From c3b2303810acb56fc32bc8a1ec1032056d713e97 Mon Sep 17 00:00:00 2001
From: Paulo Motta <paulo@apache.org>
Date: Fri, 10 Oct 2025 14:56:30 -0400
Subject: [PATCH] Heap dump should not be generated on handled exceptions

Patch by Paulo Motta; Reviewed by Isaac Reath, Stefan Miklosovic for CASSANDRA-20974
---
 CHANGES.txt                                   |  3 ++-
 .../org/apache/cassandra/utils/HeapUtils.java |  4 ----
 .../utils/JVMStabilityInspector.java          | 23 ++++++++++++++-----
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 401ac07a1e..eb95066bbe 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,6 +1,7 @@
 5.0.7
+ * Heap dump should not be generated on handled exceptions (CASSANDRA-20974)
 Merged from 4.1:
-* ReadCommandController should close fast to avoid deadlock when building secondary index (CASSANDRA-19564)
+ * ReadCommandController should close fast to avoid deadlock when building secondary index (CASSANDRA-19564)
 Merged from 4.0:
  * Updated dtest-api to 0.0.18 and removed JMX-related classes that now live in the dtest-api (CASSANDRA-20884)
 
diff --git a/src/java/org/apache/cassandra/utils/HeapUtils.java b/src/java/org/apache/cassandra/utils/HeapUtils.java
index 38a6969908..6171866b40 100644
--- a/src/java/org/apache/cassandra/utils/HeapUtils.java
+++ b/src/java/org/apache/cassandra/utils/HeapUtils.java
@@ -128,10 +128,6 @@ public final class HeapUtils
 
                     return fullPath;
                 }
-                else
-                {
-                    logger.debug("Heap dump creation on uncaught exceptions is disabled.");
-                }
             }
             catch (Throwable e)
             {
diff --git a/src/java/org/apache/cassandra/utils/JVMStabilityInspector.java b/src/java/org/apache/cassandra/utils/JVMStabilityInspector.java
index a396ef9947..c35c7eb938 100644
--- a/src/java/org/apache/cassandra/utils/JVMStabilityInspector.java
+++ b/src/java/org/apache/cassandra/utils/JVMStabilityInspector.java
@@ -75,7 +75,7 @@ public final class JVMStabilityInspector
             if (t2 != t && (t2 instanceof FSError || t2 instanceof CorruptSSTableException))
                 logger.error("Exception in thread {}", thread, t2);
         }
-        JVMStabilityInspector.inspectThrowable(t);
+        inspectThrowable(t, JVMStabilityInspector::inspectDiskError, true);
     }
 
     /**
@@ -86,12 +86,12 @@ public final class JVMStabilityInspector
      */
     public static void inspectThrowable(Throwable t) throws OutOfMemoryError
     {
-        inspectThrowable(t, JVMStabilityInspector::inspectDiskError);
+        inspectThrowable(t, JVMStabilityInspector::inspectDiskError, false);
     }
 
     public static void inspectCommitLogThrowable(Throwable t)
     {
-        inspectThrowable(t, JVMStabilityInspector::inspectCommitLogError);
+        inspectThrowable(t, JVMStabilityInspector::inspectCommitLogError, false);
     }
 
     private static void inspectDiskError(Throwable t)
@@ -102,7 +102,7 @@ public final class JVMStabilityInspector
             FileUtils.handleFSError((FSError) t);
     }
 
-    public static void inspectThrowable(Throwable t, Consumer<Throwable> fn) throws OutOfMemoryError
+    public static void inspectThrowable(Throwable t, Consumer<Throwable> fn, boolean isUncaughtException) throws OutOfMemoryError
     {
         boolean isUnstable = false;
         if (t instanceof OutOfMemoryError)
@@ -136,7 +136,18 @@ public final class JVMStabilityInspector
         }
 
         // Anything other than an OOM, we should try and heap dump to capture what's going on if configured to do so
-        HeapUtils.maybeCreateHeapDump();
+        if (isUncaughtException && DatabaseDescriptor.getDumpHeapOnUncaughtException())
+        {
+            try
+            {
+                // Avoid entering maybeCreateHeapDump unless the setting is enabled to avoid expensive lock
+                HeapUtils.maybeCreateHeapDump();
+            }
+            catch (Throwable sub)
+            {
+                t.addSuppressed(sub);
+            }
+        }
 
         if (t instanceof InterruptedException)
             throw new UncheckedInterruptedException((InterruptedException) t);
@@ -167,7 +178,7 @@ public final class JVMStabilityInspector
         }
 
         if (t.getCause() != null)
-            inspectThrowable(t.getCause(), fn);
+            inspectThrowable(t.getCause(), fn, isUncaughtException);
     }
 
     private static final Set<String> FORCE_HEAP_OOM_IGNORE_SET = ImmutableSet.of("Java heap space", "GC Overhead limit exceeded");