bpo-39984: Move pending calls to PyInterpreterState (GH-19066)

If Py_AddPendingCall() is called in a subinterpreter, the function is
now scheduled to be called from the subinterpreter, rather than being
called from the main interpreter.

Each subinterpreter now has its own list of scheduled calls.

* Move pending and eval_breaker fields from _PyRuntimeState.ceval
  to PyInterpreterState.ceval.
* new_interpreter() now calls _PyEval_InitThreads() to create
  pending calls lock.
* Fix Py_AddPendingCall() for subinterpreters. It now calls
  _PyThreadState_GET() which works in a subinterpreter if the
  caller holds the GIL, and only falls back on
  PyGILState_GetThisThreadState() if _PyThreadState_GET()
  returns NULL.

1 files changed, 6 insertions, 4 deletions

diff --git a/Python/ceval_gil.h b/Python/ceval_gil.h
index 3e9f405..b359e3c 100644
--- a/Python/ceval_gil.h
+++ b/Python/ceval_gil.h
@@ -141,7 +141,8 @@ static void recreate_gil(struct _gil_runtime_state *gil)
 }
 
 static void
-drop_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
+drop_gil(struct _ceval_runtime_state *ceval, struct _ceval_state *ceval2,
+         PyThreadState *tstate)
 {
     struct _gil_runtime_state *gil = &ceval->gil;
     if (!_Py_atomic_load_relaxed(&gil->locked)) {
@@ -168,7 +169,7 @@ drop_gil(struct _ceval_runtime_state *ceval, PyThreadState *tstate)
         /* Not switched yet => wait */
         if (((PyThreadState*)_Py_atomic_load_relaxed(&gil->last_holder)) == tstate)
         {
-            RESET_GIL_DROP_REQUEST(ceval);
+            RESET_GIL_DROP_REQUEST(ceval, ceval2);
             /* NOTE: if COND_WAIT does not atomically start waiting when
                releasing the mutex, another thread can run through, take
                the GIL and drop it again, and reset the condition
@@ -230,6 +231,7 @@ take_gil(PyThreadState *tstate)
 
     struct _ceval_runtime_state *ceval = &tstate->interp->runtime->ceval;
     struct _gil_runtime_state *gil = &ceval->gil;
+    struct _ceval_state *ceval2 = &tstate->interp->ceval;
 
     /* Check that _PyEval_InitThreads() was called to create the lock */
     assert(gil_created(gil));
@@ -279,7 +281,7 @@ _ready:
     MUTEX_UNLOCK(gil->switch_mutex);
 #endif
     if (_Py_atomic_load_relaxed(&ceval->gil_drop_request)) {
-        RESET_GIL_DROP_REQUEST(ceval);
+        RESET_GIL_DROP_REQUEST(ceval, ceval2);
     }
 
     int must_exit = tstate_must_exit(tstate);
@@ -299,7 +301,7 @@ _ready:
            This code path can be reached by a daemon thread which was waiting
            in take_gil() while the main thread called
            wait_for_thread_shutdown() from Py_Finalize(). */
-        drop_gil(ceval, tstate);
+        drop_gil(ceval, ceval2, tstate);
         PyThread_exit_thread();
     }