TypeError: cannot pickle 'ThreadLocalSampler' object: Cannot serialize AutoSampler due to ThreadLocalSampler

[muhlbach]

Hi!

Please note that the AutoSampler cannot be serialized because at instantiation, it sets self._thread_local_sampler = ThreadLocalSampler(), and this instantiates threading.local. I think __get_state__ and __setstate__ should be updated to account for serialization of ThreadLocalSampler() attributes.

To reproduce the error, run

import dill
import optunahub

sampler = optunahub.load_module("samplers/auto_sampler").AutoSampler()
dill.dumps(sampler)

and it will fail with TypeError: cannot pickle 'ThreadLocalSampler' object.

[nabenabe0928]

Hi @muhlbach!

Thank you for the report:)
I am working on this issue now!

[nabenabe0928]

I will close this issue as it's been addressed by:

• Fix the pickle error in AutoSampler optunahub-registry#238

[muhlbach]

Amazing, thanks @nabenabe0928