gh-151496: Use process groups in test_dtrace (#151512)

Create a new process group to run bpftrace commands, so it's possible
to kill also child processes on timeout.

diff --git a/Lib/test/test_dtrace.py b/Lib/test/test_dtrace.py
index 6286b6d21b572e3e64bbab66b617afc55cdec5bb..592f59d77f92217604fde312c992da53e56d2184 100644 (file)
--- a/Lib/test/test_dtrace.py
+++ b/Lib/test/test_dtrace.py
@@ -1,6 +1,7 @@
 import dis
 import os.path
 import re
+import signal
 import subprocess
 import sys
 import sysconfig
@@ -50,6 +51,24 @@ def normalize_trace_output(output):
         )
 
 
+USE_PROCESS_GROUP = (hasattr(os, "setsid") and hasattr(os, "killpg"))
+
+def create_process_group(*args, **kwargs):
+    if USE_PROCESS_GROUP:
+        kwargs['start_new_session'] = True
+    return subprocess.Popen(*args, **kwargs)
+
+def kill_process_group(proc):
+    if USE_PROCESS_GROUP:
+        try:
+            os.killpg(proc.pid, signal.SIGKILL)
+        except ProcessLookupError:
+            pass
+    else:
+        proc.kill()
+    proc.communicate()  # Clean up
+
+
 class TraceBackend:
     EXTENSION = None
     COMMAND = None
@@ -205,7 +224,7 @@ gc__done:1""",
         program = self.PROGRAMS[name].format(python=sys.executable)
 
         try:
-            proc = subprocess.Popen(
+            proc = create_process_group(
                 ["bpftrace", "-e", program, "-c", " ".join(subcommand)],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
@@ -213,7 +232,7 @@ gc__done:1""",
             )
             stdout, stderr = proc.communicate(timeout=60)
         except subprocess.TimeoutExpired:
-            proc.kill()
+            kill_process_group(proc)
             raise AssertionError("bpftrace timed out")
         except (FileNotFoundError, PermissionError) as e:
             raise unittest.SkipTest(f"bpftrace not available: {e}")
@@ -243,7 +262,7 @@ gc__done:1""",
         # Check if bpftrace is available and can attach to USDT probes
         program = f'usdt:{sys.executable}:python:function__entry {{ printf("probe: success\\n"); exit(); }}'
         try:
-            proc = subprocess.Popen(
+            proc = create_process_group(
                 ["bpftrace", "-e", program, "-c", f"{sys.executable} -c pass"],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
@@ -251,8 +270,7 @@ gc__done:1""",
             )
             stdout, stderr = proc.communicate(timeout=10)
         except subprocess.TimeoutExpired:
-            proc.kill()
-            proc.communicate()  # Clean up
+            kill_process_group(proc)
             raise unittest.SkipTest("bpftrace timed out during usability check")
         except OSError as e:
             raise unittest.SkipTest(f"bpftrace not available: {e}")