Address concurrency issue in top hits aggregation #106990
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Hi @javanna, I've created a changelog YAML for you. |
elasticsearchmachine
added
the
Team:Analytics
|
Pinging @elastic/es-analytical-engine (Team:Analytics) |
salvatore-campagna
approved these changes
Apr 2, 2024
|
LGTM, thank you. I will close PR #106910 as a result of having this one. |
martijnvg
approved these changes
Apr 2, 2024
|
@martijnvg I already updated |
javanna
commented
Apr 2, 2024
...er/src/internalClusterTest/java/org/elasticsearch/search/aggregations/metrics/TopHitsIT.java
Show resolved
Hide resolved
javanna
commented
Apr 2, 2024
server/src/main/java/org/elasticsearch/search/aggregations/metrics/TopHitsAggregator.java
Outdated
Show resolved
Hide resolved
iverase
approved these changes
Apr 4, 2024
|
Thanks all for the reviews and help! |
javanna
added a commit
to javanna/elasticsearch
that referenced
this pull request
Apr 4, 2024
Top hits aggregation runs the fetch phase concurrently when the query phase is executed across multiple slices. This is problematic as the fetch phase does not support concurrent execution yet. The core of the issue is that the search execution context is shared across slices, which call setLookupProviders against it concurrently, setting each time different instances of preloaded source and field lookup providers. This makes us cross streams between slices, and hit lucene assertions that ensure that stored fields loaded from a certain thread are not read from a different thread. We have not hit this before because the problem revolves around SearchLookup which is used by runtime fields. TopHitsIT is the main test we have for top hits agg, but it uses a mock script engine which bypasses painless and SearchLookup.
javanna
added a commit
that referenced
this pull request
Apr 4, 2024
Top hits aggregation runs the fetch phase concurrently when the query phase is executed across multiple slices. This is problematic as the fetch phase does not support concurrent execution yet. The core of the issue is that the search execution context is shared across slices, which call setLookupProviders against it concurrently, setting each time different instances of preloaded source and field lookup providers. This makes us cross streams between slices, and hit lucene assertions that ensure that stored fields loaded from a certain thread are not read from a different thread. We have not hit this before because the problem revolves around SearchLookup which is used by runtime fields. TopHitsIT is the main test we have for top hits agg, but it uses a mock script engine which bypasses painless and SearchLookup.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Top hits aggregation runs the fetch phase concurrently when the query phase is executed across multiple slices. This is problematic as the fetch phase does not support concurrent execution yet.
The core of the issue is that the search execution context is shared across slices, which call
setLookupProvidersagainst it concurrently, setting each time different instances of preloaded source and field lookup providers. This makes us cross streams between slices, and hit lucene assertions that ensure that stored fields loaded from a certain thread are not read from a different thread.We have not hit this before because the problem revolves around
SearchLookupwhich is used by runtime fields.TopHitsITis the main test we have for top hits agg, but it uses a mock script engine which bypasses painless andSearchLookup.