[FEATURE] mutex/cond for multi-threading?

**Is your feature request related to a problem? Please describe.**
Should there be a mutex/cond stuff in std:thread ?

**Describe the solution you'd like**
mutex/cond in std:thread or `std:mutex`, `std:cond`

**Describe alternatives you've considered**
Maybe more abstract of lock/unlock if co-routine is supported later.

This will be very helpful for multi-threading applications. Thanks.