Thank you, you’re right - only one of the four cores is hitting 100%. This is the correct answer. The bottleneck is CPU exacerbated by an absence of parallelisation.
> On 3 Mar 2017, at 12:32, Toke Eskildsen <t...@kb.dk> wrote: > > On Thu, 2017-03-02 at 15:39 +0000, Caruana, Matthew wrote: >> Thank you. The question remains however, if this is such a hefty >> operation then why is it walking to the destination instead of >> running, so to speak? > > We only do optimize on an old Solr 4.10 setup, but for that we have > plenty of experience. At least for single-shard, and at least for most > of the work, optimize is a single-threaded process: It takes us ~8 > hours to optimize a ~900GB shard using SSDs, with 1 CPU-core at near > 100% and the other ones not doing anything. > > The machine load number is a bit fuzzy, but if you do a top doing > optimization, my guess is that you will see the same thing as we do: > Only 1 CPU-core working. > -- > Toke Eskildsen, Royal Danish Library
