On Fri, Aug 3, 2012 at 10:50 AM, Yousuf Fauzan <yousuffau...@gmail.com> wrote:
> The query fails with the following error
> <<"{\"phase\":1,\"error\":\"{{{badmatch,[]},[{riak_kv_js_manager,needs_reload,2},{riak_kv_js_manager,handle_call,3},...Hi, Yousuf. I think there may be a race between a Javascript VM marking itself idle and the same VM getting the message that its manager has died. Could you please check in your Riak logs for an error similar to: 16:32:10.693 [error] Supervisor riak_kv_sup had child riak_kv_js_map started with riak_kv_js_manager:start_link(riak_kv_js_map, 8) at <0.284.0> exit with reason killed in context child_terminated The important part to look for is the first bit about "Supervisor riak_kv_sup had child riak_kv_js_map started with riak_kv_js_manager:start_link". If that happened, then the error your seeing is an old VM trying to mark itself idle with a new manager that doesn't know about it. I'll work up a patch to solve this issue. *Why* that manager exited, if that is indeed what you find in your logs, is another question, and may have to do with many JS VMs crashing suddenly. Such situations are often linked to high memory pressure, in my experience. > Also, MR is quite slow. Is there a way to speed things up? The biggest speedup in MR performance often comes from rewriting Javascript phases in Erlang. It's annoying, yes, but it avoids the costs of JSON (de-)serialization and inter-VM communication. Reduce phases, in particular, also benefit from ensuring that your function is actually *reducing* (not accumulating an ever-growing result on each invocation), and from tuning reduce_phase_batch_size or even using reduce_phase_only_1. (http://wiki.basho.com/MapReduce-Implementation.html#Configuration-Tuning-for-Reduce-Phases) Hope that helps, Bryan _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
