gh-97922: Run the GC only on eval breaker (#97920)

2 files changed, 37 insertions, 3 deletions

diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 97cb6e6..75832e9 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -2253,6 +2253,20 @@ PyObject_IS_GC(PyObject *obj)
 }
 
 void
+_Py_ScheduleGC(PyInterpreterState *interp)
+{
+    GCState *gcstate = &interp->gc;
+    if (gcstate->collecting == 1) {
+        return;
+    }
+    struct _ceval_state *ceval = &interp->ceval;
+    if (!_Py_atomic_load_relaxed(&ceval->gc_scheduled)) {
+        _Py_atomic_store_relaxed(&ceval->gc_scheduled, 1);
+        _Py_atomic_store_relaxed(&ceval->eval_breaker, 1);
+    }
+}
+
+void
 _PyObject_GC_Link(PyObject *op)
 {
     PyGC_Head *g = AS_GC(op);
@@ -2269,12 +2283,19 @@ _PyObject_GC_Link(PyObject *op)
         !gcstate->collecting &&
         !_PyErr_Occurred(tstate))
     {
-        gcstate->collecting = 1;
-        gc_collect_generations(tstate);
-        gcstate->collecting = 0;
+        _Py_ScheduleGC(tstate->interp);
     }
 }
 
+void
+_Py_RunGC(PyThreadState *tstate)
+{
+    GCState *gcstate = &tstate->interp->gc;
+    gcstate->collecting = 1;
+    gc_collect_generations(tstate);
+    gcstate->collecting = 0;
+}
+
 static PyObject *
 gc_alloc(size_t basicsize, size_t presize)
 {
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 0f30b4d..b85d6d1 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -1798,6 +1798,19 @@ int
 PyErr_CheckSignals(void)
 {
     PyThreadState *tstate = _PyThreadState_GET();
+
+    /* Opportunistically check if the GC is scheduled to run and run it
+       if we have a request. This is done here because native code needs
+       to call this API if is going to run for some time without executing
+       Python code to ensure signals are handled. Checking for the GC here
+       allows long running native code to clean cycles created using the C-API
+       even if it doesn't run the evaluation loop */
+    struct _ceval_state *interp_ceval_state = &tstate->interp->ceval;
+    if (_Py_atomic_load_relaxed(&interp_ceval_state->gc_scheduled)) {
+        _Py_atomic_store_relaxed(&interp_ceval_state->gc_scheduled, 0);
+        _Py_RunGC(tstate);
+    }
+
     if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
         return 0;
     }