On 24 October 2013 18:01, John Vines <[email protected]> wrote: > Accumulo isn't going to run in YARN,
Well it can if you want it too - what we are doing with hoya is giving the option to do without changing the core application. Some applications (e.g. Samza) are being written from the ground up for YARN , so they have an Application Master that manages requesting containers, running code in it, while the code knows it is in an isolated container (currently: transient dir and cgroup-limited RAM, more limits coming). But you don't need a complete rewrite to gain from running under YAR. Accumulo is very suited to running in YARN; if you look at the list of things we need from an app to get it to play, it's pretty much complete: https://github.com/hortonworks/hoya/blob/develop/src/site/markdown/app_needs.md A key benefit is how you can react to failures. Until now: tserver down: log it, balance workload. {master, monitor, gc} down: page someone. In YARN, all failures become something for the automation to handle: log it, ask for new instance, balance work back when it is up. You can downgrade the one-per-application node to that of logged statistics rather than events that need immediate human intervention, Detecting a process failure is trivial: it exits and the container does too. Harder is more byzantine failure modes -what would be ideal would just be able to go from the ZK data to identifying which service instance needs to be let go. What is useful here is getting all the locations of things like web URLs out of ZK too -as you can't predetermine the host they will be on, and if you fix the port you may have binding problems. > it's just a matter of replacing MR > compatibility with YARN compatibility. > > MRv1 code should work with MR-on-YARN : if not, file a bug report What you do get long term is the option of talking to other services running in the cluster -and for them to talk to you -- CONFIDENTIALITY NOTICE NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any printing, copying, dissemination, distribution, disclosure or forwarding of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and delete it from your system. Thank You.
