Merge pull request #54 from python-thread/perf/thread-killing

Improving thread performance

src/thread/thread.py

@@ -11,6 +11,7 @@ class ParallelProcessing: ...
 
 import sys
 import time
+import ctypes
 import signal
 import threading
 from functools import wraps
@@ -32,7 +33,7 @@ class ParallelProcessing: ...
   HookFunction,
 )
 from typing_extensions import Generic, ParamSpec
-from typing import List, Callable, Optional, Union, Mapping, Sequence, Tuple, Generator
+from typing import List, Optional, Union, Mapping, Sequence, Tuple, Generator
 
 
 Threads: set['Thread'] = set()
@@ -56,7 +57,6 @@ class Thread(threading.Thread, Generic[_Target_P, _Target_T]):
 
   # threading.Thread stuff
   _initialized: bool
-  _run: Callable
 
   def __init__(
     self,
@@ -116,23 +116,29 @@ def _wrap_target(
     def wrapper(
       *args: _Target_P.args, **kwargs: _Target_P.kwargs
       ) -> Union[_Target_T, None]:
-      self.status = 'Running'
+      try:
+        self.status = 'Running'
 
-      global Threads
-      Threads.add(self)
+        global Threads
+        Threads.add(self)
 
-      try:
-        self._returned_value = target(*args, **kwargs)
-      except Exception as e:
-        if not any(isinstance(e, ignore) for ignore in self.ignore_errors):
-          self.status = 'Errored'
-          self.errors.append(e)
-          return
+        try:
+          self._returned_value = target(*args, **kwargs)
+        except Exception as e:
+          if not any(isinstance(e, ignore) for ignore in self.ignore_errors):
+            self.status = 'Errored'
+            self.errors.append(e)
+            return
+
+        self.status = 'Invoking hooks'
+        self._invoke_hooks()
+        Threads.remove(self)
+        self.status = 'Completed'
 
-      self.status = 'Invoking hooks'
-      self._invoke_hooks()
-      Threads.remove(self)
-      self.status = 'Completed'
+      except SystemExit:
+        self.status = 'Killed'
+        print('KILLED ident: %s' % self.ident)
+        return
 
     return wrapper
 
@@ -157,27 +163,6 @@ def _handle_exceptions(self) -> None:
     for e in self.errors:
       raise e
 
-  def global_trace(self, frame, event: str, arg) -> Optional[Callable]:
-    if event == 'call':
-      return self.local_trace
-
-  def local_trace(self, frame, event: str, arg):
-    if self.status == 'Kill Scheduled' and event == 'line':
-      print('KILLED ident: %s' % self.ident)
-      self.status = 'Killed'
-      raise SystemExit()
-    return self.local_trace
-
-  def _run_with_trace(self) -> None:
-    """This will replace `threading.Thread`'s `run()` method"""
-    if not self._run:
-      raise exceptions.ThreadNotInitializedError(
-        'Running `_run_with_trace` may cause unintended behaviour, run `start` instead'
-      )
-
-    sys.settrace(self.global_trace)
-    self._run()
-
   @property
   def result(self) -> _Target_T:
     """
@@ -274,17 +259,33 @@ def kill(self, yielding: bool = False, timeout: float = 5) -> bool:
 
     Returns
     -------
-    :returns bool: False if the it exceeded the timeout
+    :returns bool: False if the it exceeded the timeout without being killed
 
     Raises
     ------
+    ValueError: If the thread ident does not exist
     ThreadNotInitializedError: If the thread is not initialized
     ThreadNotRunningError: If the thread is not running
     """
     if not self.is_alive():
       raise exceptions.ThreadNotRunningError()
 
     self.status = 'Kill Scheduled'
+
+    res: int = ctypes.pythonapi.PyThreadState_SetAsyncExc(
+      ctypes.c_long(self.ident), ctypes.py_object(SystemExit)
+    )
+
+    if res == 0:
+      raise ValueError('Thread IDENT does not exist')
+    elif res > 1:
+      # Unexpected behaviour, something seriously went wrong
+      # https://docs.python.org/3/c-api/init.html#c.PyThreadState_SetAsyncExc
+      ctypes.pythonapi.PyThreadState_SetAsyncExc(self.ident, None)
+      raise SystemError(
+        f'Killing thread with ident [{self.ident}] failed!\nPyThreadState_SetAsyncExc returned: {res}'
+      )
+
     if not yielding:
       return True
 
@@ -308,8 +309,6 @@ def start(self) -> None:
     if self.is_alive():
       raise exceptions.ThreadStillRunningError()
 
-    self._run = self.run
-    self.run = self._run_with_trace
     super().start()