I have submitted a patch for https://issues.apache.org/jira/browse/CASSANDRA-14232. Looking for reviewers/feedback.
Thanks, Sumanth On Tue, Feb 13, 2018 at 2:06 PM, Benedict Elliott Smith <bened...@apache.org > wrote: > Sorry, I guess I'm tired. I thought this was discussing local write > latency. > > I'm surprised we have that and not coordinator write latency. > > Please do ignore me, I'm not sure why I got involved! > > On 13 February 2018 at 21:48, Benedict Elliott Smith <bened...@apache.org> > wrote: > > > For the record, I'm not certain there *is* a great deal of value in this. > > > > The read latency metrics are expected to vary a great deal, since the > > entire IO subsystem is involved. > > > > Writes, however, go straight to a memtable. They only block on IO if we > > exceed our commit log flush bandwidth for an extended period of time. We > > already have a metric for tracking this: CommitLog.WaitingOnCommit. > > > > I'm not saying there won't be any latency distribution, but it is > unlikely > > to be terribly interesting in very many situations. I can't off the top > of > > my head think of a good reason to consult this metric, that couldn't > better > > be answered elsewhere. > > > > > > > > On 13 February 2018 at 19:18, Sumanth Pasupuleti < > spasupul...@netflix.com. > > invalid> wrote: > > > >> Thanks Kurt and Chris for your valuable inputs. Created > >> https://issues.apache.org/jira/browse/CASSANDRA-14232; I shall start > >> working on this. > >> > >> Thanks, > >> Sumanth > >> > >> On Mon, Feb 12, 2018 at 7:43 AM, Chris Lohfink <clohf...@apple.com> > >> wrote: > >> > >> > It would be good to have it. Its not that its not there because its > >> > difficult or anything. I think its more that the read latency metric > was > >> > needed for speculative retry so it was added but the write side wasn't > >> > needed for that feature so wasn't added at same time. It would be very > >> > useful in determining the table that the coordinator writes are slow > to. > >> > > >> > Chris > >> > > >> > > On Feb 11, 2018, at 10:33 PM, kurt greaves <k...@instaclustr.com> > >> wrote: > >> > > > >> > > I've tried to search around for a reason for this in the past and > >> haven't > >> > > found one. I don't think it's a bad idea. Would be a helpful metric > to > >> > > diagnose internode networking issues - although I'll note that the > >> read > >> > > metric will also achieve this assuming you have enough reads to get > >> some > >> > > useful information out of it. > >> > > > >> > > On 9 February 2018 at 17:43, Sumanth Pasupuleti < > >> > > sumanth.pasupuleti...@gmail.com> wrote: > >> > > > >> > >> There is an existing CoordinatorReadLatency table metric. I am > >> looking > >> > to > >> > >> add CoordinatorWriteLatency table metric - however, before I > attempt > >> a > >> > shot > >> > >> at it, would like to know if anyone has context around why we > >> currently > >> > do > >> > >> not have such metric (while we have the read metric) - if someone > has > >> > >> already attempted and realized its a bad idea for some reason. > >> > >> > >> > >> Thanks, > >> > >> Sumanth > >> > >> > >> > > >> > > >> > --------------------------------------------------------------------- > >> > To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org > >> > For additional commands, e-mail: dev-h...@cassandra.apache.org > >> > > >> > > >> > > > > >
