JAX has limited support for Python concurrency.

Clients may call JAX APIs (e.g., jit() or grad()) concurrently from separate Python threads.

It is not permitted to manipulate JAX trace values concurrently from multiple threads. In other words, while it is permissible to call functions that use JAX tracing (e.g., jit()) from multiple threads, you must not use threading to manipulate JAX values inside the implementation of the function f that is passed to jit(). The most likely outcome if you do this is a mysterious error from JAX.