From 26afb84415e43548fd10637546165178b4c09d19 Mon Sep 17 00:00:00 2001
From: Wai Lee Chin Feman <wchinfeman@cedar.com>
Date: Tue, 23 Jul 2024 13:10:00 -0400
Subject: [PATCH 1/4] Demo the deadlock

---
 tests/test_bulk_update_models.py | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/tests/test_bulk_update_models.py b/tests/test_bulk_update_models.py
index 9c980ba..608b80a 100644
--- a/tests/test_bulk_update_models.py
+++ b/tests/test_bulk_update_models.py
@@ -1,21 +1,34 @@
 from datetime import datetime, timezone
 
-from django.test import TestCase
+from django.test import TestCase, TransactionTestCase
 from django_bulk_load import bulk_update_models, generate_greater_than_condition
 from .test_project.models import (
     TestComplexModel,
     TestForeignKeyModel,
 )
+import random
+import threading
 
+def do_update():
+    objects = [x for x in TestComplexModel.objects.all()]
+    for current in objects:
+        current.integer_field = random.randint(10,100000)
+    bulk_update_models(objects)
 
-class E2ETestBulkUpdateModels(TestCase):
+class E2ETestBulkUpdateModels(TransactionTestCase):
     def test_integer_field_change(self):
-        model1 = TestComplexModel(integer_field=1)
-        model1.save()
-        model1.integer_field = 2
-        bulk_update_models([model1])
-        saved_model = TestComplexModel.objects.get()
-        self.assertEqual(saved_model.integer_field, 2)
+        models = [TestComplexModel(integer_field=1) for x in range(10000)]
+        for model in models:
+            model.save()
+        threads = [
+                threading.Thread(target=do_update)
+                for x in range(80)
+                ]
+        for t in threads:
+            t.start()
+        for t in threads:
+            t.join()
+        print("JOINED")
 
     def test_string_field_change(self):
         model1 = TestComplexModel(string_field="hello")

From 45775c6dfaef5e013b71fe361b44f00089a18940 Mon Sep 17 00:00:00 2001
From: Wai Lee Chin Feman <wchinfeman@cedar.com>
Date: Tue, 23 Jul 2024 13:16:54 -0400
Subject: [PATCH 2/4] Hack a fix in, to see if it helps (it does)

---
 django_bulk_load/bulk_load.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/django_bulk_load/bulk_load.py b/django_bulk_load/bulk_load.py
index 296b34d..9ec44e0 100644
--- a/django_bulk_load/bulk_load.py
+++ b/django_bulk_load/bulk_load.py
@@ -301,6 +301,8 @@ def bulk_update_models(
     else:
         queries = [update_query]
 
+    helper = f"select id from {table_name} order by id asc for update"
+    queries = [helper] + queries
     return bulk_load_models_with_queries(
         models=models,
         loading_table_name=loading_table_name,

From f59eddd7d6bedbe9d2bfff7f4dac4f0d0faa05a3 Mon Sep 17 00:00:00 2001
From: Wai Lee Chin Feman <wchinfeman@cedar.com>
Date: Tue, 23 Jul 2024 13:58:28 -0400
Subject: [PATCH 3/4] Clean up test output

---
 tests/test_bulk_update_models.py | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/tests/test_bulk_update_models.py b/tests/test_bulk_update_models.py
index 608b80a..6264833 100644
--- a/tests/test_bulk_update_models.py
+++ b/tests/test_bulk_update_models.py
@@ -2,33 +2,42 @@
 
 from django.test import TestCase, TransactionTestCase
 from django_bulk_load import bulk_update_models, generate_greater_than_condition
+import queue
 from .test_project.models import (
     TestComplexModel,
     TestForeignKeyModel,
 )
 import random
 import threading
+import sys
 
-def do_update():
+def do_update(bucket):
     objects = [x for x in TestComplexModel.objects.all()]
     for current in objects:
         current.integer_field = random.randint(10,100000)
-    bulk_update_models(objects)
+    try:
+        bulk_update_models(objects)
+    except Exception:
+        bucket.put(sys.exc_info())
 
 class E2ETestBulkUpdateModels(TransactionTestCase):
     def test_integer_field_change(self):
         models = [TestComplexModel(integer_field=1) for x in range(10000)]
+        error_bucket = queue.Queue()
+
         for model in models:
             model.save()
         threads = [
-                threading.Thread(target=do_update)
+                threading.Thread(target=do_update, args=[error_bucket])
                 for x in range(80)
                 ]
         for t in threads:
             t.start()
         for t in threads:
             t.join()
-        print("JOINED")
+        while not error_bucket.empty():
+            raise error_bucket.get()[1]
+
 
     def test_string_field_change(self):
         model1 = TestComplexModel(string_field="hello")

From dc8756265ae9c7436d38051ebd8b3bbbf04773e3 Mon Sep 17 00:00:00 2001
From: Wai Lee Chin Feman <wchinfeman@cedar.com>
Date: Tue, 23 Jul 2024 14:02:17 -0400
Subject: [PATCH 4/4] Clean up test output

---
 tests/test_bulk_update_models.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/test_bulk_update_models.py b/tests/test_bulk_update_models.py
index 6264833..07cb4e0 100644
--- a/tests/test_bulk_update_models.py
+++ b/tests/test_bulk_update_models.py
@@ -1,5 +1,6 @@
 from datetime import datetime, timezone
 
+from django.db import close_old_connections
 from django.test import TestCase, TransactionTestCase
 from django_bulk_load import bulk_update_models, generate_greater_than_condition
 import queue
@@ -19,6 +20,7 @@ def do_update(bucket):
         bulk_update_models(objects)
     except Exception:
         bucket.put(sys.exc_info())
+    close_old_connections()
 
 class E2ETestBulkUpdateModels(TransactionTestCase):
     def test_integer_field_change(self):
@@ -29,7 +31,7 @@ def test_integer_field_change(self):
             model.save()
         threads = [
                 threading.Thread(target=do_update, args=[error_bucket])
-                for x in range(80)
+                for x in range(40)
                 ]
         for t in threads:
             t.start()