bpo-40514: Drop EXPERIMENTAL_ISOLATED_SUBINTERPRETERS (gh-93185)

This was added for bpo-40514 (gh-84694) to test out a per-interpreter GIL. However, it has since proven unnecessary to keep the experiment in the repo. (It can be done as a branch in a fork like normal.) So here we are removing:

* the configure option
* the macro
* the code enabled by the macro

5 files changed, 0 insertions, 102 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 6158524..fdbf0d4 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -352,21 +352,6 @@ _Py_FatalError_TstateNULL(const char *func)
                        "(the current Python thread state is NULL)");
 }
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-int
-_PyEval_ThreadsInitialized(PyInterpreterState *interp)
-{
-    return gil_created(&interp->ceval.gil);
-}
-
-int
-PyEval_ThreadsInitialized(void)
-{
-    // Fatal error if there is no current interpreter
-    PyInterpreterState *interp = PyInterpreterState_Get();
-    return _PyEval_ThreadsInitialized(interp);
-}
-#else
 int
 _PyEval_ThreadsInitialized(_PyRuntimeState *runtime)
 {
@@ -379,25 +364,18 @@ PyEval_ThreadsInitialized(void)
     _PyRuntimeState *runtime = &_PyRuntime;
     return _PyEval_ThreadsInitialized(runtime);
 }
-#endif
 
 PyStatus
 _PyEval_InitGIL(PyThreadState *tstate)
 {
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
     if (!_Py_IsMainInterpreter(tstate->interp)) {
         /* Currently, the GIL is shared by all interpreters,
            and only the main interpreter is responsible to create
            and destroy it. */
         return _PyStatus_OK();
     }
-#endif
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    struct _gil_runtime_state *gil = &tstate->interp->ceval.gil;
-#else
     struct _gil_runtime_state *gil = &tstate->interp->runtime->ceval.gil;
-#endif
     assert(!gil_created(gil));
 
     PyThread_init_thread();
@@ -412,20 +390,14 @@ _PyEval_InitGIL(PyThreadState *tstate)
 void
 _PyEval_FiniGIL(PyInterpreterState *interp)
 {
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
     if (!_Py_IsMainInterpreter(interp)) {
         /* Currently, the GIL is shared by all interpreters,
            and only the main interpreter is responsible to create
            and destroy it. */
         return;
     }
-#endif
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    struct _gil_runtime_state *gil = &interp->ceval.gil;
-#else
     struct _gil_runtime_state *gil = &interp->runtime->ceval.gil;
-#endif
     if (!gil_created(gil)) {
         /* First Py_InitializeFromConfig() call: the GIL doesn't exist
            yet: do nothing. */
@@ -489,13 +461,9 @@ PyEval_AcquireThread(PyThreadState *tstate)
     take_gil(tstate);
 
     struct _gilstate_runtime_state *gilstate = &tstate->interp->runtime->gilstate;
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    (void)_PyThreadState_Swap(gilstate, tstate);
-#else
     if (_PyThreadState_Swap(gilstate, tstate) != NULL) {
         Py_FatalError("non-NULL old thread state");
     }
-#endif
 }
 
 void
@@ -522,11 +490,7 @@ _PyEval_ReInitThreads(PyThreadState *tstate)
 {
     _PyRuntimeState *runtime = tstate->interp->runtime;
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    struct _gil_runtime_state *gil = &tstate->interp->ceval.gil;
-#else
     struct _gil_runtime_state *gil = &runtime->ceval.gil;
-#endif
     if (!gil_created(gil)) {
         return _PyStatus_OK();
     }
@@ -558,21 +522,12 @@ PyThreadState *
 PyEval_SaveThread(void)
 {
     _PyRuntimeState *runtime = &_PyRuntime;
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    PyThreadState *old_tstate = _PyThreadState_GET();
-    PyThreadState *tstate = _PyThreadState_Swap(&runtime->gilstate, old_tstate);
-#else
     PyThreadState *tstate = _PyThreadState_Swap(&runtime->gilstate, NULL);
-#endif
     _Py_EnsureTstateNotNULL(tstate);
 
     struct _ceval_runtime_state *ceval = &runtime->ceval;
     struct _ceval_state *ceval2 = &tstate->interp->ceval;
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    assert(gil_created(&ceval2->gil));
-#else
     assert(gil_created(&ceval->gil));
-#endif
     drop_gil(ceval, ceval2, tstate);
     return tstate;
 }
@@ -836,9 +791,7 @@ Py_MakePendingCalls(void)
 void
 _PyEval_InitRuntimeState(struct _ceval_runtime_state *ceval)
 {
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
     _gil_initialize(&ceval->gil);
-#endif
 }
 
 void
@@ -848,10 +801,6 @@ _PyEval_InitState(struct _ceval_state *ceval, PyThread_type_lock pending_lock)
     assert(pending->lock == NULL);
 
     pending->lock = pending_lock;
-
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    _gil_initialize(&ceval->gil);
-#endif
 }
 
 void
@@ -1267,13 +1216,9 @@ eval_frame_handle_pending(PyThreadState *tstate)
 
         take_gil(tstate);
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-        (void)_PyThreadState_Swap(&runtime->gilstate, tstate);
-#else
         if (_PyThreadState_Swap(&runtime->gilstate, tstate) != NULL) {
             Py_FatalError("orphan tstate");
         }
-#endif
     }
 
     /* Check for asynchronous exception. */
diff --git a/Python/ceval_gil.h b/Python/ceval_gil.h
index 9b8b432..1b2dc7f 100644
--- a/Python/ceval_gil.h
+++ b/Python/ceval_gil.h
@@ -144,11 +144,7 @@ static void
 drop_gil(struct _ceval_runtime_state *ceval, struct _ceval_state *ceval2,
          PyThreadState *tstate)
 {
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    struct _gil_runtime_state *gil = &ceval2->gil;
-#else
     struct _gil_runtime_state *gil = &ceval->gil;
-#endif
     if (!_Py_atomic_load_relaxed(&gil->locked)) {
         Py_FatalError("drop_gil: GIL is not locked");
     }
@@ -232,11 +228,7 @@ take_gil(PyThreadState *tstate)
     PyInterpreterState *interp = tstate->interp;
     struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
     struct _ceval_state *ceval2 = &interp->ceval;
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    struct _gil_runtime_state *gil = &ceval2->gil;
-#else
     struct _gil_runtime_state *gil = &ceval->gil;
-#endif
 
     /* Check that _PyEval_InitThreads() was called to create the lock */
     assert(gil_created(gil));
@@ -328,22 +320,12 @@ _ready:
 
 void _PyEval_SetSwitchInterval(unsigned long microseconds)
 {
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    PyInterpreterState *interp = PyInterpreterState_Get();
-    struct _gil_runtime_state *gil = &interp->ceval.gil;
-#else
     struct _gil_runtime_state *gil = &_PyRuntime.ceval.gil;
-#endif
     gil->interval = microseconds;
 }
 
 unsigned long _PyEval_GetSwitchInterval()
 {
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    PyInterpreterState *interp = PyInterpreterState_Get();
-    struct _gil_runtime_state *gil = &interp->ceval.gil;
-#else
     struct _gil_runtime_state *gil = &_PyRuntime.ceval.gil;
-#endif
     return gil->interval;
 }
diff --git a/Python/preconfig.c b/Python/preconfig.c
index e7125cd..c30c758 100644
--- a/Python/preconfig.c
+++ b/Python/preconfig.c
@@ -294,17 +294,7 @@ _PyPreConfig_InitCompatConfig(PyPreConfig *config)
     config->coerce_c_locale_warn = 0;
 
     config->dev_mode = -1;
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    /* bpo-40512: pymalloc is not compatible with subinterpreters,
-       force usage of libc malloc() which is thread-safe. */
-#ifdef Py_DEBUG
-    config->allocator = PYMEM_ALLOCATOR_MALLOC_DEBUG;
-#else
-    config->allocator = PYMEM_ALLOCATOR_MALLOC;
-#endif
-#else
     config->allocator = PYMEM_ALLOCATOR_NOT_SET;
-#endif
 #ifdef MS_WINDOWS
     config->legacy_windows_fs_encoding = -1;
 #endif
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 42a0581..31a358f 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1981,12 +1981,10 @@ new_interpreter(PyThreadState **tstate_p, int isolated_subinterpreter)
 
     /* Copy the current interpreter config into the new interpreter */
     const PyConfig *config;
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
     if (save_tstate != NULL) {
         config = _PyInterpreterState_GetConfig(save_tstate->interp);
     }
     else
-#endif
     {
         /* No current thread state, copy from the main interpreter */
         PyInterpreterState *main_interp = _PyInterpreterState_Main();
diff --git a/Python/pystate.c b/Python/pystate.c
index 3e28a6a..df56c05 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -1165,14 +1165,6 @@ _PyThreadState_DeleteExcept(_PyRuntimeState *runtime, PyThreadState *tstate)
 }
 
 
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-PyThreadState*
-_PyThreadState_GetTSS(void) {
-    return PyThread_tss_get(&_PyRuntime.gilstate.autoTSSkey);
-}
-#endif
-
-
 PyThreadState *
 _PyThreadState_UncheckedGet(void)
 {
@@ -1192,11 +1184,7 @@ PyThreadState_Get(void)
 PyThreadState *
 _PyThreadState_Swap(struct _gilstate_runtime_state *gilstate, PyThreadState *newts)
 {
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    PyThreadState *oldts = _PyThreadState_GetTSS();
-#else
     PyThreadState *oldts = _PyRuntimeGILState_GetThreadState(gilstate);
-#endif
 
     _PyRuntimeGILState_SetThreadState(gilstate, newts);
     /* It should not be possible for more than one thread state
@@ -1215,9 +1203,6 @@ _PyThreadState_Swap(struct _gilstate_runtime_state *gilstate, PyThreadState *new
         errno = err;
     }
 #endif
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-    PyThread_tss_set(&gilstate->autoTSSkey, newts);
-#endif
     return oldts;
 }
 
@@ -1665,9 +1650,7 @@ PyGILState_Ensure(void)
 
     /* Ensure that _PyEval_InitThreads() and _PyGILState_Init() have been
        called by Py_Initialize() */
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
     assert(_PyEval_ThreadsInitialized(runtime));
-#endif
     assert(gilstate->autoInterpreterState);
 
     PyThreadState *tcur = (PyThreadState *)PyThread_tss_get(&gilstate->autoTSSkey);