Обсуждение: PL/Python initialization cleanup

As I was working through steps to make PL/Python more thread-safe, I 
noticed that the initialization code of PL/Python is pretty messy.  I 
think some of this has grown while both Python 2 and 3 were supported, 
because they required different initialization steps, and we had some 
defenses against accidentally running both at the same time.  But that 
is over, and right now a lot of this doesn't make sense anymore.  For 
example, the function PLy_init_interp() said "Initialize the Python 
interpreter ..." but it didn't actually do this, and PLy_init_plpy() 
said "initialize plpy module" but it didn't do that either (or at least 
they used the term "initialize" in non-standard ways).

Here are some patches to clean this up.  After this change, all the 
global initialization is called directly from _PG_init(), and the plpy 
module initialization is all called from its registered initialization 
function PyInit_plpy().  (For the thread-safety job, the plpy module 
initialization will need to be rewritten using a different API.  That's 
why I'm keen to have it clearly separated.)  I also tried to add more 
comments and make existing comments more precise.  There was also some 
apparently obsolete or redundant code that could be deleted.

Surely, all of this will need some more rounds of careful scrutiny, but 
I think the overall code arrangement is correct and an improvement.

> On Dec 31, 2025, at 16:47, Peter Eisentraut <peter@eisentraut.org> wrote:
>
> As I was working through steps to make PL/Python more thread-safe, I noticed that the initialization code of
PL/Pythonis pretty messy.  I think some of this has grown while both Python 2 and 3 were supported, because they
requireddifferent initialization steps, and we had some defenses against accidentally running both at the same time.
Butthat is over, and right now a lot of this doesn't make sense anymore.  For example, the function PLy_init_interp()
said"Initialize the Python interpreter ..." but it didn't actually do this, and PLy_init_plpy() said "initialize plpy
module"but it didn't do that either (or at least they used the term "initialize" in non-standard ways). 
>
> Here are some patches to clean this up.  After this change, all the global initialization is called directly from
_PG_init(),and the plpy module initialization is all called from its registered initialization function PyInit_plpy().
(Forthe thread-safety job, the plpy module initialization will need to be rewritten using a different API.  That's why
I'mkeen to have it clearly separated.)  I also tried to add more comments and make existing comments more precise.
Therewas also some apparently obsolete or redundant code that could be deleted. 
>
> Surely, all of this will need some more rounds of careful scrutiny, but I think the overall code arrangement is
correctand an improvement. 
>
<v1-0001-plpython-Remove-commented-out-code.patch><v1-0002-plpython-Clean-up-PyModule_AddObject-uses.patch><v1-0003-plpython-Remove-duplicate-PyModule_Create.patch><v1-0004-plpython-Streamline-initialization.patch>

I just did an eyeball review. Overall looks good to me. The cleanup, as explained in the patch email, makes sense to
me.Only a nit comment on 0002: 

1 - 0002
```
+    if (PyModule_AddObject(mod, modname, exc) < 0)
+    {
+        Py_XDECREF(exc);
+        PLy_elog(ERROR, "could not add exceptions %s", name);
+    }
```

Plural “exceptions” is a little confusing. What about “could not add exception object”?

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/