On Thu, Oct 26, 2017 at 11:34 AM, Meier, Caleb <[email protected]> wrote: > Hello Fluo Devs, > > We have implemented an incremental query evaluation service for Apache Rya > that leverages Apache Fluo. We’ve been doing some benchmarking and we’ve > found that the Accumulo Tablet servers for the Fluo table are falling behind > pretty quickly for our application. We’ve tried splitting the Accumulo Table > so that we have more Tablet Servers, but that doesn’t really buy us too much. > Our application is fairly scan intensive—we have a metadata framework in > place that allows us to pass query results through the query tree, and each > observer needs to look up metadata to determine which observer to route its > data to after processing. To give you some indication of our scan rates, our > Join Observer does about 6 lookups, builds a scanner to do one RowColumn > restricted scan, and then does many writes. So an obvious way to alleviate > the burden on the TableServer is to cut down on the number of scans. > > One approach that we are considering is to import all of our metadata into > memory. Essentially, each Observer would need access to an in memory > metadata cache. We’re considering using the Observer context, but this cache > needs to be mutable because a user needs to be able to register new queries. > Is it possible to update the context, or would we need to restart the > application to do that? I guess other options would be to create a static > cache for each Observer that stores the metadata, or to store it in > Zookeeper. Have any of you devs ever had create a solution to share state > between Observers that doesn’t rely on the Fluo table?
If you did want to cache something between observers this would require using static stuff in 1.0. In 1.1.0 Fluo introduced a new API for creating observers called the ObserverProvider. Using this new API, static stuff would not be required. The cache could be created in the ObserverProvider and passed to the Observers. The 1.1.0 release notes give an overview of the new API. http://fluo.apache.org/release/fluo-1.1.0-incubating/#new-api-for-configuring-observers > > In addition to cutting down on the scan rate, are there any other approaches > that you would consider? I assume that the problem lies primarily with how > we’ve implemented our application, but I’m also wondering if there is > anything we can do from a configuration point of view to reduce the burden on > the Tablet servers. Would reducing the number of workers/worker threads to > cut down on the number of times a single observation is processed be helpful? > It seems like this approach would cut out some redundant scans as well, but > it might be more of a second order optimization. In general, any insight that > you might have on this problem would be greatly appreciated. > > Sincerely, > Caleb Meier > > Caleb A. Meier, Ph.D. > Senior Software Engineer ♦ Analyst > Parsons Corporation > 1911 N. Fort Myer Drive, Suite 800 ♦ Arlington, VA 22209 > Office: (703)797-3066 > [email protected]<mailto:[email protected]> ♦ > www.parsons.com<https://webportal.parsons.com/,DanaInfo=www.parsons.com+> >
