[JackieTien97]

Summary

• preserve fragment failure information before concurrent cancellation removes the fragment context
• apply the fix to both data and schema fragment execution paths
• add deterministic regression tests for the cancellation/planning-failure race

Root cause

cancelTask removes the FragmentInstanceContext before waiting for the in-progress instanceExecution.computeIfAbsent call. If planning then fails, the failure path returns from computeIfAbsent and looks the context up again. The lookup can return null, causing an NPE that masks the original failure, such as metadata lease fencing status 536.

Impact

The original fragment failure and status are returned instead of an unrelated NPE.

Validation

• mvn compile -pl iotdb-core/datanode -am -DskipTests
• mvn test -pl iotdb-core/datanode -am -Dtest=FragmentInstanceManagerTest -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false (2 tests passed)