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Benedict edited comment on CASSANDRA-8789 at 4/25/15 4:50 PM: -------------------------------------------------------------- bq. Gossip always contended with mutation *responses* and read responses. I suspect there may be an issue with nomenclature here. These statements made by Ariel are both true, but the internal nomenclature for both of these is REQUEST_RESPONSE. But to further clarify, the distinction has never been command/data, but between command/acknowledgement. Where acknowledgement in the case of a read request includes the entire data for serving that read request. was (Author: benedict): bq. Gossip always contended with mutation *responses* and read responses. I suspect there may be an issue with nomenclature here. These statements made by Ariel are both true, but the internal nomenclature for both of these is REQUEST_RESPONSE. > OutboundTcpConnectionPool should route messages to sockets by size not type > --------------------------------------------------------------------------- > > Key: CASSANDRA-8789 > URL: https://issues.apache.org/jira/browse/CASSANDRA-8789 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Ariel Weisberg > Assignee: Ariel Weisberg > Fix For: 3.0 > > Attachments: 8789.diff > > > I was looking at this trying to understand what messages flow over which > connection. > For reads the request goes out over the command connection and the response > comes back over the ack connection. > For writes the request goes out over the command connection and the response > comes back over the command connection. > Reads get a dedicated socket for responses. Mutation commands and responses > both travel over the same socket along with read requests. > Sockets are used uni-directional so there are actually four sockets in play > and four threads at each node (2 inbounded, 2 outbound). > CASSANDRA-488 doesn't leave a record of what the impact of this change was. > If someone remembers what situations were made better it would be good to > know. > I am not clear on when/how this is helpful. The consumer side shouldn't be > blocking so the only head of line blocking issue is the time it takes to > transfer data over the wire. > If message size is the cause of blocking issues then the current design mixes > small messages and large messages on the same connection retaining the head > of line blocking. > Read requests share the same connection as write requests (which are large), > and write acknowledgments (which are small) share the same connections as > write requests. The only winner is read acknowledgements. -- This message was sent by Atlassian JIRA (v6.3.4#6332)