Warmers are now barely useful and will be removed in 3.0. Note that this only
removes the warmer API and query-based warmers. We still have warmers internally
for eg. global ordinals.
Close#15607
This adds an API for force merging lucene segments. The `/_optimize` API is now
deprecated and replaced by the `/_forcemerge` API, which has all the same flags
and action, just a different name.
Today, Elasticsearch has a separate merge thread pool checking once
per second (by default) if any merges are necessary, but this is no
longer necessary since we can and do now tell Lucene's
ConcurrentMergeScheduler never to "hard pause" threads when merges
fall behind, since we do our own index throttling.
This change goes back to letting Lucene launch merges as needed, and
removes these two expert settings:
index.merge.force_async_merge
index.merge.async_interval
Now merges kick off immediately instead of waiting up to 1 second
before running.
Closes#8643
By default active, rejected and queue thread statistics are included for the index, bulk and search thread pool.
Other thread statistics of other thread pools can be included via the `h` query string parameter.
Closes#4907
Martijn van Groningen
Adrien Grand
Lee Hinman
Clinton Gormley
Michael McCandless
Chris Earle
Luca Cavanna