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gh-142654: show the clear error message when sampling on an unknown PID in tachyon (#142655)

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Co-authored-by: Pablo Galindo Salgado <pablogsal@gmail.com>
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Keming 2025-12-17 22:15:22 +08:00 • committed by GitHub
parent 1fc3039d71
commit d4095f25e8
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8 changed files with 104 additions and 43 deletions
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7
Lib/profiling/sampling/__main__.py
View file

@ -46,6 +46,7 @@
"""
from .cli import main
from .errors import SamplingUnknownProcessError, SamplingModuleNotFoundError, SamplingScriptNotFoundError
def handle_permission_error():
"""Handle PermissionError by displaying appropriate error message."""
@ -64,3 +65,9 @@ def handle_permission_error():
main()
except PermissionError:
handle_permission_error()
except SamplingUnknownProcessError as err:
print(f"Tachyon cannot find the process: {err}", file=sys.stderr)
sys.exit(1)
except (SamplingModuleNotFoundError, SamplingScriptNotFoundError) as err:
print(f"Tachyon cannot find the target: {err}", file=sys.stderr)
sys.exit(1)

9
Lib/profiling/sampling/cli.py
View file

@ -10,7 +10,8 @@
import time
from contextlib import nullcontext
from .sample import sample, sample_live
from .errors import SamplingUnknownProcessError, SamplingModuleNotFoundError, SamplingScriptNotFoundError
from .sample import sample, sample_live, _is_process_running
from .pstats_collector import PstatsCollector
from .stack_collector import CollapsedStackCollector, FlamegraphCollector
from .heatmap_collector import HeatmapCollector
@ -743,6 +744,8 @@ def main():
def _handle_attach(args):
"""Handle the 'attach' command."""
if not _is_process_running(args.pid):
raise SamplingUnknownProcessError(args.pid)
# Check if live mode is requested
if args.live:
_handle_live_attach(args, args.pid)
@ -792,13 +795,13 @@ def _handle_run(args):
added_cwd = True
try:
if importlib.util.find_spec(args.target) is None:
sys.exit(f"Error: Module not found: {args.target}")
raise SamplingModuleNotFoundError(args.target)
finally:
if added_cwd:
sys.path.remove(cwd)
else:
if not os.path.exists(args.target):
sys.exit(f"Error: Script not found: {args.target}")
raise SamplingScriptNotFoundError(args.target)
# Check if live mode is requested
if args.live:

19
Lib/profiling/sampling/errors.py Normal file
View file

@ -0,0 +1,19 @@
"""Custom exceptions for the sampling profiler."""
class SamplingProfilerError(Exception):
"""Base exception for sampling profiler errors."""
class SamplingUnknownProcessError(SamplingProfilerError):
def __init__(self, pid):
self.pid = pid
super().__init__(f"Process with PID '{pid}' does not exist.")
class SamplingScriptNotFoundError(SamplingProfilerError):
def __init__(self, script_path):
self.script_path = script_path
super().__init__(f"Script '{script_path}' not found.")
class SamplingModuleNotFoundError(SamplingProfilerError):
def __init__(self, module_name):
self.module_name = module_name
super().__init__(f"Module '{module_name}' not found.")

72
Lib/profiling/sampling/sample.py
View file

@ -34,24 +34,30 @@ def __init__(self, pid, sample_interval_usec, all_threads, *, mode=PROFILING_MOD
self.all_threads = all_threads
self.mode = mode # Store mode for later use
self.collect_stats = collect_stats
if _FREE_THREADED_BUILD:
self.unwinder = _remote_debugging.RemoteUnwinder(
self.pid, all_threads=self.all_threads, mode=mode, native=native, gc=gc,
opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
cache_frames=True, stats=collect_stats
)
else:
only_active_threads = bool(self.all_threads)
self.unwinder = _remote_debugging.RemoteUnwinder(
self.pid, only_active_thread=only_active_threads, mode=mode, native=native, gc=gc,
opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
cache_frames=True, stats=collect_stats
)
try:
self.unwinder = self._new_unwinder(native, gc, opcodes, skip_non_matching_threads)
except RuntimeError as err:
raise SystemExit(err) from err
# Track sample intervals and total sample count
self.sample_intervals = deque(maxlen=100)
self.total_samples = 0
self.realtime_stats = False
def _new_unwinder(self, native, gc, opcodes, skip_non_matching_threads):
if _FREE_THREADED_BUILD:
unwinder = _remote_debugging.RemoteUnwinder(
self.pid, all_threads=self.all_threads, mode=self.mode, native=native, gc=gc,
opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
cache_frames=True, stats=self.collect_stats
)
else:
unwinder = _remote_debugging.RemoteUnwinder(
self.pid, only_active_thread=bool(self.all_threads), mode=self.mode, native=native, gc=gc,
opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
cache_frames=True, stats=self.collect_stats
)
return unwinder
def sample(self, collector, duration_sec=10, *, async_aware=False):
sample_interval_sec = self.sample_interval_usec / 1_000_000
running_time = 0
@ -86,7 +92,7 @@ def sample(self, collector, duration_sec=10, *, async_aware=False):
collector.collect_failed_sample()
errors += 1
except Exception as e:
if not self._is_process_running():
if not _is_process_running(self.pid):
break
raise e from None
@ -148,22 +154,6 @@ def sample(self, collector, duration_sec=10, *, async_aware=False):
f"({(expected_samples - num_samples) / expected_samples * 100:.2f}%)"
)
def _is_process_running(self):
if sys.platform == "linux" or sys.platform == "darwin":
try:
os.kill(self.pid, 0)
return True
except ProcessLookupError:
return False
elif sys.platform == "win32":
try:
_remote_debugging.RemoteUnwinder(self.pid)
except Exception:
return False
return True
else:
raise ValueError(f"Unsupported platform: {sys.platform}")
def _print_realtime_stats(self):
"""Print real-time sampling statistics."""
if len(self.sample_intervals) < 2:
@ -279,6 +269,28 @@ def _print_unwinder_stats(self):
print(f" {ANSIColors.YELLOW}Stale cache invalidations: {stale_invalidations}{ANSIColors.RESET}")
def _is_process_running(pid):
if pid <= 0:
return False
if os.name == "posix":
try:
os.kill(pid, 0)
return True
except ProcessLookupError:
return False
except PermissionError:
# EPERM means process exists but we can't signal it
return True
elif sys.platform == "win32":
try:
_remote_debugging.RemoteUnwinder(pid)
except Exception:
return False
return True
else:
raise ValueError(f"Unsupported platform: {sys.platform}")
def sample(
pid,
collector,

26
Lib/test/test_profiling/test_sampling_profiler/test_cli.py
View file

@ -16,6 +16,7 @@
from test.support import is_emscripten, requires_remote_subprocess_debugging
from profiling.sampling.cli import main
from profiling.sampling.errors import SamplingScriptNotFoundError, SamplingModuleNotFoundError, SamplingUnknownProcessError
class TestSampleProfilerCLI(unittest.TestCase):
@ -203,12 +204,12 @@ def test_cli_mutually_exclusive_pid_script(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("sys.stderr", io.StringIO()) as mock_stderr,
self.assertRaises(SystemExit) as cm,
self.assertRaises(SamplingScriptNotFoundError) as cm,
):
main()
# Verify the error is about the non-existent script
self.assertIn("12345", str(cm.exception.code))
self.assertIn("12345", str(cm.exception))
def test_cli_no_target_specified(self):
# In new CLI, must specify a subcommand
@ -436,6 +437,7 @@ def test_cli_default_collapsed_filename(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -475,6 +477,7 @@ def test_cli_custom_output_filenames(self):
for test_args, expected_filename, expected_format in test_cases:
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -513,6 +516,7 @@ def test_argument_parsing_basic(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -534,6 +538,7 @@ def test_sort_options(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -547,6 +552,7 @@ def test_async_aware_flag_defaults_to_running(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -562,6 +568,7 @@ def test_async_aware_with_async_mode_all(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -576,6 +583,7 @@ def test_async_aware_default_is_none(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
main()
@ -697,14 +705,20 @@ def test_async_aware_incompatible_with_all_threads(self):
def test_run_nonexistent_script_exits_cleanly(self):
"""Test that running a non-existent script exits with a clean error."""
with mock.patch("sys.argv", ["profiling.sampling.cli", "run", "/nonexistent/script.py"]):
with self.assertRaises(SystemExit) as cm:
with self.assertRaisesRegex(SamplingScriptNotFoundError, "Script '[\\w/.]+' not found."):
main()
self.assertIn("Script not found", str(cm.exception.code))
@unittest.skipIf(is_emscripten, "subprocess not available")
def test_run_nonexistent_module_exits_cleanly(self):
"""Test that running a non-existent module exits with a clean error."""
with mock.patch("sys.argv", ["profiling.sampling.cli", "run", "-m", "nonexistent_module_xyz"]):
with self.assertRaises(SystemExit) as cm:
with self.assertRaisesRegex(SamplingModuleNotFoundError, "Module '[\\w/.]+' not found."):
main()
self.assertIn("Module not found", str(cm.exception.code))
def test_cli_attach_nonexistent_pid(self):
fake_pid = "99999"
with mock.patch("sys.argv", ["profiling.sampling.cli", "attach", fake_pid]):
with self.assertRaises(SamplingUnknownProcessError) as cm:
main()
self.assertIn(fake_pid, str(cm.exception))

8
Lib/test/test_profiling/test_sampling_profiler/test_integration.py
View file

@ -17,7 +17,7 @@
import profiling.sampling.sample
from profiling.sampling.pstats_collector import PstatsCollector
from profiling.sampling.stack_collector import CollapsedStackCollector
from profiling.sampling.sample import SampleProfiler
from profiling.sampling.sample import SampleProfiler, _is_process_running
except ImportError:
raise unittest.SkipTest(
"Test only runs when _remote_debugging is available"
@ -602,7 +602,7 @@ def test_sample_target_module(self):
@requires_remote_subprocess_debugging()
class TestSampleProfilerErrorHandling(unittest.TestCase):
def test_invalid_pid(self):
with self.assertRaises((OSError, RuntimeError)):
with self.assertRaises((SystemExit, PermissionError)):
collector = PstatsCollector(sample_interval_usec=100, skip_idle=False)
profiling.sampling.sample.sample(-1, collector, duration_sec=1)
@ -638,7 +638,7 @@ def test_is_process_running(self):
sample_interval_usec=1000,
all_threads=False,
)
self.assertTrue(profiler._is_process_running())
self.assertTrue(_is_process_running(profiler.pid))
self.assertIsNotNone(profiler.unwinder.get_stack_trace())
subproc.process.kill()
subproc.process.wait()
@ -647,7 +647,7 @@ def test_is_process_running(self):
)
# Exit the context manager to ensure the process is terminated
self.assertFalse(profiler._is_process_running())
self.assertFalse(_is_process_running(profiler.pid))
self.assertRaises(
ProcessLookupError, profiler.unwinder.get_stack_trace
)

4
Lib/test/test_profiling/test_sampling_profiler/test_modes.py
View file

@ -252,6 +252,7 @@ def test_gil_mode_validation(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
try:
@ -313,6 +314,7 @@ def test_gil_mode_cli_argument_parsing(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
try:
@ -432,6 +434,7 @@ def test_exception_mode_validation(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
try:
@ -493,6 +496,7 @@ def test_exception_mode_cli_argument_parsing(self):
with (
mock.patch("sys.argv", test_args),
mock.patch("profiling.sampling.cli._is_process_running", return_value=True),
mock.patch("profiling.sampling.cli.sample") as mock_sample,
):
try:

2
Misc/NEWS.d/next/Library/2025-12-13-10-34-59.gh-issue-142654.fmm974.rst Normal file
View file

@ -0,0 +1,2 @@
Show the clearer error message when using ``profiling.sampling`` on an
unknown PID.