Use a simpler and more straightforward method to terminate the process tree

Author: weilycoder

cyaron/io.py

@@ -7,10 +7,10 @@
 from __future__ import absolute_import
 import os
 import re
+import signal
 import subprocess
 import tempfile
-import psutil
-from typing import Union, overload, Optional, List
+from typing import Union, overload, Optional, List, cast
 from io import IOBase
 from . import log
 from .utils import list_like, make_unicode
@@ -91,6 +91,7 @@ def __init__(  # type: ignore
             # if the dir "./io" not found it will be created
         """
         self.__closed = False
+        self.input_file = cast(IOBase, None)
         self.output_file = None
         if file_prefix is not None:
             # legacy mode
@@ -230,20 +231,13 @@ def __clear(self, file: IOBase, pos: int = 0):
         file.seek(pos)
 
     @staticmethod
-    def _kill_process_and_children(pid: int):
-        try:
-            parent = psutil.Process(pid)
-            while True:
-                children = parent.children()
-                if not children:
-                    break
-                for child in children:
-                    IO._kill_process_and_children(child.pid)
-            parent.kill()
-        except psutil.NoSuchProcess:
-            pass
-        except psutil.AccessDenied:
-            pass
+    def _kill_process_and_children(proc: subprocess.Popen):
+        if os.name == "posix":
+            os.killpg(os.getpgid(proc.pid), signal.SIGKILL)
+        elif os.name == "nt":
+            os.system(f"TASKKILL /F /T /PID {proc.pid} > nul")
+        else:
+            proc.kill()  # Not currently supported
 
     def input_write(self, *args, **kwargs):
         """
@@ -304,13 +298,14 @@ def output_gen(self,
             stdin=self.input_file.fileno(),
             stdout=subprocess.PIPE,
             universal_newlines=replace_EOL,
+            preexec_fn=os.setsid if os.name == "posix" else None,
         )
 
         try:
             output, _ = proc.communicate(timeout=time_limit)
         except subprocess.TimeoutExpired:
-            # proc.kill() # didn't work because `shell=True`.
-            self._kill_process_and_children(proc.pid)
+            # proc.kill()  # didn't work because `shell=True`.
+            self._kill_process_and_children(proc)
             raise
         else:
             if replace_EOL:

cyaron/tests/io_test.py

@@ -76,10 +76,12 @@ def test_output_gen(self):
 
     def test_output_gen_time_limit_exceeded(self):
         with captured_output():
+            TIMEOUT = 0.02
+            WAIT_TIME = 0.4  # If the wait time is too short, an error may occur
             with open("long_time.py", "w", encoding="utf-8") as f:
                 f.write("import time, os\n"
                         "fn = input()\n"
-                        "time.sleep(0.1)\n"
+                        f"time.sleep({WAIT_TIME})\n"
                         "os.remove(fn)\n")
 
             with IO("test_gen.in", "test_gen.out") as test:
@@ -89,8 +91,8 @@ def test_output_gen_time_limit_exceeded(self):
                 with self.assertRaises(subprocess.TimeoutExpired):
                     test.input_writeln(abs_input_filename)
                     test.output_gen(f'"{sys.executable}" long_time.py',
-                                    time_limit=0.05)
-                time.sleep(0.1)
+                                    time_limit=TIMEOUT)
+                time.sleep(WAIT_TIME)
                 try:
                     os.remove(input_filename)
                 except FileNotFoundError:
@@ -133,10 +135,7 @@ def test_make_dirs(self):
 
         mkdir_false = False
         try:
-            with IO(
-                    "./automkdir_false/data.in",
-                    "./automkdir_false/data.out",
-            ):
+            with IO("./automkdir_false/data.in", "./automkdir_false/data.out"):
                 pass
         except FileNotFoundError:
             mkdir_false = True

poetry.lock

@@ -10,7 +10,6 @@ readme = "README.md"
 python = ">=3.6"
 xeger = "^0.4.0"
 colorful = "^0.5.6"
-psutil = "^6.1.0"
 
 
 [build-system]

pyproject.toml

@@ -7,6 +7,5 @@ isolated_build = true
 deps = 
   xeger
   colorful
-  psutil
 commands = python unit_test.py
 allowlist_externals = poetry