Reindexing performance in gerrit is very slow when running on larger
multicore servers.
When you have multiple index threads putting content into LUCENE index,
it falls behind and starts to throttle the content being merged.
Updated to allow us to configure and override the default AutoDetected
configuration of the Lucene index queue and the threads it uses to
merge (add/update) data into the index.
The auto detection in the Lucene index by default does the following:
1) It throttles the index writing to less than 20Mb/s.
2) On storage arrays it detects them as being slow spinning rust, and not
as faster SSD type systems. This in turn limits the lucene merge to only
1 thread and a limited queue size of 6.
These settings allow the control of each of the auto detected settings
and adjustment to suit your own server and storage performance.
Bug: Issue 11356
Change-Id: Ie1be338f5a31f5ad572d9fdec19775b2dd09aa5f
8fb5db5b0d