From 2549eace09f5926e5948fd6b8414a5d156061ce3 Mon Sep 17 00:00:00 2001
From: Rob Bygrave <robin.bygrave@gmail.com>
Date: Fri, 8 Oct 2021 11:20:54 +1300
Subject: [PATCH] #2406 - Memory leak in Query.findEach

---
 .../server/core/OrmQueryRequest.java          |  8 -----
 .../io/ebeaninternal/server/query/CQuery.java |  1 -
 .../tests/basic/TestPersistenceContext.java   | 36 +++++++++++++++++++
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/core/OrmQueryRequest.java b/ebean-core/src/main/java/io/ebeaninternal/server/core/OrmQueryRequest.java
index 4335b56d5..85d89ffe2 100644
--- a/ebean-core/src/main/java/io/ebeaninternal/server/core/OrmQueryRequest.java
+++ b/ebean-core/src/main/java/io/ebeaninternal/server/core/OrmQueryRequest.java
@@ -201,14 +201,6 @@ public final class OrmQueryRequest<T> extends BeanRequest implements SpiOrmQuery
     return persistenceContext;
   }
 
-  /**
-   * Add the bean to the persistence context.
-   */
-  public void persistenceContextAdd(EntityBean bean) {
-    Object id = beanDescriptor.getId(bean);
-    beanDescriptor.contextPut(persistenceContext, id, bean);
-  }
-
   /**
    * This will create a local (readOnly) transaction if no current transaction
    * exists.
diff --git a/ebean-core/src/main/java/io/ebeaninternal/server/query/CQuery.java b/ebean-core/src/main/java/io/ebeaninternal/server/query/CQuery.java
index a865275c6..45a5b5a11 100644
--- a/ebean-core/src/main/java/io/ebeaninternal/server/query/CQuery.java
+++ b/ebean-core/src/main/java/io/ebeaninternal/server/query/CQuery.java
@@ -416,7 +416,6 @@ public final class CQuery<T> implements DbReadContext, CancelableQuery, SpiProfi
     } else {
       // nextBean set to previously read currentBean
       nextBean = currentBean;
-      request.persistenceContextAdd(nextBean);
       // check the current row we have just moved to
       if (checkForDifferentBean()) {
         return true;
diff --git a/ebean-test/src/test/java/org/tests/basic/TestPersistenceContext.java b/ebean-test/src/test/java/org/tests/basic/TestPersistenceContext.java
index e18c55c57..ea894091a 100644
--- a/ebean-test/src/test/java/org/tests/basic/TestPersistenceContext.java
+++ b/ebean-test/src/test/java/org/tests/basic/TestPersistenceContext.java
@@ -2,11 +2,15 @@ package org.tests.basic;
 
 import io.ebean.BaseTestCase;
 import io.ebean.DB;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.tests.model.basic.Customer;
 import org.tests.model.basic.Order;
 import org.tests.model.basic.ResetBasicData;
 
+import java.util.WeakHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -78,4 +82,36 @@ public class TestPersistenceContext extends BaseTestCase {
     }
   }
 
+  @Disabled
+  @Test
+  void findWithGcTest() {
+    for (int j = 0; j < 20; j++) {
+      for (int i = 0; i < 500; i++) {
+        Customer c = new Customer();
+        c.setName("Customer #" + i);
+        DB.save(c);
+      }
+      int customerCount = DB.find(Customer.class).findCount();
+      AtomicInteger count = new AtomicInteger(customerCount);
+
+      WeakHashMap<Customer, Integer> customers = new WeakHashMap<>();
+
+      DB.find(Customer.class).fetch("orders").findEach(customer -> {
+        customers.put(customer, customer.getId());
+        if (count.decrementAndGet() == 0) {
+          // Trigger garbage collection on last iteration and check if beans disappear from memory
+          System.gc();
+          try {
+            Thread.sleep(100);
+          } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            e.printStackTrace();
+          }
+          customers.size(); // expunge stale entries
+          System.out.println("Total instances: " + customerCount + ", instances left in memory: " + customers.size());
+        }
+      });
+    }
+
+  }
 }