python · markshannon · Jun 20, 2025 · Jun 20, 2025 · Jun 20, 2025 · Jun 20, 2025
diff --git a/Doc/library/dis.rst b/Doc/library/dis.rst
@@ -78,6 +78,7 @@ the following command can be used to display the disassembly of
      3           LOAD_GLOBAL              1 (len + NULL)
                  LOAD_FAST_BORROW         0 (alist)
                  CALL                     1
                 CHECK_PERIODIC
                  RETURN_VALUE
 
 (The "2" is a line number).
@@ -217,6 +218,7 @@ Example:
     LOAD_GLOBAL
     LOAD_FAST_BORROW
     CALL
+    CHECK_PERIODIC
     RETURN_VALUE
 
 
@@ -1751,6 +1753,15 @@ iterations of the loop.
    .. versionadded:: 3.11
 
 
+.. opcode:: CHECK_PERIODIC
+
+   Checks the eval breaker and performs periodic tasks if the eval breaker is set.
+   Tasks inlcude switching threads and performing GC amongst others.
+   All :opcode:`CALL` instructions must be followed by :opcode:`CHECK_PERIODIC`.
+
+   .. versionadded:: 3.14
+
+
 .. opcode:: HAVE_ARGUMENT
 
    This is not really an opcode.  It identifies the dividing line between

diff --git a/Include/internal/pycore_magic_number.h b/Include/internal/pycore_magic_number.h
@@ -281,6 +281,7 @@ Known values:
     Python 3.15a1 3651 (Simplify LOAD_CONST)
     Python 3.15a1 3652 (Virtual iterators)
     Python 3.15a1 3653 (Fix handling of opcodes that may leave operands on the stack when optimizing LOAD_FAST)
+    Python 3.15a2 3654 (Add CHECK_PERIODIC opcode)
 
 
     Python 3.16 will start with 3700
@@ -294,7 +295,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3653
+#define PYC_MAGIC_NUMBER 3654
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
diff --git a/Include/internal/pycore_optimizer.h b/Include/internal/pycore_optimizer.h
@@ -293,6 +293,7 @@ typedef struct _JitOptContext {
     char done;
     char out_of_space;
     bool contradiction;
+    bool can_skip_periodic;
     // The current "executing" frame.
     _Py_UOpsAbstractFrame *frame;
     _Py_UOpsAbstractFrame frames[MAX_ABSTRACT_FRAME_DEPTH];

diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h