Charles-François Natali added the comment:
I just realized that using DefaultSelector isn't optimal for Connection:
It's fine for forkserver, since it's a long lived process, but for
Connection.poll(), this means that it'll use epoll or kqueue: which
means allocating a new epoll/kqueue object for each conn.poll().
That's a couple syscalls more (epoll_create()/epoll_ctl()/close()),
but most important it uses an extra FD per connection.
The attached patch uses PollSelector if available, otherwise SelectSelector.
----------
Added file: http://bugs.python.org/file31629/connection_selector.diff
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue18934>
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diff -r 3070fdd58645 Lib/multiprocessing/connection.py
--- a/Lib/multiprocessing/connection.py Fri Sep 06 13:08:08 2013 -0400
+++ b/Lib/multiprocessing/connection.py Fri Sep 06 20:45:04 2013 +0200
@@ -878,13 +878,21 @@
import selectors
+ # poll/select have the advantage of not requiring any extra file
+ # descriptor, contrarily to epoll/kqueue. Also, they're a bit faster for
+ # short-lived polling, since they require a single syscall.
+ if hasattr(selectors, 'PollSelector'):
+ _WaitSelector = selectors.PollSelector
+ else:
+ _WaitSelector = selectors.SelectSelector
+
def wait(object_list, timeout=None):
'''
Wait till an object in object_list is ready/readable.
Returns list of those objects in object_list which are ready/readable.
'''
- with selectors.DefaultSelector() as selector:
+ with _WaitSelector() as selector:
for obj in object_list:
selector.register(obj, selectors.EVENT_READ)
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