BrokenProcessPool: Process Pool Not Running

Why This Happens

BrokenProcessPool occurs when a worker process dies from segfaults, memory errors, or unpicklable exceptions. The pool becomes unusable after this.

The Problem

from concurrent.futures import ProcessPoolExecutor

def process(data):
    return risky_operation(data)

with ProcessPoolExecutor() as pool:
    results = list(pool.map(process, items))

The Fix

from concurrent.futures import ProcessPoolExecutor

def process(data):
    try:
        return risky_operation(data)
    except Exception:
        return None

with ProcessPoolExecutor(max_workers=4) as pool:
    futures = [pool.submit(process, item) for item in items]
    results = [f.result() for f in futures]

Step-by-Step Fix

1. 1

   Handle exceptions in workers

   Catch all exceptions inside worker functions.

2. 2

   Use submit() for per-task errors

   Use pool.submit() instead of pool.map().

3. 3

   Consider ThreadPoolExecutor

   Threads avoid process-level crashes for I/O work.