Handle process exiting during sampling

Author: lkollar

Lib/profile/sample.py

@@ -1,9 +1,11 @@
 import argparse
 import _remote_debugging
+import os
 import pstats
 import statistics
-import time
+import sys
 import sysconfig
+import time
 from collections import deque
 from _colorize import ANSIColors
 
@@ -47,8 +49,14 @@ def sample(self, collector, duration_sec=10):
                 try:
                     stack_frames = self.unwinder.get_stack_trace()
                     collector.collect(stack_frames)
-                except (RuntimeError, UnicodeDecodeError, OSError):
+                except ProcessLookupError:
+                    break
+                except (RuntimeError, UnicodeDecodeError, MemoryError):
                     errors += 1
+                except Exception as e:
+                    if not self._is_process_running():
+                        break
+                    raise e from None
 
                 # Track actual sampling intervals for real-time stats
                 if num_samples > 0:
@@ -89,6 +97,22 @@ def sample(self, collector, duration_sec=10):
                 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:

Lib/test/test_sample_profiler.py

@@ -23,12 +23,15 @@
 
 try:
     from _remote_debugging import PROCESS_VM_READV_SUPPORTED
+    import _remote_debugging
 except ImportError:
     raise unittest.SkipTest(
         "Test only runs when _remote_debugging is available"
     )
 else:
     import profile.sample
+    from profile.sample import SampleProfiler
+
 
 
 class MockFrameInfo:
@@ -1600,6 +1603,30 @@ def test_invalid_output_format_with_mocked_profiler(self):
                 "Invalid output format: unknown_format", str(cm.exception)
             )
 
+    def test_is_process_running(self):
+        with (test_subprocess("import time; time.sleep(0.2)") as proc,
+              mock.patch("_remote_debugging.RemoteUnwinder") as mock_unwinder_class):
+                mock_unwinder_class.return_value = mock.MagicMock()
+                profiler = SampleProfiler(pid=proc.pid, sample_interval_usec=1000, all_threads=False)
+
+                self.assertTrue(profiler._is_process_running())
+                proc.wait()
+                self.assertFalse(profiler._is_process_running())
+
+    @unittest.skipUnless(sys.platform == "linux", "Only valid on Linux")
+    def test_esrch_signal_handling(self):
+        with test_subprocess("import time; time.sleep(0.1)") as proc:
+            unwinder = _remote_debugging.RemoteUnwinder(proc.pid)
+            initial_trace = unwinder.get_stack_trace()
+            self.assertIsNotNone(initial_trace)
+
+            # Wait for the process to die and try to get another trace
+            proc.wait()
+
+            with self.assertRaises(ProcessLookupError):
+                unwinder.get_stack_trace()
+
+
 
 class TestSampleProfilerCLI(unittest.TestCase):
     def test_cli_collapsed_format_validation(self):

Python/remote_debug.h

@@ -982,6 +982,9 @@ _Py_RemoteDebug_ReadRemoteMemory(proc_handle_t *handle, uintptr_t remote_address
                 return read_remote_memory_fallback(handle, remote_address, len, dst);
             }
             PyErr_SetFromErrno(PyExc_OSError);
+            if (errno == ESRCH) {
+                return -1;
+            }
             _set_debug_exception_cause(PyExc_OSError,
                 "process_vm_readv failed for PID %d at address 0x%lx "
                 "(size %zu, partial read %zd bytes): %s",