[subinterpreters] Fix pending calls in subinterpreters #84412

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1. vstinner commented on Apr 8, 2020

   

   vstinner

   on Apr 8, 2020

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   Currently, _Py_ThreadCanHandlePendingCalls() only returns true if the current thread is the Python "main thread" (_PyRuntime.main_thread).

   _PyRuntime.main_thread is initialized by _PyRuntime_Initialize().

   The problem is that a subinterpreter can run a separated thread which may not be the "main thread".

   As a consequence, a subinterpreter will not run schedulded pending calls, or it will run them later than it could.

   I modified COMPUTE_EVAL_BREAKER() of ceval.c in bpo-40010: now if tstate->interp->ceval.pending.calls_to_do is true, tstate->interp->ceval.eval_breaker is only set to 1 if _Py_ThreadCanHandlePendingCalls() is true.

   One option would be to allow any thread to run "pending calls".

   Another option is to have one "main thread" per interpreter, rather than having a single "main thread" for all interpreters.

   I made pending calls per-interpreter in bpo-39984.

   In Python 3.7, main_thread variable came from _PyRutimeState.ceval.pending.main_thread. It was moved into _PyRuntimeState by this change:

   commit 5be45a6
   Author: Eric Snow <ericsnowcurrently@gmail.com>
   Date: Fri Mar 8 22:47:07 2019 -0700

   bpo-33608: Minor cleanup related to pending calls. (gh-12247)
   

   --

   _Py_ThreadCanHandleSignals() doesn't have to change: it must only return true for the main thread of the main interpreter. Currently, it's implemented as:

   static inline int
   _Py_ThreadCanHandleSignals(PyThreadState *tstate)
   {
       return (_Py_IsMainThread() && _Py_IsMainInterpreter(tstate));
   }
2. vstinner

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   3.9 (EOL)end of lifeend of life

   on Apr 8, 2020
3. vstinner commented on Apr 8, 2020

   

   vstinner

   on Apr 8, 2020

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   I modified _PyEval_AddPendingCall() to accept interp rather than tstate to fix bpo-40082:

   New changeset b54a99d by Victor Stinner in branch 'master':
   bpo-40082: trip_signal() uses the main interpreter (GH-19441)
   b54a99d
4. vstinner

   added

   topic-subinterpreters

   and removed

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on May 15, 2020
5. vstinner

   changed the title [-]Fix pending calls in subinterpreters[/-] [+][subinterpreters] Fix pending calls in subinterpreters[/+] on May 15, 2020
6. vstinner

   added

   topic-subinterpreters

   and removed

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on May 15, 2020
7. vstinner

   changed the title [-]Fix pending calls in subinterpreters[/-] [+][subinterpreters] Fix pending calls in subinterpreters[/+] on May 15, 2020
8. ezio-melotti

   transferred this issue fromon Apr 10, 2022
9. ezio-melotti

   added this to Subinterpreterson Apr 15, 2022
10. ezio-melotti

    moved this to Todo in Subinterpreterson Apr 15, 2022
11. vstinner commented on Nov 3, 2022

    

    vstinner

    on Nov 3, 2022

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    I don't have the bandwidth to work on this issue, so I just close it.
12. vstinner

    closed this as completedon Nov 3, 2022
13. Repository owner moved this from Todo to Done in Subinterpreterson Nov 3, 2022