From 6dad6600393f99c3d413dffefa1bf7f6ee12b79c Mon Sep 17 00:00:00 2001
From: bryn <bryncooke@gmail.com>
Date: Mon, 8 Jun 2020 11:02:42 +0100
Subject: [PATCH] CASSANDRA-15677 Add shutdown to JMX thread pool to avoid
 metaspace errors associated with thread leaks. There are still other thread
 shutdown issues remaining, but this seems to be the most serious one.

---
 .../utils/progress/jmx/JMXBroadcastExecutor.java     |  6 ++++--
 .../cassandra/distributed/impl/AbstractCluster.java  | 12 ++++++++++++
 .../apache/cassandra/distributed/impl/Instance.java  |  4 ++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/java/org/apache/cassandra/utils/progress/jmx/JMXBroadcastExecutor.java b/src/java/org/apache/cassandra/utils/progress/jmx/JMXBroadcastExecutor.java
index f545f0f926..f28609cc6c 100644
--- a/src/java/org/apache/cassandra/utils/progress/jmx/JMXBroadcastExecutor.java
+++ b/src/java/org/apache/cassandra/utils/progress/jmx/JMXBroadcastExecutor.java
@@ -18,9 +18,11 @@
 
 package org.apache.cassandra.utils.progress.jmx;
 
-import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
+import org.apache.cassandra.concurrent.NamedThreadFactory;
+
 /**
  * Holds dedicated executor for JMX event handling. Events will internally queued by ArrayNotificationBuffer,
  * synchronized by an exclusive write lock, which makes a shared single thread executor desirable.
@@ -30,6 +32,6 @@ public final class JMXBroadcastExecutor
 
     private JMXBroadcastExecutor() { }
 
-    public final static Executor executor = Executors.newSingleThreadExecutor();
+    public final static ExecutorService executor = Executors.newSingleThreadExecutor(new NamedThreadFactory("JMX"));
 
 }
diff --git a/test/distributed/org/apache/cassandra/distributed/impl/AbstractCluster.java b/test/distributed/org/apache/cassandra/distributed/impl/AbstractCluster.java
index a164e3b02f..0c8421a94d 100644
--- a/test/distributed/org/apache/cassandra/distributed/impl/AbstractCluster.java
+++ b/test/distributed/org/apache/cassandra/distributed/impl/AbstractCluster.java
@@ -667,9 +667,21 @@ public abstract class AbstractCluster<I extends IInstance> implements ICluster<I
         Thread.setDefaultUncaughtExceptionHandler(previousHandler);
         previousHandler = null;
 
+        //checkForThreadLeaks();
         //withThreadLeakCheck(futures);
     }
 
+    private void checkForThreadLeaks()
+    {
+        //This is an alternate version of the thread leak check that just checks to see if any threads are still alive
+        // with the context classloader.
+        Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
+        threadSet.stream().filter(t->t.getContextClassLoader() instanceof InstanceClassLoader).forEach(t->{
+            t.setContextClassLoader(null);
+            throw new RuntimeException("Unterminated thread detected " + t.getName() + " in group " + t.getThreadGroup().getName());
+        });
+    }
+
     // We do not want this check to run every time until we fix problems with tread stops
     private void withThreadLeakCheck(List<Future<?>> futures)
     {
diff --git a/test/distributed/org/apache/cassandra/distributed/impl/Instance.java b/test/distributed/org/apache/cassandra/distributed/impl/Instance.java
index c3e9982e3e..989bf6e7db 100644
--- a/test/distributed/org/apache/cassandra/distributed/impl/Instance.java
+++ b/test/distributed/org/apache/cassandra/distributed/impl/Instance.java
@@ -108,6 +108,7 @@ import org.apache.cassandra.utils.JVMStabilityInspector;
 import org.apache.cassandra.utils.Throwables;
 import org.apache.cassandra.utils.concurrent.Ref;
 import org.apache.cassandra.utils.memory.BufferPool;
+import org.apache.cassandra.utils.progress.jmx.JMXBroadcastExecutor;
 
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static org.apache.cassandra.distributed.api.Feature.GOSSIP;
@@ -566,6 +567,9 @@ public class Instance extends IsolatedExecutor implements IInvokableInstance
                                 () -> Stage.shutdownAndWait(1L, MINUTES),
                                 () -> SharedExecutorPool.SHARED.shutdownAndWait(1L, MINUTES)
             );
+            error = parallelRun(error, executor,
+                                () -> shutdownAndWait(Collections.singletonList(JMXBroadcastExecutor.executor))
+            );
 
             Throwables.maybeFail(error);
         }).apply(isolatedExecutor);