For the purposes of:

• Improving some API's semantics which based on one actor per process, such as kill(actor)..
• Clearing the gap and redundant codepath of PG and actors scheduling between Python and Java.
• Addressing other potential risks since the feature flag is off in opensource codebase currently.
• Speeding up the process to opensource gcs scheduling.
• Improving actor isolation.

We'd like to remove all code path of multi-actors-per-process and have not been support the feature. As an alternate, we'd like to support another parallel execution model based on concurrency group, which is as a separate util library of commonlibs. The new util is on the top of actor, hence it won‘t break the assumption of one actor per process.