quantumlib / Cirq

A Python framework for creating, editing, and invoking Noisy Intermediate Scale Quantum (NISQ) circuits.
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Update `cirq.RANDOM_STATE_OR_SEED_LIKE` to support `np.random.Generator` #6531

Open NoureldinYosri opened 6 months ago

NoureldinYosri commented 6 months ago

Is your feature request related to a use case or problem? Please describe. We have several modules that spwan multiple threads for performance. each of those threads would be running a random operation using a random state or state. when those threads share the same RandomState the multithreading degenerate into sequential processing since those threads will be waiting on write operation of the random state.

Describe the solution you'd like Start supproting np.random.Generator. This class provides the same API of np.random.RandomState in addition to a spawn function which can be used to create independent streams of random values. This will help when starting threads e.g.

   new_random_generators = prng.spwan(number_threads)
  with ThreadPoolExecutor(max_workers=2) as pool:
          # submit job i with prng new_random_generators[i]

Describe alternatives/workarounds you've considered Before calling multithreads generate multipleseeds using a np.random or RandomState. While this seems like what we are doing with np.random.Generator.spawn; it's actually different in that the radom seeds and hence the random sequences created will correlate. This means that when running the same operation (e.g. simulation) multiple times in parallel, the results will correlate.

state_0 -> state_1 -> state_2 -> ...
  \         \          \         \
   v         v          v         v
   output_0 output_1   output_2  ....

Additional context (e.g. screenshots) The cirq random number support is implemented in cirq-core/cirq/value/random_state.py

What is the urgency from your perspective for this issue? Is it blocking important work? P2 - we should do it in the next couple of quarters

mhucka commented 6 months ago

There was a past issue involving np.random and multiprocessing. It may not be a concern with the present issue, but on the off chance that there are implications for this issue, it seemed worth pointing to it: #3717 ("Can't use cirq.Simulator() in a multiprocessing closure (unable to pickle)")

kitsiosvas commented 3 weeks ago

Is this issue still open @NoureldinYosri ? I would be interested if so

NoureldinYosri commented 3 weeks ago

@kitsiosvas yes, it's still open. I have an old PR for this https://github.com/quantumlib/Cirq/pull/6566 you can take over it and continue this work if you want to.