On Monday, May 25, 2020 redradist@gmail.com [mailto:redradist@gmail.com] wrote
Edwin Zimmerman wrote:
On 5/25/2020 5:56 AM, redradist@gmail.com wrote:
Edwin Zimmerman wrote: Sub-interpreters are a work in progress. The API is not anywhere near being finalized. True parallel execution will occur only if the GIL is changed to a per interpreter lock, and that requires some rather large changes to Python that haven't happened yet.
Why ? True parallel execution is possible with sub-interpreters !!
`Sub-interpretter` should be run in separate thread not controlled by GIL and `sub-interpretter` will notify `main interpreter` with `atomic variable` that it is finished (like worker) !! We just need to provide two APIs: 1) Synchronized: `run`, `run_string`, that will wait until thread notify with setting `atomic variable` in true that it finished 2) Asynchronized (based on async): `run_async`, `run_string_async`, event_loop will wait on `atomic variable` reading it periodically
All sub-interpreters and all threads are subject to the GIL, that is why it is called the GLOBAL Interpreter Lock. There is no such thing as a "separate thread not controlled by GIL." This is not a problem with the sub-interpreter API. It is a design decision embedded very deeply through the entire CPython code. It is not trivial to change this. However, there is work being done on this. Search the python-dev mailing list for the "PoC: Subinterpreters 4x faster than sequential execution or threads on CPU-bound workaround" thread if you want to see more. --Edwin