Jython, GILs and object locking.

[Harri Pesonen]

Daniel Dittmar wrote:
> Harri Pesonen wrote:
> 
>> You are probably asking next "how threads can communicate". They can 
>> communicate with messages, and via special shared interpreter state, 
>> which needs a new "shared" keyword in python. Access to these shared 
>> variables is synchronized, all other variables are local to thread, 
>> and they need not be synchronized.
> 
> So you're not talking about Python threads in the meaning of the module 
> 'thread'. Instead you want to be able to create multiple interpreters in 
> the same process and run them in parallel via threads. Today, the Global 
> in GIL is really global instead of interpreter local.

Exactly. But Viper (my free-threading Python) will have something 
similar to 'thread' modules as well, maybe I call it 'freethreading'. 
Thread created by this module will also have independent interpreters. 
They can communicate with the above methods, but their other variables 
are local.

> I'm not saying that this isn't a worthy goal. Server applications with 
> embedded Python interpreters would profit from it and it is not that 
> difficult to implement. (Although keeping the patches current with 
> Python development will be awful as adding the interpreter state will 
> affect every call at the C level).

I have a Python script that does the conversion. It already handles the 
following static objects:

Py_None, Py_NotImplemented, Py_Ellipsis, Py_False, Py_True

Next I will add the thread state argument to every function that needs it.

> I could even imagine that extension methods get an addditional flag that 
> signals that this methods is able to run in the GIL free environment. 
> Older extensions don't have that flag, so Python has to suspend all 
> other threads  while this extension is running. This is perhaps a way to 
> achieve backwards compatibility.

Perhaps, the backwards compatibility is not my top priority. Making 
Python free-threading is. I embedded Python into multithreading web 
server, and found out that it is not ideal for the job.

Harri