bpo-45953: Statically allocate the main interpreter (and initial thread state). (gh-29883)

Previously, the main interpreter was allocated on the heap during runtime initialization.  Here we instead embed it into _PyRuntimeState, which means it is statically allocated as part of the _PyRuntime global.  The same goes for the initial thread state (of each interpreter, including the main one).  Consequently there are fewer allocations during runtime/interpreter init, fewer possible failures, and better memory locality.

FYI, this also helps efforts to consolidate globals, which in turns helps work on subinterpreter isolation.

https://bugs.python.org/issue45953

1 files changed, 9 insertions, 1 deletions

diff --git a/Include/cpython/pystate.h b/Include/cpython/pystate.h
index c37123c..bcb1bb2 100644
--- a/Include/cpython/pystate.h
+++ b/Include/cpython/pystate.h
@@ -2,6 +2,9 @@
 #  error "this header file must not be included directly"
 #endif
 
+#include <stdbool.h>
+
+
 PyAPI_FUNC(int) _PyInterpreterState_RequiresIDRef(PyInterpreterState *);
 PyAPI_FUNC(void) _PyInterpreterState_RequireIDRef(PyInterpreterState *, int);
 
@@ -83,6 +86,9 @@ struct _ts {
        after allocation. */
     int _initialized;
 
+    /* Was this thread state statically allocated? */
+    bool _static;
+
     int recursion_remaining;
     int recursion_limit;
     int recursion_headroom; /* Allow 50 more calls to handle any errors. */
@@ -175,9 +181,11 @@ struct _ts {
     PyObject **datastack_top;
     PyObject **datastack_limit;
     /* XXX signal handlers should also be here */
-
 };
 
+
+/* other API */
+
 // Alias for backward compatibility with Python 3.8
 #define _PyInterpreterState_Get PyInterpreterState_Get