Print thread dumps when PR build is cancelled

Closes gh-35760

.github/actions/print-jvm-thread-dumps/action.yml

@@ -0,0 +1,14 @@
+name: Print JVM thread dumps
+description: Prints a thread dump for all running JVMs
+runs:
+  using: composite
+  steps:
+    - run: |
+        for java_pid in $(jps -q -J-XX:+PerfDisableSharedMem); do
+          echo "------------------------ pid $java_pid ------------------------"
+          cat /proc/$java_pid/cmdline | xargs -0 echo
+          jcmd $java_pid Thread.print -l
+          jcmd $java_pid GC.heap_info
+        done
+        exit 0
+      shell: bash

.github/workflows/build-pull-request.yml

@@ -30,3 +30,7 @@ jobs:
           CI: 'true'
           GRADLE_ENTERPRISE_URL: 'https://ge.spring.io'
         run: ./gradlew -Dorg.gradle.internal.launcher.welcomeMessageEnabled=false --no-daemon --max-workers=4 --continue build
+
+      - name: Print JVM thread dumps when cancelled
+        uses: ./.github/actions/print-jvm-thread-dumps
+        if: cancelled()