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@javanna javanna commented Oct 10, 2024

With recent changes in Lucene around not forking execution when not necessary, we have removed the search worker thread pool in #111099. The worker thread pool had unlimited queue, and the fear was that we couuld have much more queueing on the search thread pool if we use it to parallelize execution across segments, because every shard would take up to a thread per slice when executing the query phase.

We have then introduced an additional conditional to stop parallelizing when there is a queue. That is perhaps a bit extreme, as it's a decision made when creating the searcher, while a queue may no longer be there once the search is executing. This has caused some benchmarks regressions, hence this commit removes the additional queue dependent conditional in order to perform additional benchmarks without it.

With recent changes in Lucene around not forking execution when not necessary, we have
removed the search worker thread pool in elastic#111099. The worker thread pool had unlimited queue,
and the fear was that we couuld have much more queueing on the search thread pool if we use
it to parallelize execution across segments, because every shard would take up to a thread
per slice when executing the query phase.

We have then introduced an additional conditional to stop parallelizing when there is a queue.
That is perhaps a bit extreme, as it's a decision made when creating the searcher, while a
queue may no longer be there once the search is executing. This has caused some benchmarks
regressions, hence this commit removes the additional queue dependent conditional in order
to perform additional benchmarks without it.
@javanna javanna added >non-issue :Search Foundations/Search Catch all for Search Foundations v9.0.0 labels Oct 10, 2024
@elasticsearchmachine elasticsearchmachine added the Team:Search Foundations Meta label for the Search Foundations team in Elasticsearch label Oct 10, 2024
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Pinging @elastic/es-search-foundations (Team:Search Foundations)

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Lets do it 🤞 :)

@javanna javanna merged commit 3d77894 into elastic:lucene_snapshot Oct 10, 2024
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@javanna javanna deleted the enhancement/executor_queue_is_empty branch October 10, 2024 15:57
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>non-issue :Search Foundations/Search Catch all for Search Foundations Team:Search Foundations Meta label for the Search Foundations team in Elasticsearch v9.0.0

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3 participants