Environment variables

Here are the environment variables that zea uses at runtime. Arguably the most important environment variable is the Keras backend selection via KERAS_BACKEND. See the Backend section for details on configuring the backend.

Variable	Description	Default	Options
KERAS_BACKEND	Select the Keras backend to use. This defines the ML framework that will be used for all tensor operations. Takes precedence over the backend in keras.json. If neither is set, zea picks an installed backend on import (preferring tensorflow, then jax, then torch).	installed backend	tensorflow, jax, torch, numpy
ZEA_CACHE_DIR	Directory to use for caching downloaded files, e.g. model weights or datasets from Hugging Face Hub.	~/.cache/zea	str
ZEA_LOG_LEVEL	Logging level for zea.	DEBUG	DEBUG, INFO, WARNING, ERROR, CRITICAL
ZEA_DISABLE_CACHE	If set to 1 will write to a temporary cache directory that is deleted after the program exits.	0	0, 1
ZEA_NVIDIA_SMI_TIMEOUT	Timeout in seconds for calling nvidia-smi to get GPU information during zea.init_device().	30	Any positive integer, or <= 0 to disable timeout.
ZEA_DOWNLOAD_TIMEOUT	Timeout in seconds for downloading files, e.g. during dataset conversion.	60	Any positive integer, or <= 0 to disable timeout.
ZEA_FIND_H5_SHAPES_PARALLEL	If set to 1, will use parallel processing for the per-file sweeps over a dataset (reading HDF5 file shapes, and validating files against the zea format).	1	0, 1
ZEA_TEST_DEVICE	Can be used to only run the tests with a particular device.	auto:1	Any valid device name as accepted by zea.init_device(). For example, cpu, cuda:0, auto:1, etc.
ZEA_HF_CACHE_TTL	Seconds a Hugging Face repository listing or resolved download path may be reused before zea asks the hub again. Keeps a dataset scan or preset load from repeating the same request; set to 0 if you need every call to hit the hub (e.g. a repo being written to from elsewhere while you read it).	300	Any number of seconds, 0 to disable.
ZEA_CHUNK_CACHE	Cache chunks fetched while streaming (hf://) under ZEA_CACHE_DIR/chunks, so a repeated read is served from disk instead of re-downloaded. Keyed by content hash, so a re-uploaded file misses rather than serving stale bytes. Per-file: File(cache=False).	1	0, 1
ZEA_CHUNK_CACHE_SIZE	Byte budget for that cache; least-recently-used chunks are evicted once it is exceeded.	10737418240 (10 GiB)	Any positive integer (bytes).
BLOSC_NTHREADS	Threads Blosc uses within a single HDF5 chunk, which is most of the write throughput (~4x). Turn it down when writes are already parallel (several dataloader workers each saving a file will multiply with it); turning it far up backfires, as the blocks go memory-bound. Only affects writes: the read path (zea.data.chunk_reader) uses numcodecs, which has its own thread setting.	min(8, cpu_count)	Any positive integer.