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python.asyncio.missing_timeout

Stability Medium

Detects async operations that should have timeouts but don’t, which can lead to tasks hanging indefinitely.

Why It Matters

Async operations without timeouts can:

Hang indefinitely — A single stuck task can hold resources forever
Exhaust connection pools — Tasks waiting on unresponsive services never release connections
Cascade failures — One slow operation can block entire request pipelines
Prevent graceful shutdown — Untimed operations ignore cancellation signals

Example

# ❌ Before (can wait forever)
import asyncio

async def main():
    done, pending = await asyncio.wait(tasks)

async def get_from_queue(queue):
    item = await queue.get()  # Blocks forever if empty

# ✅ After (bounded waiting)
import asyncio

async def main():
    done, pending = await asyncio.wait(tasks, timeout=30.0)
    # Handle pending tasks
    for task in pending:
        task.cancel()

async def get_from_queue(queue):
    try:
        item = await asyncio.wait_for(queue.get(), timeout=30.0)
    except asyncio.TimeoutError:
        # Handle timeout
        pass

What Unfault Detects

asyncio.wait() without timeout parameter
asyncio.gather() without timeout wrapper
Queue.get() without timeout
Lock.acquire() without timeout
Very long asyncio.sleep() calls without cancellation support

Auto-Fix

Unfault generates patches that add appropriate timeout parameters to async operations:

# asyncio.wait with timeout
done, pending = await asyncio.wait(tasks, timeout=30.0)

# asyncio.gather with timeout wrapper (Python 3.11+)
async with asyncio.timeout(30.0):
    results = await asyncio.gather(task1, task2, task3)