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Fix missing removal of query cancellation callback in QueryPhase #130279

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Merged
merged 11 commits into from
Jul 24, 2025
Merged

Fix missing removal of query cancellation callback in QueryPhase #130279

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f5a5daa
Fix missing removal of query cancellation callback in QueryPhase
jessepeixoto Jun 28, 2025
cf1d49f
Merge branch 'main' into fix-timeout-callback-removal
piergm Jun 30, 2025
6e4edce
Adds changelog
piergm Jun 30, 2025
5fc5f49
Merge branch 'main' into fix-timeout-callback-removal
jessepeixoto Jul 2, 2025
103a1c1
Merge branch 'main' into fix-timeout-callback-removal
piergm Jul 7, 2025
7314f4d
Only remove query cancellation callback when allowPartialSearchResult…
jessepeixoto Jul 9, 2025
57da03a
Merge branch 'main' into fix-timeout-callback-removal
jessepeixoto Jul 9, 2025
15c3582
Move query cancellations to SearchService
jessepeixoto Jul 13, 2025
0014df9
Clarify and adjust cancellation behavior in single shard fetch phase
jessepeixoto Jul 14, 2025
9bc2874
Test clear query cancellations
jessepeixoto Jul 15, 2025
ae84b60
Merge branch 'main' into fix-timeout-callback-removal
javanna Jul 23, 2025
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5 changes: 5 additions & 0 deletions docs/changelog/130279.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
pr: 130279
summary: Fix missing removal of query cancellation callback in QueryPhase
area: Search
type: bug
issues: [130071]
4 changes: 3 additions & 1 deletion server/src/main/java/org/elasticsearch/search/SearchService.java
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Original file line number Diff line number Diff line change
Expand Up @@ -907,7 +907,9 @@ private SearchPhaseResult executeQueryPhase(ShardSearchRequest request, Cancella
tracer.stopTrace(task);
}
if (request.numberOfShards() == 1 && (request.source() == null || request.source().rankBuilder() == null)) {
// we already have query results, but we can run fetch at the same time
// in this case, we reuse search context across search and fetch phases.
// so we need to remove all cancelation callbacks from query phase before starting fetch.
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could you leave the initial comment, and perhaps rewrite the new part to something like

in this case we reuse the search context across search and fetch phase, hence we need to clear the cancellation checks that were applied by the query phase before running fetch. Note that the timeout checks are not applied to the fetch phase, while the cancellation checks are.

context.searcher().removeQueryCancellations();
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There are two main scenarios where we get into this codepath:

  1. multiple shards: new search context just created, #preProcess was called, the cancellation checks are added
  2. single shard: search context being reused, we need to clean up the timeout check but not the cancellation checks. Alternatively, we can clear it all up and then add back the cancellation check only.

We are good for the first scenario.

I think that in the second case, calling preProcess again may fix it but other cause other side effects. Perhaps we should restore the cancellation check as follows after the removal:

if (context.lowLevelCancellation()) {
    context.searcher().addQueryCancellation(() -> {
        if (task != null) {
            task.ensureNotCancelled();
        }
    });
}

I still prefer this over selectively removing only the timeout check, although it's not super clear. What do you think?

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I like this solution, it addresses the problem in a focused way, and the comment makes it very clear.

context.addFetchResult();
return executeFetchPhase(readerContext, context, afterQueryTime);
} else {
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5 changes: 5 additions & 0 deletions server/src/main/java/org/elasticsearch/search/internal/ContextIndexSearcher.java
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Expand Up @@ -187,6 +187,11 @@ public void close() {
this.cancellable.clear();
}

// remove all registered cancellation callbacks to prevent them from leaking into other phases
public void removeQueryCancellations() {
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I have second thoughts on the naming I picked, sorry! Should we go with clearQueryCancellations ?

this.cancellable.clear();
}

public boolean hasCancellations() {
return this.cancellable.isEnabled();
}
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