SLslach·Aug 25, 2025
In Show HN: AsyncFlow – stop guessing p95 latency, simulate your system before prodAsyncFlow-Sim
AsyncFlow
Python2025–2025
AsyncFlow-Sim / AsyncFlow
AsyncFlow
Scenario-driven simulator for async distributed systems: declare topologies, run simulations, measure latency/throughput, resource usage and see where bottlenecks emerge.
2Distinct people
2Mentions
0Explicit recommenders
82GitHub stars
What to know before exploring
What it is
Scenario-driven simulator for async distributed systems: declare topologies, run simulations, measure latency/throughput, resource usage and see where bottlenecks emerge.
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
No recommendation phrase was found in the indexed comments.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
No other repository is repeatedly linked in the same discussions.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 12:54:37 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by 6-hour interval2 dated mentions
Observed mentions: 2025-08-19 16:14:00 UTC to 2025-08-25 04:00:41 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| Aug 19, 12:00 | 2025-08-19 12:00:00 UTC | 2025-08-19 18:00:00 UTC | 1 | 1 | 0 |
| Aug 19, 18:00 | 2025-08-19 18:00:00 UTC | 2025-08-20 00:00:00 UTC | 0 | 0 | 0 |
| Aug 20, 00:00 | 2025-08-20 00:00:00 UTC | 2025-08-20 06:00:00 UTC | 0 | 0 | 0 |
| Aug 20, 06:00 | 2025-08-20 06:00:00 UTC | 2025-08-20 12:00:00 UTC | 0 | 0 | 0 |
| Aug 20, 12:00 | 2025-08-20 12:00:00 UTC | 2025-08-20 18:00:00 UTC | 0 | 0 | 0 |
| Aug 20, 18:00 | 2025-08-20 18:00:00 UTC | 2025-08-21 00:00:00 UTC | 0 | 0 | 0 |
| Aug 21, 00:00 | 2025-08-21 00:00:00 UTC | 2025-08-21 06:00:00 UTC | 0 | 0 | 0 |
| Aug 21, 06:00 | 2025-08-21 06:00:00 UTC | 2025-08-21 12:00:00 UTC | 0 | 0 | 0 |
| Aug 21, 12:00 | 2025-08-21 12:00:00 UTC | 2025-08-21 18:00:00 UTC | 0 | 0 | 0 |
| Aug 21, 18:00 | 2025-08-21 18:00:00 UTC | 2025-08-22 00:00:00 UTC | 0 | 0 | 0 |
| Aug 22, 00:00 | 2025-08-22 00:00:00 UTC | 2025-08-22 06:00:00 UTC | 0 | 0 | 0 |
| Aug 22, 06:00 | 2025-08-22 06:00:00 UTC | 2025-08-22 12:00:00 UTC | 0 | 0 | 0 |
| Aug 22, 12:00 | 2025-08-22 12:00:00 UTC | 2025-08-22 18:00:00 UTC | 0 | 0 | 0 |
| Aug 22, 18:00 | 2025-08-22 18:00:00 UTC | 2025-08-23 00:00:00 UTC | 0 | 0 | 0 |
| Aug 23, 00:00 | 2025-08-23 00:00:00 UTC | 2025-08-23 06:00:00 UTC | 0 | 0 | 0 |
| Aug 23, 06:00 | 2025-08-23 06:00:00 UTC | 2025-08-23 12:00:00 UTC | 0 | 0 | 0 |
| Aug 23, 12:00 | 2025-08-23 12:00:00 UTC | 2025-08-23 18:00:00 UTC | 0 | 0 | 0 |
| Aug 23, 18:00 | 2025-08-23 18:00:00 UTC | 2025-08-24 00:00:00 UTC | 0 | 0 | 0 |
| Aug 24, 00:00 | 2025-08-24 00:00:00 UTC | 2025-08-24 06:00:00 UTC | 0 | 0 | 0 |
| Aug 24, 06:00 | 2025-08-24 06:00:00 UTC | 2025-08-24 12:00:00 UTC | 0 | 0 | 0 |
| Aug 24, 12:00 | 2025-08-24 12:00:00 UTC | 2025-08-24 18:00:00 UTC | 0 | 0 | 0 |
| Aug 24, 18:00 | 2025-08-24 18:00:00 UTC | 2025-08-25 00:00:00 UTC | 0 | 0 | 0 |
| Aug 25, 00:00 | 2025-08-25 00:00:00 UTC | 2025-08-25 06:00:00 UTC | 1 | 0 | 1 |
What Hacker News says
2 sourcesShow HN: AsyncFlow – Event-loop aware simulator for async distributed systems
Hi HN,
I’m a theoretical-physics–turned–software engineer, and over the last several months I built AsyncFlow, an open-source discrete-event simulator for asynchronous distributed backends.
Idea: create a digital twin of your service before you deploy. You define a topology in YAML (client → optional load balancer → N servers → network edges with stochastic latency) and a workload driven by a stochastic request generator. The simulator runs full request lifecycles through each server’s event loop with explicit models for CPU work (blocking), I/O waits (non-blocking), and RAM residency.
What you get: production-like metrics (p50/p95/p99 latency, RPS, queue lengths) and plots to answer questions like “How many cores do I need to keep p99 < 100 ms?” without spinning up infra or running an expensive load test.
Example with output (2-server LB
Read the rest
):
https://github.com/AsyncFlow-Sim/AsyncFlow/tree/main/example...
Quick start
pip install asyncflow-sim
Repo & README: https://github.com/AsyncFlow-Sim/AsyncFlow
Why this vs load testing? Load tests (Locust, k6) measure a real system. AsyncFlow simulates one that doesn’t exist yet, so you can compare designs and size capacity offline, then validate with a load test later.
Status (alpha):
Works end-to-end; strict Pydantic schemas; ready-made plots; Pythonic builder.
Limits: simple network (latency + optional drops), single event loop per server, linear endpoint flows, no thread concurrency, single core per server.
Roadmap: Monte Carlo runs w/ confidence intervals, event injection (server down/up, network spikes), cache step, richer network model, richer nodes structure.
I’d love feedback on:
- YAML vs Python builder ergonomics
- Which metrics/plots you want by default
- Realistic knobs you’re missing for what-if capacity planning
MIT-licensed. Thanks!