (StreamReader reader = process. Sep 18, 2023 · The trick is to process these heavy requests in the background, allowing the application to continue serving other requests. This works by storing the state of in-flight requests in a global state inside your python process, so if you have more than one process, they won't all be working and modifying the same state. 7K subscribers Subscribed Nov 13, 2025 · Flask, a lightweight and flexible Python web framework, is beloved for its simplicity and "micro" design. May 20, 2024 · Flask is a popular web framework for building web applications in Python. May 16, 2024 · This is a long-running Flask API and to avoid complex in the design, we have some APIs that we will process requests in the background using multithreading. It is known for its simplicity and flexibility, making it a great choice for both small and large projects. What should I do if I need to use long running requests and I don't want to use celery. Celery is a powerful task queue that can be used for May 27, 2025 · Threading Example Implementation Utilize the threading module in Python. Containerize Flask and Redis with Docker. Discover best practices, advanced techniques, and solutions to common challenges. Set up RQ Dashboard to monitor queues, jobs, and workers. Whether you’re building a Flask/Django web app, a data pipeline, or a persistent service, you’ll learn how to balance performance and data accuracy. It has also already been possible to run Flask with Gevent or Eventlet to get many of the benefits of async request Feb 14, 2024 · Simplify background task automation by using ActiveBatch for job scheduling with Flask. Gunicorn is a pre-fork worker model server that can handle multiple concurrent requests efficiently. A good starting point is the official Flask documentation and the Celery documentation. Once this process is started, I want the function to return, while the new process keeps running independently. start () Proc. Fortunately, Python provides a Jun 25, 2021 · Using multiprocessing / thread-pools in Flask to run background or long running tasks is an anti-pattern. Knowledge of Python and basic knowledge of Flask is required. views. By using asyncio, you can write non-blocking code that allows other tasks to run concurrently while waiting for I/O operations to complete. Aug 6, 2013 · What, exactly, do you want your function to do after the request finishes? If it's write to a log, that's one thing, but if you want to return data to the user, there is no way to do that if the connection has indeed timed out. Two common approaches for this in Python are **threading** and **multiprocessing**. The request Jan 12, 2013 · The problem is that when I attempt to stop the web service (Ctrl+C on the built in development server) the child process stops instead, and the web server keep running in the background. Then once it's finished, grab the result. This article will explore its core features, configuration options, worker models, and best practices for deploying Gunicorn in Mar 21, 2023 · Learn about background tasks that run independently of the user interface, such as batch jobs, intensive processing tasks, and long-running processes. Nov 26, 2024 · Optimizing Flask Performance with async and await Introduction Optimizing Flask performance is crucial for any web application, especially when dealing with high-traffic or resource-intensive tasks. In debug mode, with the reloader activated, the long-running thread is not killed upon reload. To gain full voting privileges, I have a web-service that runs long-running jobs (in the order of several hours). Sep 19, 2018 · I'm trying to build a very simple Flask endpoint that just needs to call a long running, blocking php script (think while true {}). Jan 18, 2013 · Starting the thread from the non reloader process will prevent the thread from accessing your Flask app context (it runs in the reloader process), so depending on what you want to achieve, you have to decide between starting it from the main process (is_running_from_reloader() returning False) or the reloader process (is_running_from_reloader() returning True). Therefore, the question arises: How can you effectively implement asynchronous tasks in your Flask application? This Sep 7, 2012 · The flask process would add jobs to the message queue and a long running worker process (or pool or worker processes) would take jobs off the queue to complete them. Imagine we have a Flask app Dec 4, 2024 · Introduction Using Flask and Celery to Create a Background Task System In modern web development, handling requests and tasks in real-time can be challenging, especially when dealing with long-running or asynchronous processes. Sep 20, 2021 · Check out this same question: How to set connection read timeout and support flask run in multi-thread mode? · Issue #2351 · pallets/flask · GitHub Also, instead of making long-running query in the view/request handler, you may want to have it processed in the background, for example by using a task queue like celery. The job uses up to 30 seconds. One way to do this is by using the nohup command. Preventing multiple request for a long running process Hello r/flask! I'm looking for a good solution for a specific issue: The client is requesting through a SocketIO message a "calculation" that could take a minute to process. Users don't like this. BTW, on reload, the previous Flask is a Python micro-framework for web development. It provides a simple and flexible way to create web pages and handle user requests. But i dont know what 1 day ago · In this blog, we’ll demystify SQLAlchemy’s caching mechanisms, explain why stale data plagues long-running applications, and provide actionable strategies to avoid or mitigate it. The worker process could update a database to allow the flask server to know the current status of the job and pass this information to the clients. To solve your problem, consider using API <> Worker pattern. , Django, Flask). The code from flask import request def Nov 11, 2024 · Celery is a distributed task queue system in Python, designed to handle tasks asynchronously in the background, keeping applications responsive and reducing bottlenecks. from flask import Flask from threading import Thread app = Flask(__name__) def process_task(): # Perform long Nov 3, 2020 · I have a python flask app that waits for requests from user app and than spawns a process with job based on the request it receives. Learn how to use APScheduler and cron jobs to create tasks in Flask. What I am thinking of doing is to have the route which takes a long time to complete, call a function that creates a thread. UseShellExecute = false; start. My question is how to I update the progress bar as the function is running? Here is a simplified version of what I'm talking about. However, there may be scenarios where you need to stop the application programmatically, without relying on user input. Background tasks enable asynchronous execution, allowing Flask to process requests while tasks run concurrently. However, by default, Flask operates synchronously: each incoming request is processed in sequence, and the server blocks until the request is fully handled. Python subprocess (using Popen) hangs indefinitely and doesn't terminate when the script ends. Apr 27, 2025 · What is Celery? Celery is one of the most widely used task queue libraries for Python. Celery is a powerful task queue that can be used for simple background tasks as well as complex multi-stage programs and schedules. The interesting part is when I launch any other (or even the same configuration as another instance/process), both processes immediately appear and don't disappear back until I stop all of them. Thend pick it up in a different application that does the actual processing of the task. , data processing, file conversions, or machine learning inference) that block request handling. This can be useful for tasks such as processing data, making API calls, or running scheduled tasks. I already tried examples where you push the button an the progress bar just runs, but I notice that I don't have the experience to get how my Python function and the script in my HTML page communicate, so I can't get them connected. My code: from flask import Flask import subprocess app = Flask(__name__) @app. Nov 24, 2017 · celery worker -A app. Somehow it appears as if the web server job is suddenly pushed to becoming a background daemon while the child process now is the primary process. Instead, use a task queue to send the necessary data to another process that will run the task in the background while the request returns immediately. Aug 19, 2023 · Line 1 imports the flask_app object and long_running_task function from the tasks module. about 90 seconds. If you have BL that requires some long process, accept the request, generate a task id, schedule it via a message queue and then return the task id. These technologies are the backbone of how your Python code communicates with the web server and, ultimately, your users. . [Flask] - how to wait for a long running task to complete without blocking other requests. Nov 30, 2015 · The computation process is started via a post request in my flask application. Flask is a Python micro-framework for web development. This allows it to handle many concurrent requests, long running requests, and websockets without requiring multiple worker processes or threads. In such scenarios, **remotely accessing thread stacktraces** of a running process is invaluable: it lets you inspect the call stack of every active thread in real time Jun 21, 2020 · VSCode does that for all configuration types: debugpy, node. run(threaded=True) (as of Flask 1. , sending emails, processing large files, generating reports), executing them synchronously within a Flask request can lead to poor user experience—users wait indefinitely for a response while the task completes. I am building a python flask web app using the dash framework (https://plot. RemoteManager Start new process completely detached from Flask app. You can run a long-running monitoring task using a daemon thread and a while loop. join () Consider using queue with timeout, catch timeout exception on client side and listen It's important to execute long running process outside of Flask. I guess I could check if a process is running at the PID in the file, but what if another process has started and was assigned the PID of the dead process? Jun 1, 2024 · Flask and Asyncio: A Match Made in Heaven To tackle this problem, we’ll leverage Flask’s support for asyncio, a Python library that enables asynchronous I/O operations. But there is another way of addresssing this using a python function. First a bit of context: I have a bunch of jobs that are running in parallel on Google Cloud (GC). But I want to take this architecture to the Google Cloud platform. route('/data') def data(): mydata = super_long_process_function() # takes more than 5 minutes to process return mydata Since the super_long_process_function takes more than 5 minutes, it always times out with 504 Gateway Time-out. This can become a bottleneck when dealing with time-consuming tasks such as making API calls or performing database operations. Feb 17, 2022 · This tutorial looks at how to configure Celery to handle long-running tasks in a Flask app. 3 days ago · Flask, a lightweight and flexible Python web framework, excels at building web APIs and frontends, but it struggles with long-running tasks (e. However, when performing time-consuming tasks or executing functions that take a significant amount of time to complete, it is important to provide feedback to the user to avoid frustration or confusion. Introduction Let’s use an example to demonstrate how to add a background thread to Flask app. Why, and how to fix? Dec 1, 2015 · From looking at examples, I thought that I could render a "please wait" template which returns immediately, while also calling my long running, run_analysis() function. Scale the worker count with Docker. However, by default, Flask processes requests synchronously: each request blocks the server until it completes. May 28, 2025 · 01. So your data processing script needs to run outside of the webapp and somehow commuicate its status to the web app either via a database or a specific task-queue application If you work with flask have a look at flask-celery. I am developing this using Flask, Gunicorn, and nginx. The time it takes isn't a measure of my API's performance really, but rather its bottlenecked by an external service that the process has to rely on. In this app I have a few long running processes (asynchronous), locally I can process these jobs via celery. The data proces Jan 20, 2016 · 3 I'm building flask web app where user can start and manage processes. In this article, we will explore different approaches to gracefully stop a Flask application without using Ctrl-C. User selects options and clicks create video on front end React app calls /create_video API endpoint on Flask backend flask method calls render_video (data), which does several intensive things, including running a headless Chromium instance for web scraping, calling a text to speech API, and finally rendering a video using MoviePy. 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. This tutorial covers various methods to implement progress tracking, from simple console indicators to advanced GUI progress bars. I need to provide a REST API to send commands to this to this process and decided to do that with Flask. May 12, 2025 · I want to be able to terminate the process running a Celery task while it is running a long Python function within the task: @shared_task() def celery_task(): # I want to abort this task, Nov 6, 2024 · Discover various effective methods for stopping a Flask application gracefully without relying on Ctrl+C. This allows your main Flask application thread to continue processing other requests while the background threads work independently. Tools like Celery or Python’s threading, combined with NumPy Array Operations for data-intensive tasks, make Flask suitable for applications Mar 6, 2019 · Life’s too short to wait for long running tasks in your requests, Flask is simple and Celery seems just right to fit the need of having background jobs processing some uploaded data, sending Pass your long running task to an async library like Celery. Step 8: Testing Middleware and Flask REST API with Threadding | Run task in background Soumil Shah 44. It keeps the status and queue of the jobs in memory. In this tutorial you will discover how to execute long-running tasks in the background in Python. I don't want the job to block the main proces Jun 8, 2012 · 282 When running the development server - which is what you get by running app. Restarting the process to gather logs or reproduce the issue can disrupt services, lose critical state, or even mask the problem. Background Tasks with Celery If your application has a long running task, such as processing some uploaded data or sending email, you don’t want to wait for it to finish during a request. In this step-by-step tutorial, you’ll learn how to prevent freezing GUIs by offloading long-running tasks to worker QThreads in PyQt. Dec 9, 2024 · However, consuming messages from Kafka can often involve long-running processes, which can be challenging when trying to test, scale or manage them. It's designed to make getting started quick and easy, with the ability to scale up to complex applications. The flask function will execute the cumputation code and after the code and then the returned results will be stored in db. ReadToEnd(); Console. This becomes problematic when handling **long-running tasks** (e. You are reading the 2024… Nov 6, 2024 · In the realm of web development with Flask, you may encounter situations where you need to execute long-running tasks without blocking the main application. Jan 18, 2025 · In this tutorial, you'll learn how to leverage other apps and programs that aren't Python, wrapping them or launching them from your Python scripts using the subprocess module. One of the most effective ways to achieve this is by leveraging asynchronous programming with async and await. (I too have a separate long-running thread marked as a daemon thread, but it is killed when the reloader kicks in, but the problem I'm trying to solve is before any reload needs to happen. Jul 5, 2024 · Flask is a popular Python web framework known for its simplicity and flexibility. This isn't a Flask thing, this is just an HTTP thing; the browser, web server, or anything in between can close the connection. You'll learn about processes all the way up to interacting with a process as it executes. I have a long running process that loops indefinitely handling multiple requests with apparent asynchronicity using asyncio. As you can suppose an API must to response immediately but the Flask isn't asynchronous. Unlike short scripts, these processes run indefinitely, requiring careful management to ensure reliability, stability, and ease of maintenance. Im looking for any suggested libraries that can safely handle this secondary Aug 31, 2024 · In conclusion, adding a background thread to Flask in Python 3 allows you to perform long-running tasks without blocking the main Flask application. I've tried a few different methods to async launch the script, but the problem is my browser never actually receives the response back, even though the code for generating the response after running the script May 8, 2023 · Managing a long-running API listener using Python / Flask Asked 2 years, 6 months ago Modified 2 years, 6 months ago Viewed 1k times Flask is a Python micro-framework for web development. Why Run Background Tasks in Flask? Flask’s synchronous nature means long-running tasks can delay responses, degrading performance. This is useful for operations that need to happen after a request, but that the client doesn't really have to be waiting for the operation to complete before receiving the response. Using Background Workers For more intensive processing tasks, Flask can offload operations to background workers using task queues such as Celery. But there's a general better solution. After receiving a request, we start a new thread and return response to the end user. Say I had a single Flask application running on an EC2 instance, and 300+ requests were made from other machines at about the same time. Jul 23, 2025 · Example 2: Handling KeyboardInterrupt in a Long-Running Process In some cases, you may have a long-running process where you want to catch KeyboardInterrupt and perform cleanup operations before exiting. How can I prevent this, other than disabling the reloader? 3 days ago · Flask is a lightweight and flexible Python web framework, ideal for building web applications and APIs. The flask_app object, created in the tasks module, holds the Flask application's configuration, allowing Feb 5, 2023 · Offload long-running tasks using flask, radis and radis-queue (rq) Hi Devs👋, We often need to offload long-running tasks into the background. foz moskrqv ckx hlqv lbvk unlp nykkou rprcigx weemtm lxhanw pwctun klhiga nytdz zjuww qkiq