Merged revisions 77794 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r77794 | jesse.noller | 2010-01-26 22:05:57 -0500 (Tue, 26 Jan 2010) | 1 line
Issue #6963: Added maxtasksperchild argument to multiprocessing.Pool
........
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index d3ecc9b..6271b86 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -42,7 +42,8 @@
# Code run by worker processes
#
-def worker(inqueue, outqueue, initializer=None, initargs=()):
+def worker(inqueue, outqueue, initializer=None, initargs=(), maxtasks=None):
+ assert maxtasks is None or (type(maxtasks) == int and maxtasks > 0)
put = outqueue.put
get = inqueue.get
if hasattr(inqueue, '_writer'):
@@ -52,7 +53,8 @@
if initializer is not None:
initializer(*initargs)
- while 1:
+ completed = 0
+ while maxtasks is None or (maxtasks and completed < maxtasks):
try:
task = get()
except (EOFError, IOError):
@@ -69,6 +71,8 @@
except Exception as e:
result = (False, e)
put((job, i, result))
+ completed += 1
+ debug('worker exiting after %d tasks' % completed)
#
# Class representing a process pool
@@ -80,11 +84,15 @@
'''
Process = Process
- def __init__(self, processes=None, initializer=None, initargs=()):
+ def __init__(self, processes=None, initializer=None, initargs=(),
+ maxtasksperchild=None):
self._setup_queues()
self._taskqueue = queue.Queue()
self._cache = {}
self._state = RUN
+ self._maxtasksperchild = maxtasksperchild
+ self._initializer = initializer
+ self._initargs = initargs
if processes is None:
try:
@@ -95,16 +103,18 @@
if initializer is not None and not hasattr(initializer, '__call__'):
raise TypeError('initializer must be a callable')
+ self._processes = processes
self._pool = []
- for i in range(processes):
- w = self.Process(
- target=worker,
- args=(self._inqueue, self._outqueue, initializer, initargs)
- )
- self._pool.append(w)
- w.name = w.name.replace('Process', 'PoolWorker')
- w.daemon = True
- w.start()
+ self._repopulate_pool()
+
+ self._worker_handler = threading.Thread(
+ target=Pool._handle_workers,
+ args=(self, )
+ )
+ self._worker_handler.daemon = True
+ self._worker_handler._state = RUN
+ self._worker_handler.start()
+
self._task_handler = threading.Thread(
target=Pool._handle_tasks,
@@ -125,10 +135,48 @@
self._terminate = Finalize(
self, self._terminate_pool,
args=(self._taskqueue, self._inqueue, self._outqueue, self._pool,
- self._task_handler, self._result_handler, self._cache),
+ self._worker_handler, self._task_handler,
+ self._result_handler, self._cache),
exitpriority=15
)
+ def _join_exited_workers(self):
+ """Cleanup after any worker processes which have exited due to reaching
+ their specified lifetime. Returns True if any workers were cleaned up.
+ """
+ cleaned = False
+ for i in reversed(range(len(self._pool))):
+ worker = self._pool[i]
+ if worker.exitcode is not None:
+ # worker exited
+ debug('cleaning up worker %d' % i)
+ worker.join()
+ cleaned = True
+ del self._pool[i]
+ return cleaned
+
+ def _repopulate_pool(self):
+ """Bring the number of pool processes up to the specified number,
+ for use after reaping workers which have exited.
+ """
+ for i in range(self._processes - len(self._pool)):
+ w = self.Process(target=worker,
+ args=(self._inqueue, self._outqueue,
+ self._initializer,
+ self._initargs, self._maxtasksperchild)
+ )
+ self._pool.append(w)
+ w.name = w.name.replace('Process', 'PoolWorker')
+ w.daemon = True
+ w.start()
+ debug('added worker')
+
+ def _maintain_pool(self):
+ """Clean up any exited workers and start replacements for them.
+ """
+ if self._join_exited_workers():
+ self._repopulate_pool()
+
def _setup_queues(self):
from .queues import SimpleQueue
self._inqueue = SimpleQueue()
@@ -218,6 +266,13 @@
return result
@staticmethod
+ def _handle_workers(pool):
+ while pool._worker_handler._state == RUN and pool._state == RUN:
+ pool._maintain_pool()
+ time.sleep(0.1)
+ debug('worker handler exiting')
+
+ @staticmethod
def _handle_tasks(taskqueue, put, outqueue, pool):
thread = threading.current_thread()
@@ -332,16 +387,19 @@
debug('closing pool')
if self._state == RUN:
self._state = CLOSE
+ self._worker_handler._state = CLOSE
self._taskqueue.put(None)
def terminate(self):
debug('terminating pool')
self._state = TERMINATE
+ self._worker_handler._state = TERMINATE
self._terminate()
def join(self):
debug('joining pool')
assert self._state in (CLOSE, TERMINATE)
+ self._worker_handler.join()
self._task_handler.join()
self._result_handler.join()
for p in self._pool:
@@ -358,10 +416,11 @@
@classmethod
def _terminate_pool(cls, taskqueue, inqueue, outqueue, pool,
- task_handler, result_handler, cache):
+ worker_handler, task_handler, result_handler, cache):
# this is guaranteed to only be called once
debug('finalizing pool')
+ worker_handler._state = TERMINATE
task_handler._state = TERMINATE
taskqueue.put(None) # sentinel
@@ -373,10 +432,12 @@
result_handler._state = TERMINATE
outqueue.put(None) # sentinel
+ # Terminate workers which haven't already finished.
if pool and hasattr(pool[0], 'terminate'):
debug('terminating workers')
for p in pool:
- p.terminate()
+ if p.exitcode is None:
+ p.terminate()
debug('joining task handler')
task_handler.join(1e100)
@@ -388,6 +449,11 @@
debug('joining pool workers')
for p in pool:
p.join()
+ for w in pool:
+ if w.exitcode is None:
+ # worker has not yet exited
+ debug('cleaning up worker %d' % w.pid)
+ w.join()
#
# Class whose instances are returned by `Pool.apply_async()`