All Questions
27 questions
102
votes
2
answers
84k
views
FastAPI runs API calls in serial instead of parallel fashion
I have the following code:
from fastapi import FastAPI, Request
import time
app = FastAPI()
@app.get("/ping")
async def ping(request: Request):
print("Hello")
time....
- 2,882
72
votes
4
answers
87k
views
FastAPI asynchronous background tasks blocks other requests? [duplicate]
I want to run a simple background task in FastAPI, which involves some computation before dumping it into the database. However, the computation would block it from receiving any more requests.
from ...
- 1,048
54
votes
6
answers
41k
views
Sharing python objects across multiple workers
We have created a service using FastAPI. When our service starts it creates a few python objects that the endpoints then use to store or retrieve data from.
FastAPI in production starts with multiple ...
- 1,091
26
votes
1
answer
24k
views
asyncpg - cannot perform operation: another operation is in progress
I am attempting to resolve the following error:
asyncpg.exceptions._base.InterfaceError: cannot perform operation: another operation is in progress
Here is the full traceback:
Traceback (most recent ...
- 1,014
12
votes
2
answers
19k
views
What does async actually do in FastAPI? [duplicate]
I have two scripts:
from fastapi import FastAPI
import asyncio
app = FastAPI()
@app.get("/")
async def root():
a = await asyncio.sleep(10)
return {'Hello': 'World',}
And second ...
- 913
9
votes
1
answer
6k
views
Fastapi testing RuntimeError: Task attached to a different loop
I trying to test my endpoint with pytest
main.py:
from fastapi import FastAPI, status, HTTPException, Depends
from sqlalchemy.ext.asyncio import AsyncSession
from .schema import ClientIn, ClientOut, ...
- 131
6
votes
1
answer
3k
views
Will run_in_executor ever block?
suppose if I have a web server like this:
from fastapi import FastAPI
import uvicorn
import asyncio
app = FastAPI()
def blocking_function():
import time
time.sleep(5)
return 42
@app.get(...
- 7,441
5
votes
1
answer
5k
views
Difference between await Coroutine and await Task
On FastAPI, I have an endpoint that calls get_1 or get_2 coroutine function below.
get_1 uses await redis.get(key)
get_2 uses await asyncio.ensure_future(redis.get(key))
Is there any difference ...
- 2,801
5
votes
2
answers
4k
views
Call async function from sync inside async FastAPI application
Not sure, that this is possible, but still
I have default async FastAPI application, where I have sync function
@classmethod
def make_values(
cls,
records: list,
symbol: str = ...
- 2,342
4
votes
2
answers
3k
views
Python: Call asynchronous code from synchronous method when there is already an event loop running [duplicate]
I am working with FastAPI and uvloop to serve a REST API in an efficient way.
I have a lot of asynchronous code that make calls to remote resources such as a database, a storage, etc, those functions ...
- 787
3
votes
1
answer
1k
views
FastAPI async routes deadlock bug when using infinite loop [duplicate]
I am experiencing an issue with FastAPI where the application gets deadlocked when using an infinite loop in an async route. Here is a simplified version of my FastAPI application (fastapi_test.py):
...
- 41
3
votes
1
answer
2k
views
How to apply FastAPI Middleware on "non-async def" endpoints? [duplicate]
According to https://fastapi.tiangolo.com/tutorial/middleware/, we could apply a FastAPI Middleware on async def endpoints.
Currently I have several non-async def endpoints, how to apply FastAPI ...
- 2,471
2
votes
2
answers
534
views
FastAPI TestClient not starting lifetime in test
Example code:
import os
import asyncio
from contextlib import asynccontextmanager
from fastapi import FastAPI, Request
@asynccontextmanager
async def lifespan(app: FastAPI):
print(f'Lifetime ON {...
- 7,322
1
vote
1
answer
205
views
AttributeError: 'function' object has no attribute 'submit' [duplicate]
I am using fastapi and uvicorn as my python server and whenever a user visits a route, I want to start a subprocess in the background. I used asyncio.create_task and loop.run_in_excutor in order to ...
- 87
1
vote
1
answer
6k
views
How do I call an async function in a new process using multiprocessing? [duplicate]
I created a server that wait for webhook signal, and when there is signal, it will create a new process to run the loop() function, and when running the loop() function, I want it to call the function ...
- 231