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
The regex tests are formatted with blocks for readability. Previously,
they were formatted using folded style blocks (e.g. using `>`). Folded
blocks convert newlines into spaces. This is problematic for our regex,
since comments can only be terminated with a newline.
Effectively, anything after a comment will be commented out, making many
of the regex "silently pass".
This commit replaces them with scalar-style blocks (e.g. using `|`), which
treats newlines as significant, and thus correctly terminates comments
inside the regex.
Also fixes a regex test (`cat.thread_pool/10_basic.yaml`) that started
to fail after the block was fixed. The test was missing a `\s+` before
the closing newline.