diff --git a/phoenix-core/src/it/java/org/apache/phoenix/rpc/UpdateCacheIT.java b/phoenix-core/src/it/java/org/apache/phoenix/rpc/UpdateCacheIT.java
index 4de3304e6ee..1af5a3b5122 100644
--- a/phoenix-core/src/it/java/org/apache/phoenix/rpc/UpdateCacheIT.java
+++ b/phoenix-core/src/it/java/org/apache/phoenix/rpc/UpdateCacheIT.java
@@ -40,8 +40,8 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+import org.apache.phoenix.end2end.NeedsOwnMiniClusterTest;
 import org.apache.phoenix.end2end.ParallelStatsDisabledIT;
-import org.apache.phoenix.end2end.ParallelStatsDisabledTest;
 import org.apache.phoenix.jdbc.PhoenixDatabaseMetaData;
 import org.apache.phoenix.jdbc.PhoenixEmbeddedDriver;
 import org.apache.phoenix.query.ConnectionQueryServices;
@@ -66,8 +66,24 @@
 /**
  * Verifies the number of RPC calls from {@link MetaDataClient} updateCache() for transactional and
  * non-transactional tables.
+ *
+ * <p>Categorized as {@link NeedsOwnMiniClusterTest} so failsafe runs this class in its own forked
+ * JVM (reuseForks=false). The {@link #helpTestUpdateCache} helper wraps the JVM-singleton
+ * {@link ConnectionQueryServices} returned by {@code driver.getConnectionQueryServices(...)} in a
+ * Mockito spy. Because the Phoenix driver caches that CQS as a process-global singleton and the
+ * spy delegates to the real instance with {@code this} bound to the spy, every internal Phoenix
+ * call back through the services field is recorded in the spy's {@code InvocationContainerImpl},
+ * holding strong references to all arguments. Under the {@code ParallelStatsDisabledTest}
+ * execution ({@code reuseForks=true}) this class previously ran in a fork that had already
+ * accumulated thousands of tests' worth of cached metadata, regions, and live ZK clients on the
+ * same singleton; combined with the spy's invocation-history retention, the fork was tipping over
+ * with {@code OutOfMemoryError: Java heap space} (5.8 GB heap dump from the ZK
+ * {@code main-SendThread}) on {@link #testUpdateCacheForNonTxnTable}. Running in its own JVM
+ * gives the test a fresh CQS singleton with no cross-test accumulation. This follows the same
+ * convention as {@code MetaDataEndPointIT} and other singleton-state-sensitive tests in this
+ * project.
  */
-@Category(ParallelStatsDisabledTest.class)
+@Category(NeedsOwnMiniClusterTest.class)
 public class UpdateCacheIT extends ParallelStatsDisabledIT {
 
   private boolean isLastDDLTimestampValidationEnabled =