diff options
Diffstat (limited to 'Lib/concurrent/futures/process.py')
| -rw-r--r-- | Lib/concurrent/futures/process.py | 23 |
1 files changed, 6 insertions, 17 deletions
diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py index 39fadcc..4c39500 100644 --- a/Lib/concurrent/futures/process.py +++ b/Lib/concurrent/futures/process.py @@ -59,19 +59,6 @@ import itertools import sys import traceback -# Workers are created as daemon threads and processes. This is done to allow the -# interpreter to exit when there are still idle processes in a -# ProcessPoolExecutor's process pool (i.e. shutdown() was not called). However, -# allowing workers to die with the interpreter has two undesirable properties: -# - The workers would still be running during interpreter shutdown, -# meaning that they would fail in unpredictable ways. -# - The workers could be killed while evaluating a work item, which could -# be bad if the callable being evaluated has external side-effects e.g. -# writing to a file. -# -# To work around this problem, an exit handler is installed which tells the -# workers to exit when their work queues are empty and then waits until the -# threads/processes finish. _threads_wakeups = weakref.WeakKeyDictionary() _global_shutdown = False @@ -107,6 +94,12 @@ def _python_exit(): for t, _ in items: t.join() +# Register for `_python_exit()` to be called just before joining all +# non-daemon threads. This is used instead of `atexit.register()` for +# compatibility with subinterpreters, which no longer support daemon threads. +# See bpo-39812 for context. +threading._register_atexit(_python_exit) + # Controls how many more calls than processes will be queued in the call queue. # A smaller number will mean that processes spend more time idle waiting for # work while a larger number will make Future.cancel() succeed less frequently @@ -306,9 +299,7 @@ class _ExecutorManagerThread(threading.Thread): # {5: <_WorkItem...>, 6: <_WorkItem...>, ...} self.pending_work_items = executor._pending_work_items - # Set this thread to be daemonized super().__init__() - self.daemon = True def run(self): # Main loop for the executor manager thread. @@ -732,5 +723,3 @@ class ProcessPoolExecutor(_base.Executor): self._executor_manager_thread_wakeup = None shutdown.__doc__ = _base.Executor.shutdown.__doc__ - -atexit.register(_python_exit) |