API compatibility

API compatibility#

JAX is constantly evolving, and we want to be able to make improvements to its APIs. That said, we want to minimize churn for the JAX user community, and we try to make breaking changes rarely.

JAX follows a 3 month deprecation policy. When an incompatible change is made to an API, we will make our best effort to obey the following procedure:

  • the change will be announced in CHANGELOG.md and in the doc string for the deprecated API, and the old API will issue a DeprecationWarning.

  • three months after the jax release that deprecated an API, we may remove the deprecated API at any time. Note that three months is a lower bound, and is intentionally chosen to be faster than that of many more mature projects. In practice, deprecations may take considerably longer, particularly if there are many users of a feature. If a three month deprecation period becomes problematic, please raise this with us.

We reserve the right to change this policy at any time.

What is covered?#

Only public JAX APIs are covered, which includes the following modules:

  • jax

  • jax.dlpack

  • jax.image

  • jax.lax

  • jax.nn

  • jax.numpy

  • jax.ops

  • jax.profiler

  • jax.random (see details below)

  • jax.scipy

  • jax.tree

  • jax.tree_util

  • jax.test_util

Not everything in these modules is intended to be public, and over time, we are working to separate public and private APIs. Public APIs are documented in the JAX documentation. Additionally, our goal is that all non-public APIs should have names prefixed with underscores, although we do not entirely comply with this yet.

What is not covered?#

  • anything prefixed with an underscore.

  • jax._src

  • jax.core

  • jax.lib

  • jax.interpreters

  • jax.experimental

  • jax.example_libraries

  • jax.extend (see details)

This list is not exhaustive.

Numerics and randomness#

The exact values of numerical operations are not guaranteed to be stable across JAX releases. In fact, exact numerics are not necessarily stable at a given JAX version, across accelerator platforms, within or without jax.jit, and more.

For a fixed PRNG key input, the outputs of pseudorandom functions in jax.random may vary across JAX versions. The compatibility policy applies only to the output distribution. For example, the expression jax.random.gumbel(jax.random.key(72)) may return a different value across JAX releases, but jax.random.gumbel will remain a pseudorandom generator for the Gumbel distribution.

We try to make such changes to pseudorandom values infrequently. When they happen, the changes are announced in the changelog, but do not follow a deprecation cycle. In some situations, JAX might expose a transient configuration flag that reverts the new behavior, to help users diagnose and update affected code. Such flags will last a deprecation window’s amount of time.

Contents