loopsentry 0.1.1

asyncio Eventloop Blockers Detector/Analyzer.

LoopSentry

Asyncio Event Loop Blockers Detector & Analyzer

• utility for detecting blocking calls in asyncio event loops

Installation

uv add loopsentry

pip way

pip install loopsentry

Usage

1. Basic Usage

import asyncio
from loopsentry import LoopSentry

async def main():
    # start monitoring (default threshold: 0.1s) ie: if blocks is >= 0.1 , it is logged
    sentry = LoopSentry(threshold=0.1,
                        capture_args=False, # this is basically do you want to capture arguments of functions at the time
                        detect_async_bottlenecks=False) # other than blocking it also detects slow asyncio tasks which are going on. helps to find bottlenecks
    sentry.start()

    print("Running...")
    ... # rest of your application

if __name__ == "__main__":
    asyncio.run(main())

2. Use inside Uvicorn/gunicorn workers in fastapi

• you need to put it inside a lifespan context manager , so if you use multiple workers eachh gets their own LoopSentry instance

from contextlib import asynccontextmanager
from fastapi import FastAPI
from loopsentry import LoopSentry

@asynccontextmanager
async def lifespan(app: FastAPI):
    sentry = LoopSentry()
    sentry.start()
    yield

app = FastAPI(lifespan=lifespan)

@app.get("/")
async def root():
    return {"message": "I am being monitored!"}

Log Analysis

uv run loopsentry analyze -d log_directory

NOTE: if you used pip to install then

loopsentry analyze -d log_directory

CLI Controls

• /text: Search/Filter logs.
• g: Group view (see top offenders).
• s: Sort by Duration vs Time.
• ID: Enter an ID number to view stack trace & arguments.

Gallery

1. Traceback with Argument Capture

Pinpoint exactly where the code blocked and what arguments caused it.

2. Grouped View (Top Offenders)

Quickly identify which files or functions are causing the most performance hits.

3. Slow Async Task Detection

Detect tasks that are async but still taking too long (Bottlenecks).