diff options
Diffstat (limited to 'Lib/concurrent/futures/thread.py')
| -rw-r--r-- | Lib/concurrent/futures/thread.py | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/Lib/concurrent/futures/thread.py b/Lib/concurrent/futures/thread.py index 2af31a106dd..ad6b4c20b56 100644 --- a/Lib/concurrent/futures/thread.py +++ b/Lib/concurrent/futures/thread.py @@ -80,7 +80,14 @@ def _worker(executor_reference, work_queue, initializer, initargs): work_item.run() # Delete references to object. See issue16284 del work_item + + # attempt to increment idle count + executor = executor_reference() + if executor is not None: + executor._idle_semaphore.release() + del executor continue + executor = executor_reference() # Exit if: # - The interpreter is shutting down OR @@ -133,6 +140,7 @@ class ThreadPoolExecutor(_base.Executor): self._max_workers = max_workers self._work_queue = queue.SimpleQueue() + self._idle_semaphore = threading.Semaphore(0) self._threads = set() self._broken = False self._shutdown = False @@ -178,12 +186,15 @@ class ThreadPoolExecutor(_base.Executor): submit.__doc__ = _base.Executor.submit.__doc__ def _adjust_thread_count(self): + # if idle threads are available, don't spin new threads + if self._idle_semaphore.acquire(timeout=0): + return + # When the executor gets lost, the weakref callback will wake up # the worker threads. def weakref_cb(_, q=self._work_queue): q.put(None) - # TODO(bquinlan): Should avoid creating new threads if there are more - # idle threads than items in the work queue. + num_threads = len(self._threads) if num_threads < self._max_workers: thread_name = '%s_%d' % (self._thread_name_prefix or self, |