From 2d70b1149ac37c2482eb760e2af1cbc05f5b0d8b Mon Sep 17 00:00:00 2001 From: Matt Page Date: Mon, 7 Jul 2025 17:08:46 -0700 Subject: [PATCH 1/2] Include instrumentation when creating new copies of the bytecode Previously, we assumed that instrumentation would happen for all copies of the bytecode if the instrumentation version on the code object didn't match the per-interpreter instrumentation version. That assumption was incorrect: instrumentation will exit early if there are no new "events," even if there is an instrumentation version mismatch. To fix this, include the instrumented opcodes when creating new copies of the bytecode, rather than replacing them with their uninstrumented variants. I don't think we have to worry about races between instrumentation and creating new copies of the bytecode: instrumentation and new bytecode creation cannot happen concurrently. Instrumentation requires that either the world is stopped or the code object's per-object lock is held and new bytecode creation requires holding the code object's per-object lock. --- .../test_free_threading/test_monitoring.py | 141 ++++++++++++++++++ Objects/codeobject.c | 19 ++- 2 files changed, 159 insertions(+), 1 deletion(-) diff --git a/Lib/test/test_free_threading/test_monitoring.py b/Lib/test/test_free_threading/test_monitoring.py index a480e398722c33..c3d0a2bcea5c17 100644 --- a/Lib/test/test_free_threading/test_monitoring.py +++ b/Lib/test/test_free_threading/test_monitoring.py @@ -2,10 +2,12 @@ environment to verify things are thread-safe in a free-threaded build""" import sys +import threading import time import unittest import weakref +from contextlib import contextmanager from sys import monitoring from test.support import threading_helper from threading import Thread, _PyRLock, Barrier @@ -192,6 +194,16 @@ def during_threads(self): self.set = not self.set +class TraceBuf: + def __init__(self): + self.traces = [] + self.traces_lock = threading.Lock() + + def append(self, trace): + with self.traces_lock: + self.traces.append(trace) + + @threading_helper.requires_working_threading() class MonitoringMisc(MonitoringTestMixin, TestCase): def register_callback(self, barrier): @@ -246,6 +258,135 @@ def f(): finally: sys.settrace(None) + def test_toggle_setprofile_no_new_events(self): + # gh-136396: Make sure that profile functions are called for newly + # created threads when profiling is toggled but the set of monitoring + # events doesn't change + traces = [] + + def profiler(frame, event, arg): + traces.append((frame.f_code.co_name, event, arg)) + + def a(x, y): + return b(x, y) + + def b(x, y): + return max(x, y) + + sys.setprofile(profiler) + try: + a(1, 2) + finally: + sys.setprofile(None) + traces.clear() + + def thread_main(x, y): + sys.setprofile(profiler) + try: + a(x, y) + finally: + sys.setprofile(None) + t = Thread(target=thread_main, args=(100, 200)) + t.start() + t.join() + + expected = [ + ("a", "call", None), + ("b", "call", None), + ("b", "c_call", max), + ("b", "c_return", max), + ("b", "return", 200), + ("a", "return", 200), + ("thread_main", "c_call", sys.setprofile), + ] + self.assertEqual(traces, expected) + + def observe_threads(self, observer, buf): + def in_child(ident): + return ident + + def child(ident): + with observer(): + in_child(ident) + + def in_parent(ident): + return ident + + def parent(barrier, ident): + barrier.wait() + with observer(): + t = Thread(target=child, args=(ident,)) + t.start() + t.join() + in_parent(ident) + + num_threads = 5 + barrier = Barrier(num_threads) + threads = [] + for i in range(num_threads): + t = Thread(target=parent, args=(barrier, i)) + t.start() + threads.append(t) + for t in threads: + t.join() + + for i in range(num_threads): + self.assertIn(("in_parent", "return", i), buf.traces) + self.assertIn(("in_child", "return", i), buf.traces) + + def test_profile_threads(self): + buf = TraceBuf() + + def profiler(frame, event, arg): + buf.append((frame.f_code.co_name, event, arg)) + + @contextmanager + def profile(): + sys.setprofile(profiler) + try: + yield + finally: + sys.setprofile(None) + + self.observe_threads(profile, buf) + + def test_trace_threads(self): + buf = TraceBuf() + + def tracer(frame, event, arg): + buf.append((frame.f_code.co_name, event, arg)) + return tracer + + @contextmanager + def trace(): + sys.settrace(tracer) + try: + yield + finally: + sys.settrace(None) + + self.observe_threads(trace, buf) + + def test_monitor_threads(self): + buf = TraceBuf() + + def monitor_py_return(code, off, retval): + buf.append((code.co_name, "return", retval)) + + monitoring.register_callback( + self.tool_id, monitoring.events.PY_RETURN, monitor_py_return + ) + + monitoring.set_events( + self.tool_id, monitoring.events.PY_RETURN + ) + + @contextmanager + def noop(): + yield + + self.observe_threads(noop, buf) + if __name__ == "__main__": unittest.main() diff --git a/Objects/codeobject.c b/Objects/codeobject.c index ba178abc0c071e..42e021679b583f 100644 --- a/Objects/codeobject.c +++ b/Objects/codeobject.c @@ -3330,12 +3330,29 @@ _PyCodeArray_New(Py_ssize_t size) return arr; } +// Get the underlying code unit, leaving instrumentation +static _Py_CODEUNIT +deopt_code_unit(PyCodeObject *code, int i) +{ + _Py_CODEUNIT *src_instr = _PyCode_CODE(code) + i; + _Py_CODEUNIT inst = { + .cache = FT_ATOMIC_LOAD_UINT16_RELAXED(*(uint16_t *)src_instr)}; + int opcode = inst.op.code; + if (opcode < MIN_INSTRUMENTED_OPCODE) { + inst.op.code = _PyOpcode_Deopt[opcode]; + assert(inst.op.code < MIN_SPECIALIZED_OPCODE); + } + // JIT should not be enabled with free-threading + assert(inst.op.code != ENTER_EXECUTOR); + return inst; +} + static void copy_code(_Py_CODEUNIT *dst, PyCodeObject *co) { int code_len = (int) Py_SIZE(co); for (int i = 0; i < code_len; i += _PyInstruction_GetLength(co, i)) { - dst[i] = _Py_GetBaseCodeUnit(co, i); + dst[i] = deopt_code_unit(co, i); } _PyCode_Quicken(dst, code_len, 1); } From 59b96cc4188db15ea049a7345199d57e4b9431e7 Mon Sep 17 00:00:00 2001 From: Matt Page Date: Thu, 10 Jul 2025 15:53:26 -0700 Subject: [PATCH 2/2] Add blurb --- .../2025-07-10-15-53-16.gh-issue-136525.xAko0e.rst | 2 ++ 1 file changed, 2 insertions(+) create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-07-10-15-53-16.gh-issue-136525.xAko0e.rst diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-07-10-15-53-16.gh-issue-136525.xAko0e.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-07-10-15-53-16.gh-issue-136525.xAko0e.rst new file mode 100644 index 00000000000000..f28eb2ca3b71e8 --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-07-10-15-53-16.gh-issue-136525.xAko0e.rst @@ -0,0 +1,2 @@ +Fix issue where per-thread bytecode was not instrumented for newly created +threads.