Created
February 28, 2015 09:58
-
-
Save mikelambert/6615b37fa326c1008a4b to your computer and use it in GitHub Desktop.
A hacky attempt to fix the RPC starvation problems I encountered with the NDB eventloops.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| # This attempts to force a FIFO ordering on RPC execution in the eventloop (as opposed to random RPC execution) | |
| RPC_ORDERING = True | |
| if RPC_ORDERING: | |
| import collections | |
| from google.appengine.ext.ndb import eventloop | |
| class OrderedEventLoop(eventloop.EventLoop): | |
| def __init__(self): | |
| super(OrderedEventLoop, self).__init__() | |
| self.rpcs = collections.OrderedDict() | |
| eventloop.EventLoop = OrderedEventLoop | |
| from google.appengine.api import apiproxy_stub_map | |
| from google.appengine.api import apiproxy_rpc | |
| @classmethod | |
| def __check_one(cls, rpcs): | |
| rpc = None | |
| logging.debug('Pending RPCs: %s', rpcs) | |
| for rpc in rpcs: | |
| assert isinstance(rpc, cls), repr(rpc) | |
| # Original: | |
| # state = rpc.__rpc.state | |
| # Revised: | |
| state = rpc.state | |
| if state == apiproxy_rpc.RPC.FINISHING: | |
| # Original: | |
| # rpc.__call_user_callback() | |
| # Revised: | |
| rpc.wait() | |
| logging.debug('Found finished RPC: %s', rpc) | |
| return rpc, None | |
| assert state != apiproxy_rpc.RPC.IDLE, repr(rpc) | |
| logging.debug('No finished RPCs, going to wait for first RPC: %s', rpcs[0]) | |
| # This is the important changed line in this whole function: | |
| # We want to return the oldest RPC to execute, not a random one. | |
| return None, rpcs[0] | |
| assert hasattr(apiproxy_stub_map.UserRPC, '_UserRPC__check_one') | |
| apiproxy_stub_map.UserRPC._UserRPC__check_one = __check_one |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment