From aba54e8af84bd3353fa58a3d53b977908e527fa1 Mon Sep 17 00:00:00 2001
From: Ignacio Vera <ignacio.vera@elastic.co>
Date: Mon, 17 Mar 2025 15:59:08 +0100
Subject: [PATCH] Don't generate stacktrace in TaskCancelledException (#125002)

---
 docs/changelog/125002.yaml                                 | 5 +++++
 .../aggregations/bucket/SearchCancellationIT.java          | 7 ++++---
 .../org/elasticsearch/tasks/TaskCancelledException.java    | 5 +++++
 3 files changed, 14 insertions(+), 3 deletions(-)
 create mode 100644 docs/changelog/125002.yaml

diff --git a/docs/changelog/125002.yaml b/docs/changelog/125002.yaml
new file mode 100644
index 000000000000..6b811cc80f51
--- /dev/null
+++ b/docs/changelog/125002.yaml
@@ -0,0 +1,5 @@
+pr: 125002
+summary: Don't generate stacktrace in `TaskCancelledException`
+area: Search
+type: bug
+issues: []
diff --git a/modules/aggregations/src/internalClusterTest/java/org/elasticsearch/aggregations/bucket/SearchCancellationIT.java b/modules/aggregations/src/internalClusterTest/java/org/elasticsearch/aggregations/bucket/SearchCancellationIT.java
index d225ccc9d173..a1119c64c577 100644
--- a/modules/aggregations/src/internalClusterTest/java/org/elasticsearch/aggregations/bucket/SearchCancellationIT.java
+++ b/modules/aggregations/src/internalClusterTest/java/org/elasticsearch/aggregations/bucket/SearchCancellationIT.java
@@ -43,6 +43,7 @@ import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcke
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailures;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.not;
 
 public class SearchCancellationIT extends AbstractSearchCancellationTestCase {
 
@@ -97,9 +98,7 @@ public class SearchCancellationIT extends AbstractSearchCancellationTestCase {
         }
 
         logger.info("Executing search");
-        // we have to explicitly set error_trace=true for the later exception check for `TimeSeriesIndexSearcher`
         Client client = client();
-        client.threadPool().getThreadContext().putHeader("error_trace", "true");
         TimeSeriesAggregationBuilder timeSeriesAggregationBuilder = new TimeSeriesAggregationBuilder("test_agg");
         ActionFuture<SearchResponse> searchResponse = client.prepareSearch("test")
             .setQuery(matchAllQuery())
@@ -129,7 +128,9 @@ public class SearchCancellationIT extends AbstractSearchCancellationTestCase {
         logger.info("All shards failed with", ex);
         if (lowLevelCancellation) {
             // Ensure that we cancelled in TimeSeriesIndexSearcher and not in reduce phase
-            assertThat(ExceptionsHelper.stackTrace(ex), containsString("TimeSeriesIndexSearcher"));
+            assertThat(ExceptionsHelper.stackTrace(ex), not(containsString("not building sub-aggregations due to task cancellation")));
+        } else {
+            assertThat(ExceptionsHelper.stackTrace(ex), containsString("not building sub-aggregations due to task cancellation"));
         }
     }
 }
diff --git a/server/src/main/java/org/elasticsearch/tasks/TaskCancelledException.java b/server/src/main/java/org/elasticsearch/tasks/TaskCancelledException.java
index 81c7bec678b3..4a56e96aa3f3 100644
--- a/server/src/main/java/org/elasticsearch/tasks/TaskCancelledException.java
+++ b/server/src/main/java/org/elasticsearch/tasks/TaskCancelledException.java
@@ -27,6 +27,11 @@ public class TaskCancelledException extends ElasticsearchException {
         super(in);
     }
 
+    @Override
+    public Throwable fillInStackTrace() {
+        return this;  // this exception doesn't imply a bug, no need for a stack trace
+    }
+
     @Override
     public RestStatus status() {
         // Tasks are typically cancelled at the request of the client, so a 4xx status code is more accurate than the default of 500 (and