gh-143040: Exit taychon live mode gracefully and display profiled script errors #143101

mgmacias95 · 2025-12-23T15:53:28Z

This script shows the error trace when a profiled script (or python module) in the live mode fails.

Some output examples:

When running a script that fails inmediately, the live mode won't even start and you'll see the traceback directly instead:

mgmacias@mgmacias:~/cpython$ cat failing_script.py 
1/0
mgmacias@mgmacias:~/cpython$ ./python -m profiling.sampling run --live -d999999 failing_script.py 
No samples collected - process 1464940 exited before profiling could begin.
Traceback (most recent call last):
  File "<frozen runpy>", line 196, in _run_module_as_main
  File "<frozen runpy>", line 87, in _run_code
  File "/home/mgmacias/cpython/Lib/profiling/sampling/_sync_coordinator.py", line 256, in <module>
    main()
    ~~~~^^
  File "/home/mgmacias/cpython/Lib/profiling/sampling/_sync_coordinator.py", line 249, in main
    _execute_script(script_path, script_args, cwd)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgmacias/cpython/Lib/profiling/sampling/_sync_coordinator.py", line 196, in _execute_script
    exec(code, main_module.__dict__)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/mgmacias/cpython/failing_script.py", line 1, in <module>
    1/0
    ~^~
ZeroDivisionError: division by zero

When running a test that doesn't exist, you will see a brief profiled information and when exiting the live mode you'll see this traceback:

mgmacias@mgmacias:~/cpython$ ./python -m profiling.sampling run --live -d999999 -m test test_dfgdfg
test test_dfgdfg crashed -- Traceback (most recent call last):
  File "/home/mgmacias/cpython/Lib/test/libregrtest/single.py", line 210, in _runtest_env_changed_exc
    _load_run_test(result, runtests)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/mgmacias/cpython/Lib/test/libregrtest/single.py", line 155, in _load_run_test
    test_mod = importlib.import_module(module_name)
  File "/home/mgmacias/cpython/Lib/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1303, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1276, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1240, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'test.test_dfgdfg'

Issue: Tachion's TUI sometimes does not work on the first try #143040

pablogsal

We need to rebase/merge main to fix conflicts

pablogsal

Looks like we have some problems with macOS and unclosed files (I think your subprocess call needs to be a context manager).

pablogsal · 2025-12-24T14:09:12Z

This may be enough (didn;t check):

diff --git a/Lib/profiling/sampling/cli.py b/Lib/profiling/sampling/cli.py
index 4d2d5b37453..bb7e629a993 100644
--- a/Lib/profiling/sampling/cli.py
+++ b/Lib/profiling/sampling/cli.py
@@ -1061,13 +1061,14 @@ def _handle_live_run(args):
         process.wait()
         # Read any stderr output (tracebacks, errors, etc.)
         if process.stderr:
-            try:
-                stderr = process.stderr.read()
-                if stderr:
-                    print(stderr.decode(), file=sys.stderr)
-            except (OSError, ValueError):
-                # Ignore errors if pipe is already closed
-                pass
+            with process.stderr:
+                try:
+                    stderr = process.stderr.read()
+                    if stderr:
+                        print(stderr.decode(), file=sys.stderr)
+                except (OSError, ValueError):
+                    # Ignore errors if pipe is already closed
+                    pass
 
 
 def _handle_replay(args):
diff --git a/Lib/test/test_profiling/test_sampling_profiler/test_live_collector_ui.py b/Lib/test/test_profiling/test_sampling_profiler/test_live_collector_ui.py
index b492b471f82..dec850a83e9 100644
--- a/Lib/test/test_profiling/test_sampling_profiler/test_live_collector_ui.py
+++ b/Lib/test/test_profiling/test_sampling_profiler/test_live_collector_ui.py
@@ -839,7 +839,7 @@ def mock_init_curses_side_effect(self, n_times, mock_self, stdscr):
 
     @unittest.skipIf(is_emscripten, "subprocess not available")
     def test_run_failed_module_live(self):
-        """Test that running a existing module that fails exists with clean error."""
+        """Test that running a existing module that fails exits with clean error."""
 
         args = [
             "profiling.sampling.cli", "run", "--live", "-m", "test",
@@ -857,18 +857,19 @@ def test_run_failed_module_live(self):
             mock.patch('sys.stderr', new=io.StringIO()) as fake_stderr
         ):
             main()
-            self.assertStartsWith(
-                fake_stderr.getvalue(),
-                '\x1b[31mtest test_asdasd crashed -- Traceback (most recent call last):'
-            )
+            stderr = fake_stderr.getvalue()
+            # Check that error output contains the crash message and traceback
+            # (without checking exact ANSI codes which vary by environment)
+            self.assertIn('test_asdasd', stderr)
+            self.assertIn('Traceback (most recent call last):', stderr)
 
     @unittest.skipIf(is_emscripten, "subprocess not available")
     def test_run_failed_script_live(self):
         """Test that running a failing script exits with clean error."""
-        script = tempfile.NamedTemporaryFile(suffix=".py")
+        script = tempfile.NamedTemporaryFile(suffix=".py", delete=False)
         self.addCleanup(close_and_unlink, script)
         script.write(b'1/0\n')
-        script.seek(0)
+        script.flush()
 
         args = ["profiling.sampling.cli", "run", "--live", script.name]
 
@@ -884,13 +885,10 @@ def test_run_failed_script_live(self):
         ):
             main()
             stderr = fake_stderr.getvalue()
-            self.assertIn(
-                'sample(s) collected (minimum 200 required for TUI)', stderr
-            )
-            self.assertEndsWith(
-                stderr,
-                'ZeroDivisionError\x1b[0m: \x1b[35mdivision by zero\x1b[0m\n\n'
-            )
+            # Check that output contains the error information
+            # (without checking exact ANSI codes which vary by environment)
+            self.assertIn('ZeroDivisionError', stderr)
+            self.assertIn('division by zero', stderr)
 
 
 if __name__ == "__main__":

mgmacias95 added 3 commits December 23, 2025 15:22

fix(tachyon): Exit gracefully and display profiled script errors

28b512e

fix conflicts

db38449

.

0af647c

mgmacias95 requested a review from pablogsal as a code owner December 23, 2025 15:53

bedevere-app bot added the awaiting review label Dec 23, 2025

bedevere-app bot mentioned this pull request Dec 23, 2025

Tachion's TUI sometimes does not work on the first try #143040

Open

mgmacias95 added 2 commits December 23, 2025 23:48

only run the tests if curses is enabled

d7d5e87

add env cleanup

79e3121

pablogsal reviewed Dec 24, 2025

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gh-143040: Exit taychon live mode gracefully and display profiled script errors #143101

gh-143040: Exit taychon live mode gracefully and display profiled script errors #143101

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