Update Python from 3.11.8 to 3.12.2

1 files changed, 266 insertions, 2052 deletions

diff --git a/contrib/tools/python3/src/Modules/_xxsubinterpretersmodule.c b/contrib/tools/python3/src/Modules/_xxsubinterpretersmodule.c
index e5b96be8f68..c0958c65dd0 100644
--- a/contrib/tools/python3/src/Modules/_xxsubinterpretersmodule.c
+++ b/contrib/tools/python3/src/Modules/_xxsubinterpretersmodule.c
@@ -1,24 +1,29 @@
 
 /* interpreters module */
 /* low-level access to interpreter primitives */
+
 #ifndef Py_BUILD_CORE_BUILTIN
 #  define Py_BUILD_CORE_MODULE 1
 #endif
 
 #include "Python.h"
-#include "pycore_frame.h"
-#include "pycore_pystate.h"       // _PyThreadState_GET()
-#include "pycore_interpreteridobject.h"
+#include "pycore_initconfig.h"    // _PyErr_SetFromPyStatus()
+#include "pycore_pyerrors.h"      // _PyErr_ChainExceptions1()
+#include "pycore_pystate.h"       // _PyInterpreterState_SetRunningMain()
+#include "interpreteridobject.h"
+
 
+#define MODULE_NAME "_xxsubinterpreters"
 
-static char *
+
+static const char *
 _copy_raw_string(PyObject *strobj)
 {
     const char *str = PyUnicode_AsUTF8(strobj);
     if (str == NULL) {
         return NULL;
     }
-    char *copied = PyMem_Malloc(strlen(str)+1);
+    char *copied = PyMem_RawMalloc(strlen(str)+1);
     if (copied == NULL) {
         PyErr_NoMemory();
         return NULL;
@@ -28,18 +33,87 @@ _copy_raw_string(PyObject *strobj)
 }
 
 static PyInterpreterState *
-_get_current(void)
+_get_current_interp(void)
 {
     // PyInterpreterState_Get() aborts if lookup fails, so don't need
     // to check the result for NULL.
     return PyInterpreterState_Get();
 }
 
+static PyObject *
+add_new_exception(PyObject *mod, const char *name, PyObject *base)
+{
+    assert(!PyObject_HasAttrString(mod, name));
+    PyObject *exctype = PyErr_NewException(name, base, NULL);
+    if (exctype == NULL) {
+        return NULL;
+    }
+    int res = PyModule_AddType(mod, (PyTypeObject *)exctype);
+    if (res < 0) {
+        Py_DECREF(exctype);
+        return NULL;
+    }
+    return exctype;
+}
+
+#define ADD_NEW_EXCEPTION(MOD, NAME, BASE) \
+    add_new_exception(MOD, MODULE_NAME "." Py_STRINGIFY(NAME), BASE)
+
+static int
+_release_xid_data(_PyCrossInterpreterData *data)
+{
+    PyObject *exc = PyErr_GetRaisedException();
+    int res = _PyCrossInterpreterData_Release(data);
+    if (res < 0) {
+        /* The owning interpreter is already destroyed. */
+        _PyCrossInterpreterData_Clear(NULL, data);
+        // XXX Emit a warning?
+        PyErr_Clear();
+    }
+    PyErr_SetRaisedException(exc);
+    return res;
+}
+
+
+/* module state *************************************************************/
+
+typedef struct {
+    /* exceptions */
+    PyObject *RunFailedError;
+} module_state;
+
+static inline module_state *
+get_module_state(PyObject *mod)
+{
+    assert(mod != NULL);
+    module_state *state = PyModule_GetState(mod);
+    assert(state != NULL);
+    return state;
+}
+
+static int
+traverse_module_state(module_state *state, visitproc visit, void *arg)
+{
+    /* exceptions */
+    Py_VISIT(state->RunFailedError);
+
+    return 0;
+}
+
+static int
+clear_module_state(module_state *state)
+{
+    /* exceptions */
+    Py_CLEAR(state->RunFailedError);
+
+    return 0;
+}
+
 
 /* data-sharing-specific code ***********************************************/
 
 struct _sharednsitem {
-    char *name;
+    const char *name;
     _PyCrossInterpreterData data;
 };
 
@@ -63,10 +137,10 @@ static void
 _sharednsitem_clear(struct _sharednsitem *item)
 {
     if (item->name != NULL) {
-        PyMem_Free(item->name);
+        PyMem_RawFree((void *)item->name);
         item->name = NULL;
     }
-    _PyCrossInterpreterData_Release(&item->data);
+    (void)_release_xid_data(&item->data);
 }
 
 static int
@@ -95,16 +169,16 @@ typedef struct _sharedns {
 static _sharedns *
 _sharedns_new(Py_ssize_t len)
 {
-    _sharedns *shared = PyMem_NEW(_sharedns, 1);
+    _sharedns *shared = PyMem_RawCalloc(sizeof(_sharedns), 1);
     if (shared == NULL) {
         PyErr_NoMemory();
         return NULL;
     }
     shared->len = len;
-    shared->items = PyMem_NEW(struct _sharednsitem, len);
+    shared->items = PyMem_RawCalloc(sizeof(struct _sharednsitem), len);
     if (shared->items == NULL) {
         PyErr_NoMemory();
-        PyMem_Free(shared);
+        PyMem_RawFree(shared);
         return NULL;
     }
     return shared;
@@ -116,8 +190,8 @@ _sharedns_free(_sharedns *shared)
     for (Py_ssize_t i=0; i < shared->len; i++) {
         _sharednsitem_clear(&shared->items[i]);
     }
-    PyMem_Free(shared->items);
-    PyMem_Free(shared);
+    PyMem_RawFree(shared->items);
+    PyMem_RawFree(shared);
 }
 
 static _sharedns *
@@ -169,96 +243,74 @@ _sharedns_apply(_sharedns *shared, PyObject *ns)
 // of the exception in the calling interpreter.
 
 typedef struct _sharedexception {
-    char *name;
-    char *msg;
+    const char *name;
+    const char *msg;
 } _sharedexception;
 
-static _sharedexception *
-_sharedexception_new(void)
-{
-    _sharedexception *err = PyMem_NEW(_sharedexception, 1);
-    if (err == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    err->name = NULL;
-    err->msg = NULL;
-    return err;
-}
+static const struct _sharedexception no_exception = {
+    .name = NULL,
+    .msg = NULL,
+};
 
 static void
 _sharedexception_clear(_sharedexception *exc)
 {
     if (exc->name != NULL) {
-        PyMem_Free(exc->name);
+        PyMem_RawFree((void *)exc->name);
     }
     if (exc->msg != NULL) {
-        PyMem_Free(exc->msg);
+        PyMem_RawFree((void *)exc->msg);
     }
 }
 
-static void
-_sharedexception_free(_sharedexception *exc)
-{
-    _sharedexception_clear(exc);
-    PyMem_Free(exc);
-}
-
-static _sharedexception *
-_sharedexception_bind(PyObject *exctype, PyObject *exc, PyObject *tb)
+static const char *
+_sharedexception_bind(PyObject *exc, _sharedexception *sharedexc)
 {
-    assert(exctype != NULL);
-    char *failure = NULL;
+    assert(exc != NULL);
+    const char *failure = NULL;
 
-    _sharedexception *err = _sharedexception_new();
-    if (err == NULL) {
-        goto finally;
-    }
-
-    PyObject *name = PyUnicode_FromFormat("%S", exctype);
-    if (name == NULL) {
+    PyObject *nameobj = PyUnicode_FromFormat("%S", Py_TYPE(exc));
+    if (nameobj == NULL) {
         failure = "unable to format exception type name";
-        goto finally;
+        goto error;
     }
-    err->name = _copy_raw_string(name);
-    Py_DECREF(name);
-    if (err->name == NULL) {
+    sharedexc->name = _copy_raw_string(nameobj);
+    Py_DECREF(nameobj);
+    if (sharedexc->name == NULL) {
         if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
             failure = "out of memory copying exception type name";
         } else {
             failure = "unable to encode and copy exception type name";
         }
-        goto finally;
+        goto error;
     }
 
     if (exc != NULL) {
-        PyObject *msg = PyUnicode_FromFormat("%S", exc);
-        if (msg == NULL) {
+        PyObject *msgobj = PyUnicode_FromFormat("%S", exc);
+        if (msgobj == NULL) {
             failure = "unable to format exception message";
-            goto finally;
+            goto error;
         }
-        err->msg = _copy_raw_string(msg);
-        Py_DECREF(msg);
-        if (err->msg == NULL) {
+        sharedexc->msg = _copy_raw_string(msgobj);
+        Py_DECREF(msgobj);
+        if (sharedexc->msg == NULL) {
             if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
                 failure = "out of memory copying exception message";
             } else {
                 failure = "unable to encode and copy exception message";
             }
-            goto finally;
+            goto error;
         }
     }
 
-finally:
-    if (failure != NULL) {
-        PyErr_Clear();
-        if (err->name != NULL) {
-            PyMem_Free(err->name);
-            err->name = NULL;
-        }
-        err->msg = failure;
-    }
-    return err;
+    return NULL;
+
+error:
+    assert(failure != NULL);
+    PyErr_Clear();
+    _sharedexception_clear(sharedexc);
+    *sharedexc = no_exception;
+    return failure;
 }
 
 static void
@@ -281,1592 +333,42 @@ _sharedexception_apply(_sharedexception *exc, PyObject *wrapperclass)
 }
 
 
-/* channel-specific code ****************************************************/
-
-#define CHANNEL_SEND 1
-#define CHANNEL_BOTH 0
-#define CHANNEL_RECV -1
-
-static PyObject *ChannelError;
-static PyObject *ChannelNotFoundError;
-static PyObject *ChannelClosedError;
-static PyObject *ChannelEmptyError;
-static PyObject *ChannelNotEmptyError;
-
-static int
-channel_exceptions_init(PyObject *ns)
-{
-    // XXX Move the exceptions into per-module memory?
-
-    // A channel-related operation failed.
-    ChannelError = PyErr_NewException("_xxsubinterpreters.ChannelError",
-                                      PyExc_RuntimeError, NULL);
-    if (ChannelError == NULL) {
-        return -1;
-    }
-    if (PyDict_SetItemString(ns, "ChannelError", ChannelError) != 0) {
-        return -1;
-    }
-
-    // An operation tried to use a channel that doesn't exist.
-    ChannelNotFoundError = PyErr_NewException(
-            "_xxsubinterpreters.ChannelNotFoundError", ChannelError, NULL);
-    if (ChannelNotFoundError == NULL) {
-        return -1;
-    }
-    if (PyDict_SetItemString(ns, "ChannelNotFoundError", ChannelNotFoundError) != 0) {
-        return -1;
-    }
-
-    // An operation tried to use a closed channel.
-    ChannelClosedError = PyErr_NewException(
-            "_xxsubinterpreters.ChannelClosedError", ChannelError, NULL);
-    if (ChannelClosedError == NULL) {
-        return -1;
-    }
-    if (PyDict_SetItemString(ns, "ChannelClosedError", ChannelClosedError) != 0) {
-        return -1;
-    }
-
-    // An operation tried to pop from an empty channel.
-    ChannelEmptyError = PyErr_NewException(
-            "_xxsubinterpreters.ChannelEmptyError", ChannelError, NULL);
-    if (ChannelEmptyError == NULL) {
-        return -1;
-    }
-    if (PyDict_SetItemString(ns, "ChannelEmptyError", ChannelEmptyError) != 0) {
-        return -1;
-    }
-
-    // An operation tried to close a non-empty channel.
-    ChannelNotEmptyError = PyErr_NewException(
-            "_xxsubinterpreters.ChannelNotEmptyError", ChannelError, NULL);
-    if (ChannelNotEmptyError == NULL) {
-        return -1;
-    }
-    if (PyDict_SetItemString(ns, "ChannelNotEmptyError", ChannelNotEmptyError) != 0) {
-        return -1;
-    }
-
-    return 0;
-}
-
-/* the channel queue */
-
-struct _channelitem;
-
-typedef struct _channelitem {
-    _PyCrossInterpreterData *data;
-    struct _channelitem *next;
-} _channelitem;
-
-static _channelitem *
-_channelitem_new(void)
-{
-    _channelitem *item = PyMem_NEW(_channelitem, 1);
-    if (item == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    item->data = NULL;
-    item->next = NULL;
-    return item;
-}
-
-static void
-_channelitem_clear(_channelitem *item)
-{
-    if (item->data != NULL) {
-        _PyCrossInterpreterData_Release(item->data);
-        PyMem_Free(item->data);
-        item->data = NULL;
-    }
-    item->next = NULL;
-}
-
-static void
-_channelitem_free(_channelitem *item)
-{
-    _channelitem_clear(item);
-    PyMem_Free(item);
-}
-
-static void
-_channelitem_free_all(_channelitem *item)
-{
-    while (item != NULL) {
-        _channelitem *last = item;
-        item = item->next;
-        _channelitem_free(last);
-    }
-}
-
-static _PyCrossInterpreterData *
-_channelitem_popped(_channelitem *item)
-{
-    _PyCrossInterpreterData *data = item->data;
-    item->data = NULL;
-    _channelitem_free(item);
-    return data;
-}
-
-typedef struct _channelqueue {
-    int64_t count;
-    _channelitem *first;
-    _channelitem *last;
-} _channelqueue;
-
-static _channelqueue *
-_channelqueue_new(void)
-{
-    _channelqueue *queue = PyMem_NEW(_channelqueue, 1);
-    if (queue == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    queue->count = 0;
-    queue->first = NULL;
-    queue->last = NULL;
-    return queue;
-}
-
-static void
-_channelqueue_clear(_channelqueue *queue)
-{
-    _channelitem_free_all(queue->first);
-    queue->count = 0;
-    queue->first = NULL;
-    queue->last = NULL;
-}
-
-static void
-_channelqueue_free(_channelqueue *queue)
-{
-    _channelqueue_clear(queue);
-    PyMem_Free(queue);
-}
-
-static int
-_channelqueue_put(_channelqueue *queue, _PyCrossInterpreterData *data)
-{
-    _channelitem *item = _channelitem_new();
-    if (item == NULL) {
-        return -1;
-    }
-    item->data = data;
-
-    queue->count += 1;
-    if (queue->first == NULL) {
-        queue->first = item;
-    }
-    else {
-        queue->last->next = item;
-    }
-    queue->last = item;
-    return 0;
-}
-
-static _PyCrossInterpreterData *
-_channelqueue_get(_channelqueue *queue)
-{
-    _channelitem *item = queue->first;
-    if (item == NULL) {
-        return NULL;
-    }
-    queue->first = item->next;
-    if (queue->last == item) {
-        queue->last = NULL;
-    }
-    queue->count -= 1;
-
-    return _channelitem_popped(item);
-}
-
-/* channel-interpreter associations */
-
-struct _channelend;
-
-typedef struct _channelend {
-    struct _channelend *next;
-    int64_t interp;
-    int open;
-} _channelend;
-
-static _channelend *
-_channelend_new(int64_t interp)
-{
-    _channelend *end = PyMem_NEW(_channelend, 1);
-    if (end == NULL) {
-        PyErr_NoMemory();
-        return NULL;
-    }
-    end->next = NULL;
-    end->interp = interp;
-    end->open = 1;
-    return end;
-}
-
-static void
-_channelend_free(_channelend *end)
-{
-    PyMem_Free(end);
-}
-
-static void
-_channelend_free_all(_channelend *end)
-{
-    while (end != NULL) {
-        _channelend *last = end;
-        end = end->next;
-        _channelend_free(last);
-    }
-}
-
-static _channelend *
-_channelend_find(_channelend *first, int64_t interp, _channelend **pprev)
-{
-    _channelend *prev = NULL;
-    _channelend *end = first;
-    while (end != NULL) {
-        if (end->interp == interp) {
-            break;
-        }
-        prev = end;
-        end = end->next;
-    }
-    if (pprev != NULL) {
-        *pprev = prev;
-    }
-    return end;
-}
-
-typedef struct _channelassociations {
-    // Note that the list entries are never removed for interpreter
-    // for which the channel is closed.  This should not be a problem in
-    // practice.  Also, a channel isn't automatically closed when an
-    // interpreter is destroyed.
-    int64_t numsendopen;
-    int64_t numrecvopen;
-    _channelend *send;
-    _channelend *recv;
-} _channelends;
-
-static _channelends *
-_channelends_new(void)
-{
-    _channelends *ends = PyMem_NEW(_channelends, 1);
-    if (ends== NULL) {
-        return NULL;
-    }
-    ends->numsendopen = 0;
-    ends->numrecvopen = 0;
-    ends->send = NULL;
-    ends->recv = NULL;
-    return ends;
-}
-
-static void
-_channelends_clear(_channelends *ends)
-{
-    _channelend_free_all(ends->send);
-    ends->send = NULL;
-    ends->numsendopen = 0;
-
-    _channelend_free_all(ends->recv);
-    ends->recv = NULL;
-    ends->numrecvopen = 0;
-}
-
-static void
-_channelends_free(_channelends *ends)
-{
-    _channelends_clear(ends);
-    PyMem_Free(ends);
-}
-
-static _channelend *
-_channelends_add(_channelends *ends, _channelend *prev, int64_t interp,
-                 int send)
-{
-    _channelend *end = _channelend_new(interp);
-    if (end == NULL) {
-        return NULL;
-    }
-
-    if (prev == NULL) {
-        if (send) {
-            ends->send = end;
-        }
-        else {
-            ends->recv = end;
-        }
-    }
-    else {
-        prev->next = end;
-    }
-    if (send) {
-        ends->numsendopen += 1;
-    }
-    else {
-        ends->numrecvopen += 1;
-    }
-    return end;
-}
-
-static int
-_channelends_associate(_channelends *ends, int64_t interp, int send)
-{
-    _channelend *prev;
-    _channelend *end = _channelend_find(send ? ends->send : ends->recv,
-                                        interp, &prev);
-    if (end != NULL) {
-        if (!end->open) {
-            PyErr_SetString(ChannelClosedError, "channel already closed");
-            return -1;
-        }
-        // already associated
-        return 0;
-    }
-    if (_channelends_add(ends, prev, interp, send) == NULL) {
-        return -1;
-    }
-    return 0;
-}
-
-static int
-_channelends_is_open(_channelends *ends)
-{
-    if (ends->numsendopen != 0 || ends->numrecvopen != 0) {
-        return 1;
-    }
-    if (ends->send == NULL && ends->recv == NULL) {
-        return 1;
-    }
-    return 0;
-}
-
-static void
-_channelends_close_end(_channelends *ends, _channelend *end, int send)
-{
-    end->open = 0;
-    if (send) {
-        ends->numsendopen -= 1;
-    }
-    else {
-        ends->numrecvopen -= 1;
-    }
-}
-
-static int
-_channelends_close_interpreter(_channelends *ends, int64_t interp, int which)
-{
-    _channelend *prev;
-    _channelend *end;
-    if (which >= 0) {  // send/both
-        end = _channelend_find(ends->send, interp, &prev);
-        if (end == NULL) {
-            // never associated so add it
-            end = _channelends_add(ends, prev, interp, 1);
-            if (end == NULL) {
-                return -1;
-            }
-        }
-        _channelends_close_end(ends, end, 1);
-    }
-    if (which <= 0) {  // recv/both
-        end = _channelend_find(ends->recv, interp, &prev);
-        if (end == NULL) {
-            // never associated so add it
-            end = _channelends_add(ends, prev, interp, 0);
-            if (end == NULL) {
-                return -1;
-            }
-        }
-        _channelends_close_end(ends, end, 0);
-    }
-    return 0;
-}
-
-static void
-_channelends_close_all(_channelends *ends, int which, int force)
-{
-    // XXX Handle the ends.
-    // XXX Handle force is True.
-
-    // Ensure all the "send"-associated interpreters are closed.
-    _channelend *end;
-    for (end = ends->send; end != NULL; end = end->next) {
-        _channelends_close_end(ends, end, 1);
-    }
-
-    // Ensure all the "recv"-associated interpreters are closed.
-    for (end = ends->recv; end != NULL; end = end->next) {
-        _channelends_close_end(ends, end, 0);
-    }
-}
-
-/* channels */
-
-struct _channel;
-struct _channel_closing;
-static void _channel_clear_closing(struct _channel *);
-static void _channel_finish_closing(struct _channel *);
-
-typedef struct _channel {
-    PyThread_type_lock mutex;
-    _channelqueue *queue;
-    _channelends *ends;
-    int open;
-    struct _channel_closing *closing;
-} _PyChannelState;
-
-static _PyChannelState *
-_channel_new(void)
-{
-    _PyChannelState *chan = PyMem_NEW(_PyChannelState, 1);
-    if (chan == NULL) {
-        return NULL;
-    }
-    chan->mutex = PyThread_allocate_lock();
-    if (chan->mutex == NULL) {
-        PyMem_Free(chan);
-        PyErr_SetString(ChannelError,
-                        "can't initialize mutex for new channel");
-        return NULL;
-    }
-    chan->queue = _channelqueue_new();
-    if (chan->queue == NULL) {
-        PyMem_Free(chan);
-        return NULL;
-    }
-    chan->ends = _channelends_new();
-    if (chan->ends == NULL) {
-        _channelqueue_free(chan->queue);
-        PyMem_Free(chan);
-        return NULL;
-    }
-    chan->open = 1;
-    chan->closing = NULL;
-    return chan;
-}
-
-static void
-_channel_free(_PyChannelState *chan)
-{
-    _channel_clear_closing(chan);
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-    _channelqueue_free(chan->queue);
-    _channelends_free(chan->ends);
-    PyThread_release_lock(chan->mutex);
-
-    PyThread_free_lock(chan->mutex);
-    PyMem_Free(chan);
-}
-
-static int
-_channel_add(_PyChannelState *chan, int64_t interp,
-             _PyCrossInterpreterData *data)
-{
-    int res = -1;
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-
-    if (!chan->open) {
-        PyErr_SetString(ChannelClosedError, "channel closed");
-        goto done;
-    }
-    if (_channelends_associate(chan->ends, interp, 1) != 0) {
-        goto done;
-    }
-
-    if (_channelqueue_put(chan->queue, data) != 0) {
-        goto done;
-    }
-
-    res = 0;
-done:
-    PyThread_release_lock(chan->mutex);
-    return res;
-}
-
-static _PyCrossInterpreterData *
-_channel_next(_PyChannelState *chan, int64_t interp)
-{
-    _PyCrossInterpreterData *data = NULL;
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-
-    if (!chan->open) {
-        PyErr_SetString(ChannelClosedError, "channel closed");
-        goto done;
-    }
-    if (_channelends_associate(chan->ends, interp, 0) != 0) {
-        goto done;
-    }
-
-    data = _channelqueue_get(chan->queue);
-    if (data == NULL && !PyErr_Occurred() && chan->closing != NULL) {
-        chan->open = 0;
-    }
-
-done:
-    PyThread_release_lock(chan->mutex);
-    if (chan->queue->count == 0) {
-        _channel_finish_closing(chan);
-    }
-    return data;
-}
-
-static int
-_channel_close_interpreter(_PyChannelState *chan, int64_t interp, int end)
-{
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-
-    int res = -1;
-    if (!chan->open) {
-        PyErr_SetString(ChannelClosedError, "channel already closed");
-        goto done;
-    }
-
-    if (_channelends_close_interpreter(chan->ends, interp, end) != 0) {
-        goto done;
-    }
-    chan->open = _channelends_is_open(chan->ends);
-
-    res = 0;
-done:
-    PyThread_release_lock(chan->mutex);
-    return res;
-}
-
-static int
-_channel_close_all(_PyChannelState *chan, int end, int force)
-{
-    int res = -1;
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-
-    if (!chan->open) {
-        PyErr_SetString(ChannelClosedError, "channel already closed");
-        goto done;
-    }
-
-    if (!force && chan->queue->count > 0) {
-        PyErr_SetString(ChannelNotEmptyError,
-                        "may not be closed if not empty (try force=True)");
-        goto done;
-    }
-
-    chan->open = 0;
-
-    // We *could* also just leave these in place, since we've marked
-    // the channel as closed already.
-    _channelends_close_all(chan->ends, end, force);
-
-    res = 0;
-done:
-    PyThread_release_lock(chan->mutex);
-    return res;
-}
-
-/* the set of channels */
-
-struct _channelref;
-
-typedef struct _channelref {
-    int64_t id;
-    _PyChannelState *chan;
-    struct _channelref *next;
-    Py_ssize_t objcount;
-} _channelref;
-
-static _channelref *
-_channelref_new(int64_t id, _PyChannelState *chan)
-{
-    _channelref *ref = PyMem_NEW(_channelref, 1);
-    if (ref == NULL) {
-        return NULL;
-    }
-    ref->id = id;
-    ref->chan = chan;
-    ref->next = NULL;
-    ref->objcount = 0;
-    return ref;
-}
-
-//static void
-//_channelref_clear(_channelref *ref)
-//{
-//    ref->id = -1;
-//    ref->chan = NULL;
-//    ref->next = NULL;
-//    ref->objcount = 0;
-//}
-
-static void
-_channelref_free(_channelref *ref)
-{
-    if (ref->chan != NULL) {
-        _channel_clear_closing(ref->chan);
-    }
-    //_channelref_clear(ref);
-    PyMem_Free(ref);
-}
-
-static _channelref *
-_channelref_find(_channelref *first, int64_t id, _channelref **pprev)
-{
-    _channelref *prev = NULL;
-    _channelref *ref = first;
-    while (ref != NULL) {
-        if (ref->id == id) {
-            break;
-        }
-        prev = ref;
-        ref = ref->next;
-    }
-    if (pprev != NULL) {
-        *pprev = prev;
-    }
-    return ref;
-}
-
-typedef struct _channels {
-    PyThread_type_lock mutex;
-    _channelref *head;
-    int64_t numopen;
-    int64_t next_id;
-} _channels;
-
-static int
-_channels_init(_channels *channels)
-{
-    if (channels->mutex == NULL) {
-        channels->mutex = PyThread_allocate_lock();
-        if (channels->mutex == NULL) {
-            PyErr_SetString(ChannelError,
-                            "can't initialize mutex for channel management");
-            return -1;
-        }
-    }
-    channels->head = NULL;
-    channels->numopen = 0;
-    channels->next_id = 0;
-    return 0;
-}
-
-static int64_t
-_channels_next_id(_channels *channels)  // needs lock
-{
-    int64_t id = channels->next_id;
-    if (id < 0) {
-        /* overflow */
-        PyErr_SetString(ChannelError,
-                        "failed to get a channel ID");
-        return -1;
-    }
-    channels->next_id += 1;
-    return id;
-}
-
-static _PyChannelState *
-_channels_lookup(_channels *channels, int64_t id, PyThread_type_lock *pmutex)
-{
-    _PyChannelState *chan = NULL;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-    if (pmutex != NULL) {
-        *pmutex = NULL;
-    }
-
-    _channelref *ref = _channelref_find(channels->head, id, NULL);
-    if (ref == NULL) {
-        PyErr_Format(ChannelNotFoundError, "channel %" PRId64 " not found", id);
-        goto done;
-    }
-    if (ref->chan == NULL || !ref->chan->open) {
-        PyErr_Format(ChannelClosedError, "channel %" PRId64 " closed", id);
-        goto done;
-    }
-
-    if (pmutex != NULL) {
-        // The mutex will be closed by the caller.
-        *pmutex = channels->mutex;
-    }
-
-    chan = ref->chan;
-done:
-    if (pmutex == NULL || *pmutex == NULL) {
-        PyThread_release_lock(channels->mutex);
-    }
-    return chan;
-}
-
-static int64_t
-_channels_add(_channels *channels, _PyChannelState *chan)
-{
-    int64_t cid = -1;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-
-    // Create a new ref.
-    int64_t id = _channels_next_id(channels);
-    if (id < 0) {
-        goto done;
-    }
-    _channelref *ref = _channelref_new(id, chan);
-    if (ref == NULL) {
-        goto done;
-    }
-
-    // Add it to the list.
-    // We assume that the channel is a new one (not already in the list).
-    ref->next = channels->head;
-    channels->head = ref;
-    channels->numopen += 1;
-
-    cid = id;
-done:
-    PyThread_release_lock(channels->mutex);
-    return cid;
-}
-
-/* forward */
-static int _channel_set_closing(struct _channelref *, PyThread_type_lock);
-
-static int
-_channels_close(_channels *channels, int64_t cid, _PyChannelState **pchan,
-                int end, int force)
-{
-    int res = -1;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-    if (pchan != NULL) {
-        *pchan = NULL;
-    }
-
-    _channelref *ref = _channelref_find(channels->head, cid, NULL);
-    if (ref == NULL) {
-        PyErr_Format(ChannelNotFoundError, "channel %" PRId64 " not found", cid);
-        goto done;
-    }
-
-    if (ref->chan == NULL) {
-        PyErr_Format(ChannelClosedError, "channel %" PRId64 " closed", cid);
-        goto done;
-    }
-    else if (!force && end == CHANNEL_SEND && ref->chan->closing != NULL) {
-        PyErr_Format(ChannelClosedError, "channel %" PRId64 " closed", cid);
-        goto done;
-    }
-    else {
-        if (_channel_close_all(ref->chan, end, force) != 0) {
-            if (end == CHANNEL_SEND &&
-                    PyErr_ExceptionMatches(ChannelNotEmptyError)) {
-                if (ref->chan->closing != NULL) {
-                    PyErr_Format(ChannelClosedError,
-                                 "channel %" PRId64 " closed", cid);
-                    goto done;
-                }
-                // Mark the channel as closing and return.  The channel
-                // will be cleaned up in _channel_next().
-                PyErr_Clear();
-                if (_channel_set_closing(ref, channels->mutex) != 0) {
-                    goto done;
-                }
-                if (pchan != NULL) {
-                    *pchan = ref->chan;
-                }
-                res = 0;
-            }
-            goto done;
-        }
-        if (pchan != NULL) {
-            *pchan = ref->chan;
-        }
-        else  {
-            _channel_free(ref->chan);
-        }
-        ref->chan = NULL;
-    }
-
-    res = 0;
-done:
-    PyThread_release_lock(channels->mutex);
-    return res;
-}
-
-static void
-_channels_remove_ref(_channels *channels, _channelref *ref, _channelref *prev,
-                     _PyChannelState **pchan)
-{
-    if (ref == channels->head) {
-        channels->head = ref->next;
-    }
-    else {
-        prev->next = ref->next;
-    }
-    channels->numopen -= 1;
-
-    if (pchan != NULL) {
-        *pchan = ref->chan;
-    }
-    _channelref_free(ref);
-}
-
-static int
-_channels_remove(_channels *channels, int64_t id, _PyChannelState **pchan)
-{
-    int res = -1;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-
-    if (pchan != NULL) {
-        *pchan = NULL;
-    }
-
-    _channelref *prev = NULL;
-    _channelref *ref = _channelref_find(channels->head, id, &prev);
-    if (ref == NULL) {
-        PyErr_Format(ChannelNotFoundError, "channel %" PRId64 " not found", id);
-        goto done;
-    }
-
-    _channels_remove_ref(channels, ref, prev, pchan);
-
-    res = 0;
-done:
-    PyThread_release_lock(channels->mutex);
-    return res;
-}
-
-static int
-_channels_add_id_object(_channels *channels, int64_t id)
-{
-    int res = -1;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-
-    _channelref *ref = _channelref_find(channels->head, id, NULL);
-    if (ref == NULL) {
-        PyErr_Format(ChannelNotFoundError, "channel %" PRId64 " not found", id);
-        goto done;
-    }
-    ref->objcount += 1;
-
-    res = 0;
-done:
-    PyThread_release_lock(channels->mutex);
-    return res;
-}
-
-static void
-_channels_drop_id_object(_channels *channels, int64_t id)
-{
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-
-    _channelref *prev = NULL;
-    _channelref *ref = _channelref_find(channels->head, id, &prev);
-    if (ref == NULL) {
-        // Already destroyed.
-        goto done;
-    }
-    ref->objcount -= 1;
-
-    // Destroy if no longer used.
-    if (ref->objcount == 0) {
-        _PyChannelState *chan = NULL;
-        _channels_remove_ref(channels, ref, prev, &chan);
-        if (chan != NULL) {
-            _channel_free(chan);
-        }
-    }
-
-done:
-    PyThread_release_lock(channels->mutex);
-}
-
-static int64_t *
-_channels_list_all(_channels *channels, int64_t *count)
-{
-    int64_t *cids = NULL;
-    PyThread_acquire_lock(channels->mutex, WAIT_LOCK);
-    int64_t *ids = PyMem_NEW(int64_t, (Py_ssize_t)(channels->numopen));
-    if (ids == NULL) {
-        goto done;
-    }
-    _channelref *ref = channels->head;
-    for (int64_t i=0; ref != NULL; ref = ref->next, i++) {
-        ids[i] = ref->id;
-    }
-    *count = channels->numopen;
-
-    cids = ids;
-done:
-    PyThread_release_lock(channels->mutex);
-    return cids;
-}
-
-/* support for closing non-empty channels */
-
-struct _channel_closing {
-    struct _channelref *ref;
-};
-
-static int
-_channel_set_closing(struct _channelref *ref, PyThread_type_lock mutex) {
-    struct _channel *chan = ref->chan;
-    if (chan == NULL) {
-        // already closed
-        return 0;
-    }
-    int res = -1;
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-    if (chan->closing != NULL) {
-        PyErr_SetString(ChannelClosedError, "channel closed");
-        goto done;
-    }
-    chan->closing = PyMem_NEW(struct _channel_closing, 1);
-    if (chan->closing == NULL) {
-        goto done;
-    }
-    chan->closing->ref = ref;
-
-    res = 0;
-done:
-    PyThread_release_lock(chan->mutex);
-    return res;
-}
-
-static void
-_channel_clear_closing(struct _channel *chan) {
-    PyThread_acquire_lock(chan->mutex, WAIT_LOCK);
-    if (chan->closing != NULL) {
-        PyMem_Free(chan->closing);
-        chan->closing = NULL;
-    }
-    PyThread_release_lock(chan->mutex);
-}
-
-static void
-_channel_finish_closing(struct _channel *chan) {
-    struct _channel_closing *closing = chan->closing;
-    if (closing == NULL) {
-        return;
-    }
-    _channelref *ref = closing->ref;
-    _channel_clear_closing(chan);
-    // Do the things that would have been done in _channels_close().
-    ref->chan = NULL;
-    _channel_free(chan);
-}
-
-/* "high"-level channel-related functions */
-
-static int64_t
-_channel_create(_channels *channels)
-{
-    _PyChannelState *chan = _channel_new();
-    if (chan == NULL) {
-        return -1;
-    }
-    int64_t id = _channels_add(channels, chan);
-    if (id < 0) {
-        _channel_free(chan);
-        return -1;
-    }
-    return id;
-}
-
-static int
-_channel_destroy(_channels *channels, int64_t id)
-{
-    _PyChannelState *chan = NULL;
-    if (_channels_remove(channels, id, &chan) != 0) {
-        return -1;
-    }
-    if (chan != NULL) {
-        _channel_free(chan);
-    }
-    return 0;
-}
-
-static int
-_channel_send(_channels *channels, int64_t id, PyObject *obj)
-{
-    PyInterpreterState *interp = _get_current();
-    if (interp == NULL) {
-        return -1;
-    }
-
-    // Look up the channel.
-    PyThread_type_lock mutex = NULL;
-    _PyChannelState *chan = _channels_lookup(channels, id, &mutex);
-    if (chan == NULL) {
-        return -1;
-    }
-    // Past this point we are responsible for releasing the mutex.
-
-    if (chan->closing != NULL) {
-        PyErr_Format(ChannelClosedError, "channel %" PRId64 " closed", id);
-        PyThread_release_lock(mutex);
-        return -1;
-    }
-
-    // Convert the object to cross-interpreter data.
-    _PyCrossInterpreterData *data = PyMem_NEW(_PyCrossInterpreterData, 1);
-    if (data == NULL) {
-        PyThread_release_lock(mutex);
-        return -1;
-    }
-    if (_PyObject_GetCrossInterpreterData(obj, data) != 0) {
-        PyThread_release_lock(mutex);
-        PyMem_Free(data);
-        return -1;
-    }
-
-    // Add the data to the channel.
-    int res = _channel_add(chan, PyInterpreterState_GetID(interp), data);
-    PyThread_release_lock(mutex);
-    if (res != 0) {
-        _PyCrossInterpreterData_Release(data);
-        PyMem_Free(data);
-        return -1;
-    }
-
-    return 0;
-}
-
-static PyObject *
-_channel_recv(_channels *channels, int64_t id)
-{
-    PyInterpreterState *interp = _get_current();
-    if (interp == NULL) {
-        return NULL;
-    }
-
-    // Look up the channel.
-    PyThread_type_lock mutex = NULL;
-    _PyChannelState *chan = _channels_lookup(channels, id, &mutex);
-    if (chan == NULL) {
-        return NULL;
-    }
-    // Past this point we are responsible for releasing the mutex.
-
-    // Pop off the next item from the channel.
-    _PyCrossInterpreterData *data = _channel_next(chan, PyInterpreterState_GetID(interp));
-    PyThread_release_lock(mutex);
-    if (data == NULL) {
-        return NULL;
-    }
-
-    // Convert the data back to an object.
-    PyObject *obj = _PyCrossInterpreterData_NewObject(data);
-    _PyCrossInterpreterData_Release(data);
-    PyMem_Free(data);
-    if (obj == NULL) {
-        return NULL;
-    }
-
-    return obj;
-}
-
-static int
-_channel_drop(_channels *channels, int64_t id, int send, int recv)
-{
-    PyInterpreterState *interp = _get_current();
-    if (interp == NULL) {
-        return -1;
-    }
-
-    // Look up the channel.
-    PyThread_type_lock mutex = NULL;
-    _PyChannelState *chan = _channels_lookup(channels, id, &mutex);
-    if (chan == NULL) {
-        return -1;
-    }
-    // Past this point we are responsible for releasing the mutex.
-
-    // Close one or both of the two ends.
-    int res = _channel_close_interpreter(chan, PyInterpreterState_GetID(interp), send-recv);
-    PyThread_release_lock(mutex);
-    return res;
-}
-
-static int
-_channel_close(_channels *channels, int64_t id, int end, int force)
-{
-    return _channels_close(channels, id, NULL, end, force);
-}
-
-static int
-_channel_is_associated(_channels *channels, int64_t cid, int64_t interp,
-                       int send)
-{
-    _PyChannelState *chan = _channels_lookup(channels, cid, NULL);
-    if (chan == NULL) {
-        return -1;
-    } else if (send && chan->closing != NULL) {
-        PyErr_Format(ChannelClosedError, "channel %" PRId64 " closed", cid);
-        return -1;
-    }
-
-    _channelend *end = _channelend_find(send ? chan->ends->send : chan->ends->recv,
-                                        interp, NULL);
-
-    return (end != NULL && end->open);
-}
-
-/* ChannelID class */
-
-static PyTypeObject ChannelIDtype;
-
-typedef struct channelid {
-    PyObject_HEAD
-    int64_t id;
-    int end;
-    int resolve;
-    _channels *channels;
-} channelid;
-
-static int
-channel_id_converter(PyObject *arg, void *ptr)
-{
-    int64_t cid;
-    if (PyObject_TypeCheck(arg, &ChannelIDtype)) {
-        cid = ((channelid *)arg)->id;
-    }
-    else if (PyIndex_Check(arg)) {
-        cid = PyLong_AsLongLong(arg);
-        if (cid == -1 && PyErr_Occurred()) {
-            return 0;
-        }
-        if (cid < 0) {
-            PyErr_Format(PyExc_ValueError,
-                        "channel ID must be a non-negative int, got %R", arg);
-            return 0;
-        }
-    }
-    else {
-        PyErr_Format(PyExc_TypeError,
-                     "channel ID must be an int, got %.100s",
-                     Py_TYPE(arg)->tp_name);
-        return 0;
-    }
-    *(int64_t *)ptr = cid;
-    return 1;
-}
-
-static channelid *
-newchannelid(PyTypeObject *cls, int64_t cid, int end, _channels *channels,
-             int force, int resolve)
-{
-    channelid *self = PyObject_New(channelid, cls);
-    if (self == NULL) {
-        return NULL;
-    }
-    self->id = cid;
-    self->end = end;
-    self->resolve = resolve;
-    self->channels = channels;
-
-    if (_channels_add_id_object(channels, cid) != 0) {
-        if (force && PyErr_ExceptionMatches(ChannelNotFoundError)) {
-            PyErr_Clear();
-        }
-        else {
-            Py_DECREF((PyObject *)self);
-            return NULL;
-        }
-    }
-
-    return self;
-}
-
-static _channels * _global_channels(void);
-
-static PyObject *
-channelid_new(PyTypeObject *cls, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"id", "send", "recv", "force", "_resolve", NULL};
-    int64_t cid;
-    int send = -1;
-    int recv = -1;
-    int force = 0;
-    int resolve = 0;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds,
-                                     "O&|$pppp:ChannelID.__new__", kwlist,
-                                     channel_id_converter, &cid, &send, &recv, &force, &resolve))
-        return NULL;
-
-    // Handle "send" and "recv".
-    if (send == 0 && recv == 0) {
-        PyErr_SetString(PyExc_ValueError,
-                        "'send' and 'recv' cannot both be False");
-        return NULL;
-    }
-
-    int end = 0;
-    if (send == 1) {
-        if (recv == 0 || recv == -1) {
-            end = CHANNEL_SEND;
-        }
-    }
-    else if (recv == 1) {
-        end = CHANNEL_RECV;
-    }
-
-    return (PyObject *)newchannelid(cls, cid, end, _global_channels(),
-                                    force, resolve);
-}
-
-static void
-channelid_dealloc(PyObject *v)
-{
-    int64_t cid = ((channelid *)v)->id;
-    _channels *channels = ((channelid *)v)->channels;
-    Py_TYPE(v)->tp_free(v);
-
-    _channels_drop_id_object(channels, cid);
-}
-
-static PyObject *
-channelid_repr(PyObject *self)
-{
-    PyTypeObject *type = Py_TYPE(self);
-    const char *name = _PyType_Name(type);
-
-    channelid *cid = (channelid *)self;
-    const char *fmt;
-    if (cid->end == CHANNEL_SEND) {
-        fmt = "%s(%" PRId64 ", send=True)";
-    }
-    else if (cid->end == CHANNEL_RECV) {
-        fmt = "%s(%" PRId64 ", recv=True)";
-    }
-    else {
-        fmt = "%s(%" PRId64 ")";
-    }
-    return PyUnicode_FromFormat(fmt, name, cid->id);
-}
-
-static PyObject *
-channelid_str(PyObject *self)
-{
-    channelid *cid = (channelid *)self;
-    return PyUnicode_FromFormat("%" PRId64 "", cid->id);
-}
-
-static PyObject *
-channelid_int(PyObject *self)
-{
-    channelid *cid = (channelid *)self;
-    return PyLong_FromLongLong(cid->id);
-}
-
-static PyNumberMethods channelid_as_number = {
-     0,                        /* nb_add */
-     0,                        /* nb_subtract */
-     0,                        /* nb_multiply */
-     0,                        /* nb_remainder */
-     0,                        /* nb_divmod */
-     0,                        /* nb_power */
-     0,                        /* nb_negative */
-     0,                        /* nb_positive */
-     0,                        /* nb_absolute */
-     0,                        /* nb_bool */
-     0,                        /* nb_invert */
-     0,                        /* nb_lshift */
-     0,                        /* nb_rshift */
-     0,                        /* nb_and */
-     0,                        /* nb_xor */
-     0,                        /* nb_or */
-     (unaryfunc)channelid_int, /* nb_int */
-     0,                        /* nb_reserved */
-     0,                        /* nb_float */
-
-     0,                        /* nb_inplace_add */
-     0,                        /* nb_inplace_subtract */
-     0,                        /* nb_inplace_multiply */
-     0,                        /* nb_inplace_remainder */
-     0,                        /* nb_inplace_power */
-     0,                        /* nb_inplace_lshift */
-     0,                        /* nb_inplace_rshift */
-     0,                        /* nb_inplace_and */
-     0,                        /* nb_inplace_xor */
-     0,                        /* nb_inplace_or */
-
-     0,                        /* nb_floor_divide */
-     0,                        /* nb_true_divide */
-     0,                        /* nb_inplace_floor_divide */
-     0,                        /* nb_inplace_true_divide */
-
-     (unaryfunc)channelid_int, /* nb_index */
-};
-
-static Py_hash_t
-channelid_hash(PyObject *self)
-{
-    channelid *cid = (channelid *)self;
-    PyObject *id = PyLong_FromLongLong(cid->id);
-    if (id == NULL) {
-        return -1;
-    }
-    Py_hash_t hash = PyObject_Hash(id);
-    Py_DECREF(id);
-    return hash;
-}
-
-static PyObject *
-channelid_richcompare(PyObject *self, PyObject *other, int op)
-{
-    if (op != Py_EQ && op != Py_NE) {
-        Py_RETURN_NOTIMPLEMENTED;
-    }
-
-    if (!PyObject_TypeCheck(self, &ChannelIDtype)) {
-        Py_RETURN_NOTIMPLEMENTED;
-    }
-
-    channelid *cid = (channelid *)self;
-    int equal;
-    if (PyObject_TypeCheck(other, &ChannelIDtype)) {
-        channelid *othercid = (channelid *)other;
-        equal = (cid->end == othercid->end) && (cid->id == othercid->id);
-    }
-    else if (PyLong_Check(other)) {
-        /* Fast path */
-        int overflow;
-        long long othercid = PyLong_AsLongLongAndOverflow(other, &overflow);
-        if (othercid == -1 && PyErr_Occurred()) {
-            return NULL;
-        }
-        equal = !overflow && (othercid >= 0) && (cid->id == othercid);
-    }
-    else if (PyNumber_Check(other)) {
-        PyObject *pyid = PyLong_FromLongLong(cid->id);
-        if (pyid == NULL) {
-            return NULL;
-        }
-        PyObject *res = PyObject_RichCompare(pyid, other, op);
-        Py_DECREF(pyid);
-        return res;
-    }
-    else {
-        Py_RETURN_NOTIMPLEMENTED;
-    }
-
-    if ((op == Py_EQ && equal) || (op == Py_NE && !equal)) {
-        Py_RETURN_TRUE;
-    }
-    Py_RETURN_FALSE;
-}
-
-static PyObject *
-_channel_from_cid(PyObject *cid, int end)
-{
-    PyObject *highlevel = PyImport_ImportModule("interpreters");
-    if (highlevel == NULL) {
-        PyErr_Clear();
-        highlevel = PyImport_ImportModule("test.support.interpreters");
-        if (highlevel == NULL) {
-            return NULL;
-        }
-    }
-    const char *clsname = (end == CHANNEL_RECV) ? "RecvChannel" :
-                                                  "SendChannel";
-    PyObject *cls = PyObject_GetAttrString(highlevel, clsname);
-    Py_DECREF(highlevel);
-    if (cls == NULL) {
-        return NULL;
-    }
-    PyObject *chan = PyObject_CallFunctionObjArgs(cls, cid, NULL);
-    Py_DECREF(cls);
-    if (chan == NULL) {
-        return NULL;
-    }
-    return chan;
-}
-
-struct _channelid_xid {
-    int64_t id;
-    int end;
-    int resolve;
-};
-
-static PyObject *
-_channelid_from_xid(_PyCrossInterpreterData *data)
-{
-    struct _channelid_xid *xid = (struct _channelid_xid *)data->data;
-    // Note that we do not preserve the "resolve" flag.
-    PyObject *cid = (PyObject *)newchannelid(&ChannelIDtype, xid->id, xid->end,
-                                             _global_channels(), 0, 0);
-    if (xid->end == 0) {
-        return cid;
-    }
-    if (!xid->resolve) {
-        return cid;
-    }
-
-    /* Try returning a high-level channel end but fall back to the ID. */
-    PyObject *chan = _channel_from_cid(cid, xid->end);
-    if (chan == NULL) {
-        PyErr_Clear();
-        return cid;
-    }
-    Py_DECREF(cid);
-    return chan;
-}
+/* interpreter-specific code ************************************************/
 
 static int
-_channelid_shared(PyObject *obj, _PyCrossInterpreterData *data)
+exceptions_init(PyObject *mod)
 {
-    struct _channelid_xid *xid = PyMem_NEW(struct _channelid_xid, 1);
-    if (xid == NULL) {
+    module_state *state = get_module_state(mod);
+    if (state == NULL) {
         return -1;
     }
-    xid->id = ((channelid *)obj)->id;
-    xid->end = ((channelid *)obj)->end;
-    xid->resolve = ((channelid *)obj)->resolve;
 
-    data->data = xid;
-    Py_INCREF(obj);
-    data->obj = obj;
-    data->new_object = _channelid_from_xid;
-    data->free = PyMem_Free;
-    return 0;
-}
+#define ADD(NAME, BASE) \
+    do { \
+        assert(state->NAME == NULL); \
+        state->NAME = ADD_NEW_EXCEPTION(mod, NAME, BASE); \
+        if (state->NAME == NULL) { \
+            return -1; \
+        } \
+    } while (0)
 
-static PyObject *
-channelid_end(PyObject *self, void *end)
-{
-    int force = 1;
-    channelid *cid = (channelid *)self;
-    if (end != NULL) {
-        return (PyObject *)newchannelid(Py_TYPE(self), cid->id, *(int *)end,
-                                        cid->channels, force, cid->resolve);
-    }
-
-    if (cid->end == CHANNEL_SEND) {
-        return PyUnicode_InternFromString("send");
-    }
-    if (cid->end == CHANNEL_RECV) {
-        return PyUnicode_InternFromString("recv");
-    }
-    return PyUnicode_InternFromString("both");
-}
-
-static int _channelid_end_send = CHANNEL_SEND;
-static int _channelid_end_recv = CHANNEL_RECV;
-
-static PyGetSetDef channelid_getsets[] = {
-    {"end", (getter)channelid_end, NULL,
-     PyDoc_STR("'send', 'recv', or 'both'")},
-    {"send", (getter)channelid_end, NULL,
-     PyDoc_STR("the 'send' end of the channel"), &_channelid_end_send},
-    {"recv", (getter)channelid_end, NULL,
-     PyDoc_STR("the 'recv' end of the channel"), &_channelid_end_recv},
-    {NULL}
-};
-
-PyDoc_STRVAR(channelid_doc,
-"A channel ID identifies a channel and may be used as an int.");
-
-static PyTypeObject ChannelIDtype = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
-    "_xxsubinterpreters.ChannelID", /* tp_name */
-    sizeof(channelid),              /* tp_basicsize */
-    0,                              /* tp_itemsize */
-    (destructor)channelid_dealloc,  /* tp_dealloc */
-    0,                              /* tp_vectorcall_offset */
-    0,                              /* tp_getattr */
-    0,                              /* tp_setattr */
-    0,                              /* tp_as_async */
-    (reprfunc)channelid_repr,       /* tp_repr */
-    &channelid_as_number,           /* tp_as_number */
-    0,                              /* tp_as_sequence */
-    0,                              /* tp_as_mapping */
-    channelid_hash,                 /* tp_hash */
-    0,                              /* tp_call */
-    (reprfunc)channelid_str,        /* tp_str */
-    0,                              /* tp_getattro */
-    0,                              /* tp_setattro */
-    0,                              /* tp_as_buffer */
-    // Use Py_TPFLAGS_DISALLOW_INSTANTIATION so the type cannot be instantiated
-    // from Python code.  We do this because there is a strong relationship
-    // between channel IDs and the channel lifecycle, so this limitation avoids
-    // related complications. Use the _channel_id() function instead.
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE
-        | Py_TPFLAGS_DISALLOW_INSTANTIATION, /* tp_flags */
-    channelid_doc,                  /* tp_doc */
-    0,                              /* tp_traverse */
-    0,                              /* tp_clear */
-    channelid_richcompare,          /* tp_richcompare */
-    0,                              /* tp_weaklistoffset */
-    0,                              /* tp_iter */
-    0,                              /* tp_iternext */
-    0,                              /* tp_methods */
-    0,                              /* tp_members */
-    channelid_getsets,              /* tp_getset */
-};
-
-
-/* interpreter-specific code ************************************************/
-
-static PyObject * RunFailedError = NULL;
-
-static int
-interp_exceptions_init(PyObject *ns)
-{
-    // XXX Move the exceptions into per-module memory?
-
-    if (RunFailedError == NULL) {
-        // An uncaught exception came out of interp_run_string().
-        RunFailedError = PyErr_NewException("_xxsubinterpreters.RunFailedError",
-                                            PyExc_RuntimeError, NULL);
-        if (RunFailedError == NULL) {
-            return -1;
-        }
-        if (PyDict_SetItemString(ns, "RunFailedError", RunFailedError) != 0) {
-            return -1;
-        }
-    }
+    // An uncaught exception came out of interp_run_string().
+    ADD(RunFailedError, PyExc_RuntimeError);
+#undef ADD
 
     return 0;
 }
 
 static int
-_is_running(PyInterpreterState *interp)
-{
-    PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
-    if (PyThreadState_Next(tstate) != NULL) {
-        PyErr_SetString(PyExc_RuntimeError,
-                        "interpreter has more than one thread");
-        return -1;
-    }
-
-    assert(!PyErr_Occurred());
-    _PyInterpreterFrame *frame = tstate->cframe->current_frame;
-    if (frame == NULL) {
-        return 0;
-    }
-    return 1;
-}
-
-static int
-_ensure_not_running(PyInterpreterState *interp)
+_run_script(PyInterpreterState *interp, const char *codestr,
+            _sharedns *shared, _sharedexception *sharedexc)
 {
-    int is_running = _is_running(interp);
-    if (is_running < 0) {
-        return -1;
-    }
-    if (is_running) {
-        PyErr_Format(PyExc_RuntimeError, "interpreter already running");
+    if (_PyInterpreterState_SetRunningMain(interp) < 0) {
+        // We skip going through the shared exception.
         return -1;
     }
-    return 0;
-}
 
-static int
-_run_script(PyInterpreterState *interp, const char *codestr,
-            _sharedns *shared, _sharedexception **exc)
-{
-    PyObject *exctype = NULL;
     PyObject *excval = NULL;
-    PyObject *tb = NULL;
-
     PyObject *main_mod = _PyInterpreterState_GetMainModule(interp);
     if (main_mod == NULL) {
         goto error;
@@ -1895,36 +397,31 @@ _run_script(PyInterpreterState *interp, const char *codestr,
     else {
         Py_DECREF(result);  // We throw away the result.
     }
+    _PyInterpreterState_SetNotRunningMain(interp);
 
-    *exc = NULL;
+    *sharedexc = no_exception;
     return 0;
 
 error:
-    PyErr_Fetch(&exctype, &excval, &tb);
-
-    _sharedexception *sharedexc = _sharedexception_bind(exctype, excval, tb);
-    Py_XDECREF(exctype);
-    Py_XDECREF(excval);
-    Py_XDECREF(tb);
-    if (sharedexc == NULL) {
-        fprintf(stderr, "RunFailedError: script raised an uncaught exception");
+    excval = PyErr_GetRaisedException();
+    const char *failure = _sharedexception_bind(excval, sharedexc);
+    if (failure != NULL) {
+        fprintf(stderr,
+                "RunFailedError: script raised an uncaught exception (%s)",
+                failure);
         PyErr_Clear();
-        sharedexc = NULL;
     }
-    else {
-        assert(!PyErr_Occurred());
-    }
-    *exc = sharedexc;
+    Py_XDECREF(excval);
+    assert(!PyErr_Occurred());
+    _PyInterpreterState_SetNotRunningMain(interp);
     return -1;
 }
 
 static int
-_run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
-                           PyObject *shareables)
+_run_script_in_interpreter(PyObject *mod, PyInterpreterState *interp,
+                           const char *codestr, PyObject *shareables)
 {
-    if (_ensure_not_running(interp) < 0) {
-        return -1;
-    }
+    module_state *state = get_module_state(mod);
 
     _sharedns *shared = _get_shared_ns(shareables);
     if (shared == NULL && PyErr_Occurred()) {
@@ -1934,14 +431,32 @@ _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
     // Switch to interpreter.
     PyThreadState *save_tstate = NULL;
     if (interp != PyInterpreterState_Get()) {
-        // XXX Using the "head" thread isn't strictly correct.
+        // XXX gh-109860: Using the "head" thread isn't strictly correct.
         PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
+        assert(tstate != NULL);
+        // Hack (until gh-109860): The interpreter's initial thread state
+        // is least likely to break.
+        while(tstate->next != NULL) {
+            tstate = tstate->next;
+        }
+        // We must do this check before switching interpreters, so any
+        // exception gets raised in the right one.
+        // XXX gh-109860: Drop this redundant check once we stop
+        // re-using tstates that might already be in use.
+        if (_PyInterpreterState_IsRunningMain(interp)) {
+            PyErr_SetString(PyExc_RuntimeError,
+                            "interpreter already running");
+            if (shared != NULL) {
+                _sharedns_free(shared);
+            }
+            return -1;
+        }
         // XXX Possible GILState issues?
         save_tstate = PyThreadState_Swap(tstate);
     }
 
     // Run the script.
-    _sharedexception *exc = NULL;
+    _sharedexception exc = {NULL, NULL};
     int result = _run_script(interp, codestr, shared, &exc);
 
     // Switch back.
@@ -1950,13 +465,15 @@ _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
     }
 
     // Propagate any exception out to the caller.
-    if (exc != NULL) {
-        _sharedexception_apply(exc, RunFailedError);
-        _sharedexception_free(exc);
+    if (exc.name != NULL) {
+        assert(state != NULL);
+        _sharedexception_apply(&exc, state->RunFailedError);
     }
     else if (result != 0) {
-        // We were unable to allocate a shared exception.
-        PyErr_NoMemory();
+        if (!PyErr_Occurred()) {
+            // We were unable to allocate a shared exception.
+            PyErr_NoMemory();
+        }
     }
 
     if (shared != NULL) {
@@ -1969,27 +486,6 @@ _run_script_in_interpreter(PyInterpreterState *interp, const char *codestr,
 
 /* module level code ********************************************************/
 
-/* globals is the process-global state for the module.  It holds all
-   the data that we need to share between interpreters, so it cannot
-   hold PyObject values. */
-static struct globals {
-    _channels channels;
-} _globals = {{0}};
-
-static int
-_init_globals(void)
-{
-    if (_channels_init(&_globals.channels) != 0) {
-        return -1;
-    }
-    return 0;
-}
-
-static _channels *
-_global_channels(void) {
-    return &_globals.channels;
-}
-
 static PyObject *
 interp_create(PyObject *self, PyObject *args, PyObject *kwds)
 {
@@ -2002,17 +498,26 @@ interp_create(PyObject *self, PyObject *args, PyObject *kwds)
     }
 
     // Create and initialize the new interpreter.
-    PyThreadState *save_tstate = _PyThreadState_GET();
+    PyThreadState *save_tstate = PyThreadState_Get();
+    assert(save_tstate != NULL);
+    const PyInterpreterConfig config = isolated
+        ? (PyInterpreterConfig)_PyInterpreterConfig_INIT
+        : (PyInterpreterConfig)_PyInterpreterConfig_LEGACY_INIT;
     // XXX Possible GILState issues?
-    PyThreadState *tstate = _Py_NewInterpreter(isolated);
+    PyThreadState *tstate = NULL;
+    PyStatus status = Py_NewInterpreterFromConfig(&tstate, &config);
     PyThreadState_Swap(save_tstate);
-    if (tstate == NULL) {
+    if (PyStatus_Exception(status)) {
         /* Since no new thread state was created, there is no exception to
            propagate; raise a fresh one after swapping in the old thread
            state. */
+        _PyErr_SetFromPyStatus(status);
+        PyObject *exc = PyErr_GetRaisedException();
         PyErr_SetString(PyExc_RuntimeError, "interpreter creation failed");
+        _PyErr_ChainExceptions1(exc);
         return NULL;
     }
+    assert(tstate != NULL);
     PyInterpreterState *interp = PyThreadState_GetInterpreter(tstate);
     PyObject *idobj = _PyInterpreterState_GetIDObject(interp);
     if (idobj == NULL) {
@@ -2050,7 +555,7 @@ interp_destroy(PyObject *self, PyObject *args, PyObject *kwds)
     }
 
     // Ensure we don't try to destroy the current interpreter.
-    PyInterpreterState *current = _get_current();
+    PyInterpreterState *current = _get_current_interp();
     if (current == NULL) {
         return NULL;
     }
@@ -2063,12 +568,20 @@ interp_destroy(PyObject *self, PyObject *args, PyObject *kwds)
     // Ensure the interpreter isn't running.
     /* XXX We *could* support destroying a running interpreter but
        aren't going to worry about it for now. */
-    if (_ensure_not_running(interp) < 0) {
+    if (_PyInterpreterState_IsRunningMain(interp)) {
+        PyErr_Format(PyExc_RuntimeError, "interpreter running");
         return NULL;
     }
 
     // Destroy the interpreter.
+    // XXX gh-109860: Using the "head" thread isn't strictly correct.
     PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
+    assert(tstate != NULL);
+    // Hack (until gh-109860): The interpreter's initial thread state
+    // is least likely to break.
+    while(tstate->next != NULL) {
+        tstate = tstate->next;
+    }
     // XXX Possible GILState issues?
     PyThreadState *save_tstate = PyThreadState_Swap(tstate);
     Py_EndInterpreter(tstate);
@@ -2127,7 +640,7 @@ Return a list containing the ID of every existing interpreter.");
 static PyObject *
 interp_get_current(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
-    PyInterpreterState *interp =_get_current();
+    PyInterpreterState *interp =_get_current_interp();
     if (interp == NULL) {
         return NULL;
     }
@@ -2185,7 +698,7 @@ interp_run_string(PyObject *self, PyObject *args, PyObject *kwds)
     }
 
     // Run the code in the interpreter.
-    if (_run_script_in_interpreter(interp, codestr, shared) != 0) {
+    if (_run_script_in_interpreter(self, interp, codestr, shared) != 0) {
         return NULL;
     }
     Py_RETURN_NONE;
@@ -2237,11 +750,7 @@ interp_is_running(PyObject *self, PyObject *args, PyObject *kwds)
     if (interp == NULL) {
         return NULL;
     }
-    int is_running = _is_running(interp);
-    if (is_running < 0) {
-        return NULL;
-    }
-    if (is_running) {
+    if (_PyInterpreterState_IsRunningMain(interp)) {
         Py_RETURN_TRUE;
     }
     Py_RETURN_FALSE;
@@ -2252,295 +761,6 @@ PyDoc_STRVAR(is_running_doc,
 \n\
 Return whether or not the identified interpreter is running.");
 
-static PyObject *
-channel_create(PyObject *self, PyObject *Py_UNUSED(ignored))
-{
-    int64_t cid = _channel_create(&_globals.channels);
-    if (cid < 0) {
-        return NULL;
-    }
-    PyObject *id = (PyObject *)newchannelid(&ChannelIDtype, cid, 0,
-                                            &_globals.channels, 0, 0);
-    if (id == NULL) {
-        if (_channel_destroy(&_globals.channels, cid) != 0) {
-            // XXX issue a warning?
-        }
-        return NULL;
-    }
-    assert(((channelid *)id)->channels != NULL);
-    return id;
-}
-
-PyDoc_STRVAR(channel_create_doc,
-"channel_create() -> cid\n\
-\n\
-Create a new cross-interpreter channel and return a unique generated ID.");
-
-static PyObject *
-channel_destroy(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"cid", NULL};
-    int64_t cid;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O&:channel_destroy", kwlist,
-                                     channel_id_converter, &cid)) {
-        return NULL;
-    }
-
-    if (_channel_destroy(&_globals.channels, cid) != 0) {
-        return NULL;
-    }
-    Py_RETURN_NONE;
-}
-
-PyDoc_STRVAR(channel_destroy_doc,
-"channel_destroy(cid)\n\
-\n\
-Close and finalize the channel.  Afterward attempts to use the channel\n\
-will behave as though it never existed.");
-
-static PyObject *
-channel_list_all(PyObject *self, PyObject *Py_UNUSED(ignored))
-{
-    int64_t count = 0;
-    int64_t *cids = _channels_list_all(&_globals.channels, &count);
-    if (cids == NULL) {
-        if (count == 0) {
-            return PyList_New(0);
-        }
-        return NULL;
-    }
-    PyObject *ids = PyList_New((Py_ssize_t)count);
-    if (ids == NULL) {
-        goto finally;
-    }
-    int64_t *cur = cids;
-    for (int64_t i=0; i < count; cur++, i++) {
-        PyObject *id = (PyObject *)newchannelid(&ChannelIDtype, *cur, 0,
-                                                &_globals.channels, 0, 0);
-        if (id == NULL) {
-            Py_DECREF(ids);
-            ids = NULL;
-            break;
-        }
-        PyList_SET_ITEM(ids, i, id);
-    }
-
-finally:
-    PyMem_Free(cids);
-    return ids;
-}
-
-PyDoc_STRVAR(channel_list_all_doc,
-"channel_list_all() -> [cid]\n\
-\n\
-Return the list of all IDs for active channels.");
-
-static PyObject *
-channel_list_interpreters(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"cid", "send", NULL};
-    int64_t cid;            /* Channel ID */
-    int send = 0;           /* Send or receive end? */
-    int64_t id;
-    PyObject *ids, *id_obj;
-    PyInterpreterState *interp;
-
-    if (!PyArg_ParseTupleAndKeywords(
-            args, kwds, "O&$p:channel_list_interpreters",
-            kwlist, channel_id_converter, &cid, &send)) {
-        return NULL;
-    }
-
-    ids = PyList_New(0);
-    if (ids == NULL) {
-        goto except;
-    }
-
-    interp = PyInterpreterState_Head();
-    while (interp != NULL) {
-        id = PyInterpreterState_GetID(interp);
-        assert(id >= 0);
-        int res = _channel_is_associated(&_globals.channels, cid, id, send);
-        if (res < 0) {
-            goto except;
-        }
-        if (res) {
-            id_obj = _PyInterpreterState_GetIDObject(interp);
-            if (id_obj == NULL) {
-                goto except;
-            }
-            res = PyList_Insert(ids, 0, id_obj);
-            Py_DECREF(id_obj);
-            if (res < 0) {
-                goto except;
-            }
-        }
-        interp = PyInterpreterState_Next(interp);
-    }
-
-    goto finally;
-
-except:
-    Py_XDECREF(ids);
-    ids = NULL;
-
-finally:
-    return ids;
-}
-
-PyDoc_STRVAR(channel_list_interpreters_doc,
-"channel_list_interpreters(cid, *, send) -> [id]\n\
-\n\
-Return the list of all interpreter IDs associated with an end of the channel.\n\
-\n\
-The 'send' argument should be a boolean indicating whether to use the send or\n\
-receive end.");
-
-
-static PyObject *
-channel_send(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"cid", "obj", NULL};
-    int64_t cid;
-    PyObject *obj;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O&O:channel_send", kwlist,
-                                     channel_id_converter, &cid, &obj)) {
-        return NULL;
-    }
-
-    if (_channel_send(&_globals.channels, cid, obj) != 0) {
-        return NULL;
-    }
-    Py_RETURN_NONE;
-}
-
-PyDoc_STRVAR(channel_send_doc,
-"channel_send(cid, obj)\n\
-\n\
-Add the object's data to the channel's queue.");
-
-static PyObject *
-channel_recv(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"cid", "default", NULL};
-    int64_t cid;
-    PyObject *dflt = NULL;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O&|O:channel_recv", kwlist,
-                                     channel_id_converter, &cid, &dflt)) {
-        return NULL;
-    }
-    Py_XINCREF(dflt);
-
-    PyObject *obj = _channel_recv(&_globals.channels, cid);
-    if (obj != NULL) {
-        Py_XDECREF(dflt);
-        return obj;
-    } else if (PyErr_Occurred()) {
-        Py_XDECREF(dflt);
-        return NULL;
-    } else if (dflt != NULL) {
-        return dflt;
-    } else {
-        PyErr_Format(ChannelEmptyError, "channel %" PRId64 " is empty", cid);
-        return NULL;
-    }
-}
-
-PyDoc_STRVAR(channel_recv_doc,
-"channel_recv(cid, [default]) -> obj\n\
-\n\
-Return a new object from the data at the front of the channel's queue.\n\
-\n\
-If there is nothing to receive then raise ChannelEmptyError, unless\n\
-a default value is provided.  In that case return it.");
-
-static PyObject *
-channel_close(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    static char *kwlist[] = {"cid", "send", "recv", "force", NULL};
-    int64_t cid;
-    int send = 0;
-    int recv = 0;
-    int force = 0;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds,
-                                     "O&|$ppp:channel_close", kwlist,
-                                     channel_id_converter, &cid, &send, &recv, &force)) {
-        return NULL;
-    }
-
-    if (_channel_close(&_globals.channels, cid, send-recv, force) != 0) {
-        return NULL;
-    }
-    Py_RETURN_NONE;
-}
-
-PyDoc_STRVAR(channel_close_doc,
-"channel_close(cid, *, send=None, recv=None, force=False)\n\
-\n\
-Close the channel for all interpreters.\n\
-\n\
-If the channel is empty then the keyword args are ignored and both\n\
-ends are immediately closed.  Otherwise, if 'force' is True then\n\
-all queued items are released and both ends are immediately\n\
-closed.\n\
-\n\
-If the channel is not empty *and* 'force' is False then following\n\
-happens:\n\
-\n\
- * recv is True (regardless of send):\n\
-   - raise ChannelNotEmptyError\n\
- * recv is None and send is None:\n\
-   - raise ChannelNotEmptyError\n\
- * send is True and recv is not True:\n\
-   - fully close the 'send' end\n\
-   - close the 'recv' end to interpreters not already receiving\n\
-   - fully close it once empty\n\
-\n\
-Closing an already closed channel results in a ChannelClosedError.\n\
-\n\
-Once the channel's ID has no more ref counts in any interpreter\n\
-the channel will be destroyed.");
-
-static PyObject *
-channel_release(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    // Note that only the current interpreter is affected.
-    static char *kwlist[] = {"cid", "send", "recv", "force", NULL};
-    int64_t cid;
-    int send = 0;
-    int recv = 0;
-    int force = 0;
-    if (!PyArg_ParseTupleAndKeywords(args, kwds,
-                                     "O&|$ppp:channel_release", kwlist,
-                                     channel_id_converter, &cid, &send, &recv, &force)) {
-        return NULL;
-    }
-    if (send == 0 && recv == 0) {
-        send = 1;
-        recv = 1;
-    }
-
-    // XXX Handle force is True.
-    // XXX Fix implicit release.
-
-    if (_channel_drop(&_globals.channels, cid, send, recv) != 0) {
-        return NULL;
-    }
-    Py_RETURN_NONE;
-}
-
-PyDoc_STRVAR(channel_release_doc,
-"channel_release(cid, *, send=None, recv=None, force=True)\n\
-\n\
-Close the channel for the current interpreter.  'send' and 'recv'\n\
-(bool) may be used to indicate the ends to close.  By default both\n\
-ends are closed.  Closing an already closed end is a noop.");
-
-static PyObject *
-channel__channel_id(PyObject *self, PyObject *args, PyObject *kwds)
-{
-    return channelid_new(&ChannelIDtype, args, kwds);
-}
 
 static PyMethodDef module_functions[] = {
     {"create",                    _PyCFunction_CAST(interp_create),
@@ -2553,6 +773,7 @@ static PyMethodDef module_functions[] = {
      METH_NOARGS, get_current_doc},
     {"get_main",                  interp_get_main,
      METH_NOARGS, get_main_doc},
+
     {"is_running",                _PyCFunction_CAST(interp_is_running),
      METH_VARARGS | METH_KEYWORDS, is_running_doc},
     {"run_string",                _PyCFunction_CAST(interp_run_string),
@@ -2561,25 +782,6 @@ static PyMethodDef module_functions[] = {
     {"is_shareable",              _PyCFunction_CAST(object_is_shareable),
      METH_VARARGS | METH_KEYWORDS, is_shareable_doc},
 
-    {"channel_create",            channel_create,
-     METH_NOARGS, channel_create_doc},
-    {"channel_destroy",           _PyCFunction_CAST(channel_destroy),
-     METH_VARARGS | METH_KEYWORDS, channel_destroy_doc},
-    {"channel_list_all",          channel_list_all,
-     METH_NOARGS, channel_list_all_doc},
-    {"channel_list_interpreters", _PyCFunction_CAST(channel_list_interpreters),
-     METH_VARARGS | METH_KEYWORDS, channel_list_interpreters_doc},
-    {"channel_send",              _PyCFunction_CAST(channel_send),
-     METH_VARARGS | METH_KEYWORDS, channel_send_doc},
-    {"channel_recv",              _PyCFunction_CAST(channel_recv),
-     METH_VARARGS | METH_KEYWORDS, channel_recv_doc},
-    {"channel_close",             _PyCFunction_CAST(channel_close),
-     METH_VARARGS | METH_KEYWORDS, channel_close_doc},
-    {"channel_release",           _PyCFunction_CAST(channel_release),
-     METH_VARARGS | METH_KEYWORDS, channel_release_doc},
-    {"_channel_id",               _PyCFunction_CAST(channel__channel_id),
-     METH_VARARGS | METH_KEYWORDS, NULL},
-
     {NULL,                        NULL}           /* sentinel */
 };
 
@@ -2590,59 +792,71 @@ PyDoc_STRVAR(module_doc,
 "This module provides primitive operations to manage Python interpreters.\n\
 The 'interpreters' module provides a more convenient interface.");
 
-static struct PyModuleDef interpretersmodule = {
-    PyModuleDef_HEAD_INIT,
-    "_xxsubinterpreters",  /* m_name */
-    module_doc,            /* m_doc */
-    -1,                    /* m_size */
-    module_functions,      /* m_methods */
-    NULL,                  /* m_slots */
-    NULL,                  /* m_traverse */
-    NULL,                  /* m_clear */
-    NULL                   /* m_free */
-};
-
-
-PyMODINIT_FUNC
-PyInit__xxsubinterpreters(void)
+static int
+module_exec(PyObject *mod)
 {
-    if (_init_globals() != 0) {
-        return NULL;
+    /* Add exception types */
+    if (exceptions_init(mod) != 0) {
+        goto error;
     }
 
-    /* Initialize types */
-    if (PyType_Ready(&ChannelIDtype) != 0) {
-        return NULL;
+    // PyInterpreterID
+    if (PyModule_AddType(mod, &_PyInterpreterID_Type) < 0) {
+        goto error;
     }
 
-    /* Create the module */
-    PyObject *module = PyModule_Create(&interpretersmodule);
-    if (module == NULL) {
-        return NULL;
-    }
+    return 0;
 
-    /* Add exception types */
-    PyObject *ns = PyModule_GetDict(module);  // borrowed
-    if (interp_exceptions_init(ns) != 0) {
-        return NULL;
-    }
-    if (channel_exceptions_init(ns) != 0) {
-        return NULL;
-    }
+error:
+    return -1;
+}
 
-    /* Add other types */
-    Py_INCREF(&ChannelIDtype);
-    if (PyDict_SetItemString(ns, "ChannelID", (PyObject *)&ChannelIDtype) != 0) {
-        return NULL;
-    }
-    Py_INCREF(&_PyInterpreterID_Type);
-    if (PyDict_SetItemString(ns, "InterpreterID", (PyObject *)&_PyInterpreterID_Type) != 0) {
-        return NULL;
-    }
+static struct PyModuleDef_Slot module_slots[] = {
+    {Py_mod_exec, module_exec},
+    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+    {0, NULL},
+};
 
-    if (_PyCrossInterpreterData_RegisterClass(&ChannelIDtype, _channelid_shared)) {
-        return NULL;
-    }
+static int
+module_traverse(PyObject *mod, visitproc visit, void *arg)
+{
+    module_state *state = get_module_state(mod);
+    assert(state != NULL);
+    traverse_module_state(state, visit, arg);
+    return 0;
+}
+
+static int
+module_clear(PyObject *mod)
+{
+    module_state *state = get_module_state(mod);
+    assert(state != NULL);
+    clear_module_state(state);
+    return 0;
+}
 
-    return module;
+static void
+module_free(void *mod)
+{
+    module_state *state = get_module_state(mod);
+    assert(state != NULL);
+    clear_module_state(state);
+}
+
+static struct PyModuleDef moduledef = {
+    .m_base = PyModuleDef_HEAD_INIT,
+    .m_name = MODULE_NAME,
+    .m_doc = module_doc,
+    .m_size = sizeof(module_state),
+    .m_methods = module_functions,
+    .m_slots = module_slots,
+    .m_traverse = module_traverse,
+    .m_clear = module_clear,
+    .m_free = (freefunc)module_free,
+};
+
+PyMODINIT_FUNC
+PyInit__xxsubinterpreters(void)
+{
+    return PyModuleDef_Init(&moduledef);
 }