Clean serializers and ThreadLocal fields of VanillaChronicleMap on close()

src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java

@@ -657,15 +657,20 @@ public abstract class VanillaChronicleHash<K,
     @Override
     public final void close() {
         if (resources.releaseManually()) {
-            // Don't try to execute cleaner.clean() and ChronicleHashCloseOnExitHook.remove() from
-            // finally section of try block wrapping resources.releaseManually(), because
-            // Releases nothing after resources.releaseManually(), only removes the cleaner
-            // from the internal linked list of all cleaners.
-            cleaner.clean();
-            ChronicleHashCloseOnExitHook.remove(this);
+            cleanupOnClose();
         }
     }
 
+    protected void cleanupOnClose() {
+        // Releases nothing after resources.releaseManually(), only removes the cleaner
+        // from the internal linked list of all cleaners.
+        cleaner.clean();
+        ChronicleHashCloseOnExitHook.remove(this);
+        // Make GC life easier
+        keyReader = null;
+        keyDataAccess = null;
+    }
+
     @Override
     public boolean isOpen() {
         return !resources.closed();

src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java

@@ -174,6 +174,15 @@ public class VanillaChronicleMap<K, V, R>
         cxt = new ThreadLocal<>();
     }
 
+    @Override
+    protected void cleanupOnClose() {
+        super.cleanupOnClose();
+        // Make GC life easier
+        valueReader = null;
+        valueDataAccess = null;
+        cxt = null;
+    }
+
     public final V checkValue(Object value) {
         if (!valueClass.isInstance(value)) {
             throw new ClassCastException(toIdentityString() + ": Value must be a " +
@@ -297,6 +306,9 @@ public class VanillaChronicleMap<K, V, R>
     }
 
     final ChainingInterface q() {
+        ThreadLocal<ContextHolder> cxt = this.cxt;
+        if (cxt == null)
+            throw new ChronicleHashClosedException(this);
         ContextHolder contextHolder = cxt.get();
         if (contextHolder == null) {
             ChainingInterface queryContext = newQueryContext();
@@ -327,6 +339,9 @@ public class VanillaChronicleMap<K, V, R>
     }
 
     final ChainingInterface i() {
+        ThreadLocal<ContextHolder> cxt = this.cxt;
+        if (cxt == null)
+            throw new ChronicleHashClosedException(this);
         ContextHolder contextHolder = cxt.get();
         if (contextHolder == null) {
             ChainingInterface iterationContext = newIterationContext();

src/test/java/net/openhft/chronicle/map/MemoryLeaksTest.java

@@ -23,7 +23,6 @@ import net.openhft.chronicle.core.OS;
 import net.openhft.chronicle.core.values.IntValue;
 import net.openhft.chronicle.hash.serialization.impl.StringSizedReader;
 import net.openhft.chronicle.hash.serialization.impl.StringUtf8DataAccess;
-import net.openhft.chronicle.map.impl.QueryContextInterface;
 import net.openhft.chronicle.values.Values;
 import org.junit.Assert;
 import org.junit.Before;
@@ -151,21 +150,6 @@ public class MemoryLeaksTest {
         }
         assertEquals(nativeMemoryUsedBeforeMap, nativeMemoryUsed());
         // Wait until chronicle map context (hence serializers) is collected by the GC
-        for (int i = 0; i < 6_000; i++) {
-            if (serializerCount.get() == serializersBeforeMap + 1)
-                break;
-            System.gc();
-            byte[] garbage = new byte[10_000_000];
-            Thread.sleep(10);
-        }
-        Assert.assertEquals(serializersBeforeMap + 1, serializerCount.get());
-        // This assertion ensures GC doesn't reclaim the map before or during the loop iteration
-        // above, to ensure that we test that the direct memory and contexts are released because
-        // of the manual map.close(), despite the "leak" of the map object itself.
-        Assert.assertEquals(0, map.offHeapMemoryUsed());
-        map = null;
-        // After cleaning the reference to the map, the last serializer, which was held in it's
-        // field, should be cleaned as well
         for (int i = 0; i < 6_000; i++) {
             if (serializerCount.get() == serializersBeforeMap)
                 break;
@@ -173,7 +157,11 @@ public class MemoryLeaksTest {
             byte[] garbage = new byte[10_000_000];
             Thread.sleep(10);
         }
-        Assert.assertEquals(serializersBeforeMap, serializerCount.get());
+        Assert.assertTrue(serializerCount.get() == serializersBeforeMap);
+        // This assertion ensures GC doesn't reclaim the map before or during the loop iteration
+        // above, to ensure that we test that the direct memory and contexts are released because
+        // of the manual map.close(), despite the "leak" of the map object itself.
+        Assert.assertEquals(0, map.offHeapMemoryUsed());
     }
 
     private ChronicleMap<IntValue, String> getMap() throws IOException {