FAQ
FAQ
Direct answers to the questions that come up most in issues, Discord, and code review.
- Fingerprinting
Two identical checkpoints produce different fingerprints. Why?
The most common cause is non-deterministic weight init inside a wrapper class the adapter does not recognize. Runns.fingerprint(model, kind="arch")andkind="weights"separately: ifarchmatches andweightsdoes not, one checkpoint has bytes the other does not. Ifarchalso differs, the module tree is not the same — check for lazily-created buffers. - Fingerprinting
Does the fingerprint depend on device or dtype?
No. Fingerprints are computed on a CPU snapshot cast to a canonical dtype. Moving a model between CUDA and CPU, or betweenfloat16andbfloat16, does not change the digest. - Recording
The recorder raised E2201 (collator stalled). What do I do?
The dataset iterator is producing rows faster than the writer can drain the ring buffer. Either raisebuffer_mb, lower recording throughput (fewer probes, wider stride), or pointNS_ARTIFACT_DIRat faster storage. See common errors for a full triage tree. - Recording
Can I record from a model I did not train?
Yes. Adapters exist for HuggingFacetransformers, raw PyTorch modules, JAX pytrees, and any object exposing astate_dict()-like surface. See the Model concept for the full adapter matrix. - Comparison
Can I compare a fine-tuned model against its base checkpoint?
That is the intended workflow. Both artifacts share the architecture fingerprint (comparison is allowed) and differ in the weights fingerprint (which is what the report describes). - Comparison
Can I compare across frameworks (PyTorch vs. JAX)?
Only if the layer names align. NeuronScope does not implement a cross-framework name mapping — pass an explicitalignment=map tons.compare()or usens diff --alignment. - Storage
How big are .nsz files in practice?
Roughlybatch × tokens × hidden × layers × 2 bytesfor afloat16activation recording, plus ~2% overhead for the fingerprint index. See Benchmarks for concrete numbers. - Storage
Can I stream .nsz files from S3 without downloading?
Yes — see the Cloud storage recipe. Range reads pull only the layer index and the requested tensors. - Project
How is NeuronScope licensed?
Apache 2.0 for both the library and the CLI. The Rust reader crate is dual MIT/Apache 2.0. - Project
Is there a hosted service?
Not from the maintainers. NeuronScope is a local tool that writes files. Third-party hosted dashboards read the same.nszformat — see Ecosystem.