Hacker News
Show HN: ZSE – Open-source LLM inference engine with 3.9s cold starts
I've been building ZSE (Z Server Engine) for the past few weeks — an open-source LLM inference engine focused on two things nobody has fully solved together: memory efficiency and fast cold starts.
The problem I was trying to solve:
Running a 32B model normally requires ~64 GB VRAM. Most developers don't have that. And even when quantization helps with memory, cold starts with bitsandbytes NF4 take 2+ minutes on first load and 45–120 seconds on warm restarts — which kills serverless and autoscaling use cases.
What ZSE does differently:
Fits 32B in 19.3 GB VRAM (70% reduction vs FP16) — runs on a single A100-40GB
Fits 7B in 5.2 GB VRAM (63% reduction) — runs on consumer GPUs
Native .zse pre-quantized format with memory-mapped weights: 3.9s cold start for 7B, 21.4s for 32B — vs 45s and 120s with bitsandbytes, ~30s for vLLM
All benchmarks verified on Modal A100-80GB (Feb 2026)
It ships with:
OpenAI-compatible API server (drop-in replacement)
Interactive CLI (zse serve, zse chat, zse convert, zse hardware)
Web dashboard with real-time GPU monitoring
Continuous batching (3.45× throughput)
GGUF support via llama.cpp
CPU fallback — works without a GPU
Rate limiting, audit logging, API key auth
Install:
-----
pip install zllm-zse
zse serve Qwen/Qwen2.5-7B-Instruct
For fast cold starts (one-time conversion):
-----
zse convert Qwen/Qwen2.5-Coder-7B-Instruct -o qwen-7b.zse
zse serve qwen-7b.zse # 3.9s every time
The cold start improvement comes from the .zse format storing pre-quantized weights as memory-mapped safetensors — no quantization step at load time, no weight conversion, just mmap + GPU transfer. On NVMe SSDs this gets under 4 seconds for 7B. On spinning HDDs it'll be slower.
All code is real — no mock implementations. Built at Zyora Labs. Apache 2.0.
Happy to answer questions about the quantization approach, the .zse format design, or the memory efficiency techniques.
Comments URL: https://news.ycombinator.com/item?id=47160526
Points: 18
# Comments: 1
