By default the number of searches msearch executes is capped by the number of
nodes multiplied with the default size of the search threadpool. This default can be
overwritten by using the newly added `max_concurrent_searches` parameter.
Before the msearch api would concurrently execute all searches concurrently. If many large
msearch requests would be executed this could lead to some searches being rejected
while other searches in the msearch request would succeed.
The goal of this change is to avoid this exhausting of the search TP.
Closes#17926
Add `}` is statement delimiter but only in places where it is
otherwise a valid part of the syntax, specificall the end of a block.
We do this by matching but not consuming it. Antlr 4 doesn't have
syntax for this so we have to kind of hack it together by actually
matching the `}` and then seeking backwards in the token stream to
"unmatch" it. This looks reasonably efficient. Not perfect, but way
better than the alternatives.
I tried and rejected a few options:
1. Actually consuming the `}` and piping a boolean all through the
grammar from the last statement in a block to the delimiter. This
ended up being a rather large change and made the grammar way more
complicated.
2. Adding a semantic predicate to delimiter that just does the
lookahead. This doesn't work out well because it doesn't work (I
never figured out why) and because it generates an *amazing*
`adaptivePredict` which makes a super huge DFA. It looks super
inefficient.
Closes#18821
Writeable is better for immutable objects like TimeValue.
Switch to writeZLong which takes up less space than the original
writeLong in the majority of cases. Since we expect negative
TimeValues we shouldn't use
writeVLong.
Today we use a random source of UUIDs for assigning allocation IDs,
cluster IDs, etc. Yet, the source of randomness for this is not
reproducible in tests. Since allocation IDs end up as keys in hash maps,
this means allocation decisions and not reproducible in tests and this
leads to non-reproducible test failures. This commit modifies the
behavior of random UUIDs so that they are reproducible under tests. The
behavior for production code is not changed, we still use a true source
of secure randomness but under tests we just use a reproducible source
of non-secure randomness.
It is important to note that there is a test,
UUIDTests#testThreadedRandomUUID that relies on the UUIDs being truly
random. Thus, we have to modify the setup for this test to use a true
source of randomness. Thus, this is one test that will never be
reproducible but it is intentionally so.
Relates #18808
When trying to restore a snapshot of an index created in a previous
version of Elasticsearch, it is possible that empty shards in the
snapshot have a segments_N file that has an unsupported Lucene version
and a missing checksum. This leads to issues with restoring the
snapshot. This commit handles this special case by avoiding a restore
of a shard that has no data, since there is nothing to restore anyway.
Closes#18707
Testability of ICSS is achieved by introducing interfaces for IndicesService, IndexService and IndexShard. These interfaces extract all relevant methods used by ICSS (which do not deal directly with store) and give the possibility to easily mock all the store behavior away in the tests (and cuts down on dependencies).
Add Aggregation profiling initially only be for the shard phases (i.e. the reduce phase will not be profiled in this change)
This change refactors the query profiling class to extract abstract classes where it is useful for other profiler types to share code.
It presented as listeners never being called if you refresh at the same
time as the listener is added. It was caught rarely by
testConcurrentRefresh. mostly this is removing code and adding a comment:
```
Note that it is not safe for us to abort early if we haven't advanced the
position here because we set and read lastRefreshedLocation outside of a
synchronized block. We do that so that waiting for a refresh that has
already passed is just a volatile read but the cost is that any check
whether or not we've advanced the position will introduce a race between
adding the listener and the position check. We could work around this by
moving this assignment into the synchronized block below and double
checking lastRefreshedLocation in addOrNotify's synchronized block but
that doesn't seem worth it given that we already skip this process early
if there aren't any listeners to iterate.
```
Martijn van Groningen
Simon Willnauer
Christoph Büscher
Robert Muir
Robert Muir
Uwe Schindler
Nik Everett
Jack Conradson
Jason Tedor
Areek Zillur
Adrien Grand
Ali Beyad
Yannick Welsch
Colin Goodheart-Smithe
Jim Ferenczi
Daniel Mitterdorfer