# NUTS doesn't run even with the simplest of models?

**URL:** <https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341>\
**Category:** Questions\
**Created:** [December 2, 2020, 1:49am UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341 "2020-12-02T01:49:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Oztotl](https://avatars.discourse-cdn.com/v4/letter/o/b38774/32.png) [@Oztotl](https://discourse.pymc.io/u/Oztotl)\
**Post date:** [December 2, 2020, 1:49am UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341/1 "2020-12-02T01:49:01Z")

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I am just getting started with PyMC3 and have tried to run a extremely simple example from Osvaldo Martin’s book, but NUTS seems to get hung up during initialization:

> data = stats.bernoulli.rvs(p=0.35, size=4)  
> with pm.Model() as simple\_model:  
> theta = pm.Beta(‘theta’, alpha=1., beta=1.)  
> y = pm.Bernoulli(‘y’, p=theta, observed=data)  
> trace = pm.sample(1000, random\_seed=123)

gives:

> Auto-assigning NUTS sampler…  
> Initializing NUTS using jitter+adapt\_diag…  
> Multiprocess sampling (4 chains in 4 jobs)  
> NUTS: [theta]

If I set chains=1 it initializes with 1 job and runs. However, if I set chains=2 and cores=2, it hangs again. What might be going wrong? I am using Python 3.8.3 and Anaconda 2020.11 on Windows 10.

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**Author:** ![twiecki](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.pymc.io/twiecki/32/6930_2.png) [@twiecki](https://discourse.pymc.io/u/twiecki)\
**Post date:** [December 2, 2020, 8:16am UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341/2 "2020-12-02T08:16:25Z")

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Unfortunately parallelism on windows is still a bit unstable sometimes. The next version 3.10 which is coming out soon should have some fixes for that, however.

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**Author:** ![Oztotl](https://avatars.discourse-cdn.com/v4/letter/o/b38774/32.png) [@Oztotl](https://discourse.pymc.io/u/Oztotl)\
**Post date:** [December 2, 2020, 10:09am UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341/3 "2020-12-02T10:09:27Z")

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Thanks for the reply. I suppose that means there isn’t a short-term work around for running parallel jobs? In any case, looking forward to your next release then!

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**Author:** ![nkaimcaudle](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.pymc.io/nkaimcaudle/32/2142_2.png) [@nkaimcaudle](https://discourse.pymc.io/u/nkaimcaudle)\
**Post date:** [December 3, 2020, 12:15am UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341/4 "2020-12-03T00:15:07Z")

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Some people have reported good success using [WSL2](https://www.omgubuntu.co.uk/how-to-install-wsl2-on-windows-10)

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**Author:** ![twiecki](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.pymc.io/twiecki/32/6930_2.png) [@twiecki](https://discourse.pymc.io/u/twiecki)\
**Post date:** [December 15, 2020, 3:47pm UTC](https://discourse.pymc.io/t/nuts-doesnt-run-even-with-the-simplest-of-models/6341/5 "2020-12-15T15:47:31Z")

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3.10 is out now. Can you try if that fixes your parallelism problem?