From 83032572972360c057369fdea4792a363fbd185b Mon Sep 17 00:00:00 2001
From: Dmitry Konstantinov <netudima@gmail.com>
Date: Wed, 18 Feb 2026 11:39:05 +0000
Subject: [PATCH] Improve diagnostics for JUnit tests which crashed or timed
 out on Jenkins

Add test container memory events printing to check if Linux OOM killer was active
Fix thread dump printing on junit test timeout
Process.pid() API is available since JDK9

patch by Dmitry Konstantinov; reviewed by Michael Semb Wever for CASSANDRA-21172
---
 .jenkins/Jenkinsfile                          |  5 ++++
 .../org/apache/cassandra/JStackJUnitTask.java | 23 +++++++------------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/.jenkins/Jenkinsfile b/.jenkins/Jenkinsfile
index 4aa1dcd44a..faf3f410cf 100644
--- a/.jenkins/Jenkinsfile
+++ b/.jenkins/Jenkinsfile
@@ -433,6 +433,11 @@ def test(command, cell) {
             if (!cell.step.startsWith("microbench")) {
               junit testResults: "test/**/TEST-*.xml,test/**/cqlshlib*.xml,test/**/nosetests*.xml", testDataPublishers: [[$class: 'StabilityTestDataPublisher']]
             }
+            // check if we had Linux OOM killer active within the test container which could kill forked JUnit JVM processes
+             sh """
+                echo "docker memory/oomkiller debug:"
+                cat /sys/fs/cgroup/docker/memory.events || true
+              """
             sh """
                 find test/output -type f -name "*.xml" -print0 | xargs -0 -r -n1 -P"\$(nproc)" xz -f
                 echo "test result files compressed"; find test/output -type f -name "*.xml.xz" | wc -l
diff --git a/test/unit/org/apache/cassandra/JStackJUnitTask.java b/test/unit/org/apache/cassandra/JStackJUnitTask.java
index 69480a6a47..334525992b 100644
--- a/test/unit/org/apache/cassandra/JStackJUnitTask.java
+++ b/test/unit/org/apache/cassandra/JStackJUnitTask.java
@@ -20,7 +20,6 @@ package org.apache.cassandra;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
-import java.lang.reflect.Field;
 
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.taskdefs.ExecuteWatchdog;
@@ -77,6 +76,7 @@ public class JStackJUnitTask extends JUnitTask
                 ProcessBuilder pb = new ProcessBuilder("jstack","-l", String.valueOf(pid));
                 try
                 {
+                    pb.redirectErrorStream(true);
                     Process p = pb.start();
                     try (BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream())))
                     {
@@ -100,22 +100,15 @@ public class JStackJUnitTask extends JUnitTask
 
         private long getPid(Process process)
         {
-            if (process.getClass().getName().equals("java.lang.UNIXProcess"))
+            try
             {
-                try
-                {
-                    Field f = process.getClass().getDeclaredField("pid");
-                    f.setAccessible(true);
-                    long pid = f.getLong(process);
-                    f.setAccessible(false);
-                    return pid;
-                }
-                catch (IllegalAccessException | NoSuchFieldException e)
-                {
-                    System.err.println("Could not get PID");
-                }
+                return process.pid();
+            }
+            catch (UnsupportedOperationException e)
+            {
+                System.err.println("Could not get PID");
+                return -1;
             }
-            return -1;
         }
     }