Do you have a specific PBT implementation you are considering ?

Yes. Ray has a nice implementation of that and of many other things (It also supports Optuna & BOHB internally). This could relate to a https://github.com/allegroai/trains/issues/227#issuecomment-716513710 I opened in the GIT.

TPE and HBOB are competitive to PBT in terms of performance

Yes, and I believe ASHA is also, but I wanted to compare PBT.

Thanks anyway.

Hi OddAlligator72

it 

 that they do not support PBT.

The optimization algorithm themselves are usually external (although the trivial stuff are in within Trains)
Do you have a specific PBT implementation you are considering ?

FYI:
TPE and HBOB are competitive to PBT in terms of performance