============================================ #opendaylight-meeting: MD-SAL Ineterest Call ============================================ Meeting started by colindixon at 16:05:55 UTC. The full logs are available at http://meetings.opendaylight.org/opendaylight-meeting/2015/md_sal_ineterest_call/opendaylight-meeting-md_sal_ineterest_call.2015-07-14-16.05.log.html . Meeting summary --------------- * agenda (colindixon, 16:06:03) * spillover from clustering call (colindixon, 16:06:09) * planned things for beryllium (colindixon, 16:06:26) * proposed Beryliium MD-SAL tree APIs and sharding APIs (spillover from clustering call) (colindixon, 16:07:16) * if you’re interested, there is a recording for the clustering hackers call immediately before this one, which should give more context (colindixon, 16:09:41) * some problems from Helium: data change listeres on multiple subtrees don’t provide any ordering guarantees (colindixon, 16:10:13) * LINK: https://meetings.webex.com/collabs/url/S5R3Ri78y14q6I5wUliP1-2bEFqpAB1xhdb8KioOzYW00000 <-- The link to the recording from the Cluster Hacker's call (phrobb, 16:10:14) * also, affected shards were only known during writes to the transactions, not ahead of time (colindixon, 16:11:09) * also, no throttling or brachting of transactions (colindixon, 16:11:20) * also something about reads being a problem, but I dind’t quite catch it (colindixon, 16:11:29) * proposed solutions (colindixon, 16:11:32) * Datat treep API provides new features (colindixon, 16:11:42) * subtree-bound transactions which can only read/write to a given subtree (colindixon, 16:11:59) * all based on transaction chaining, better threading model, enforcement of a single writer (colindixon, 16:12:17) * tony goes into notable changes (colindixon, 16:13:24) * a subset is: ordered data change events, no need to do reads on data change notifications since the data is injected as part of the eveent (colindixon, 16:14:01) * controversially, these new APIs do away with read() and instead means that people can only get data via data change notifications (colindixon, 16:15:49) * moiz says that he things we’re going to need read(), tony says maybe, but it should be discouraged (colindixon, 16:16:16) * tom pantelis says he thinks read() will still be common (colindixon, 16:16:30) * there are three common patterns: producer, consumer, and transformer (colindixon, 16:16:47) * tom pantelis says it would be great if we could make it so that transactions only wrote to one shard, but he thinks problem not (colindixon, 16:23:10) * tony says, yeah that would require apps to be shard-aware, which we might or might not be able to assume that (colindixon, 16:24:25) * colindixon says that in practice, high-performance apps are very likely to be written to be shard aware anyway (colindixon, 16:24:58) * tony says that this proposal based on knowing what trees each clustered MD-SAL instance is listening to and writing too (based on the subtree-bound listeners and writers), this could be used to optimize shard leader and replica placement (colindixon, 16:28:21) * colindixon says that orthongonal to whether apps will choose to write cross-shard transactiions if they know (colindixon, 16:28:48) * moiz says won’t this wind up with every node being a replica of ever shard, which will also hurt perfomance (colindixon, 16:29:09) * tony points out that these APIs are designed to be low-level APIs, not designed for normal application writers (colindixon, 16:42:39) * there is a lot of discussion around how these APIs will be suitable or not for certain circumstances, e.g., OpenFlow (colindixon, 16:48:02) * moiz and tom pantelis would like to see this look at the OpenFlow use case for some idea of if we’re doing the right thing shere (colindixon, 16:48:30) * tony says that’s fine, but wants to make sure to focus on the broader ODL use cases (colindixon, 16:48:55) * ACTION: tony to post the HTML docs he was showing during the meeting and send it out (colindixon, 16:55:13) * beryllium dev forum topics (colindixon, 16:56:09) * LINK: https://wiki.opendaylight.org/view/Events:Be_Dev_Forum (colindixon, 16:56:16) * LINK: https://lists.opendaylight.org/pipermail/tsc/2015-July/003442.html moiz will post a lot of clustering topics (see this mail) (colindixon, 16:57:33) * some of what was covered here is likely to be part of that (colindixon, 16:58:18) * during the next week (colindixon, 16:59:50) * tony will post the preliminary release plans for yantools, controller, netconf and md-sal in the next week (colindixon, 17:00:08) * it sounds like next week, there are still issues that TomP and Moiz would like to go through here (colindixon, 17:01:42) * for example, Moiz thinks that we need to spend more time thinking about microsharding and how it interacts with data changes (colindixon, 17:02:02) * TomP asks if we want to do this in a waterfall style or agile style, there are lots of things to deal with here (colindixon, 17:03:46) Meeting ended at 17:10:35 UTC. People present (lines said) --------------------------- * colindixon (45) * odl_meetbot (5) * phrobb (1) Generated by `MeetBot`_ 0.1.4