python · Fidget-Spinner · Jun 13, 2025 · Jun 13, 2025 · markshannon · Jun 13, 2025
diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
diff --git a/Include/internal/pycore_pyerrors.h b/Include/internal/pycore_pyerrors.h
@@ -207,6 +207,9 @@ extern int _PyUnicodeError_GetParams(
     Py_ssize_t *slen,
     int as_bytes);
 
+
+int _PyErr_CheckSignalsWithoutGC(void);
+
 #ifdef __cplusplus
 }
 #endif

diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-06-13-15-42-40.gh-issue-135474.3t52if.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-13-15-42-40.gh-issue-135474.3t52if.rst
@@ -0,0 +1 @@
+The garbage collector no longer runs in the middle of a long-running int addition/subtraction/multiplication. This should have little real effect on real-world code, while simplifying CPython's internal invariants. This may also speed up long-running int operations.
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
@@ -1788,6 +1788,26 @@ PyErr_CheckSignals(void)
     return _PyErr_CheckSignalsTstate(tstate);
 }
 
+/* Same as PyErr_CheckSignals but does not run the GC.
+   This can be safely used if you are certain that no allocation
+   is done inside the long-running C code.
+ */
+int
+_PyErr_CheckSignalsWithoutGC(void)
+{
+    PyThreadState *tstate = _PyThreadState_GET();
+
+#if defined(Py_REMOTE_DEBUG) && defined(Py_SUPPORTS_REMOTE_DEBUG)
+    _PyRunRemoteDebugger(tstate);
+#endif
+
+    if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
+        return 0;
+    }
+
+    return _PyErr_CheckSignalsTstate(tstate);
+}
+
 
 /* Declared in cpython/pyerrors.h */
 int

diff --git a/Objects/longobject.c b/Objects/longobject.c
@@ -113,7 +113,7 @@ maybe_small_long(PyLongObject *v)
 
 #define SIGCHECK(PyTryBlock)                    \
     do {                                        \
-        if (PyErr_CheckSignals()) PyTryBlock    \
+        if (_PyErr_CheckSignalsWithoutGC()) PyTryBlock    \
     } while(0)
 
 /* Normalize (remove leading zeros from) an int object.

diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
@@ -635,6 +635,9 @@ def has_error_without_pop(op: parser.CodeDef) -> bool:
     "_PyLong_IsNegative",
     "_PyLong_IsNonNegativeCompact",
     "_PyLong_IsZero",
+    "_PyLong_Add",
+    "_PyLong_Multiply",
+    "_PyLong_Subtract",
     "_PyManagedDictPointer_IsValues",
     "_PyObject_GC_IS_SHARED",
     "_PyObject_GC_IS_TRACKED",
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		The garbage collector no longer runs in the middle of a long-running int addition/subtraction/multiplication. This should have little real effect on real-world code, while simplifying CPython's internal invariants. This may also speed up long-running int operations.