From 913fad0af49ebb6d1def877a4995c0cd65387ff5 Mon Sep 17 00:00:00 2001
From: Tom Gabsow <gabsow.tom@gmail.com>
Date: Tue, 20 Oct 2026 13:58:16 +0300
Subject: [PATCH] Retry SAVE when a background save is already in progress

---
 RLTest/redis_std.py          | 17 +++++++++++-
 tests/unit/test_redis_std.py | 54 ++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/RLTest/redis_std.py b/RLTest/redis_std.py
index 43fe99f..ff2b9d0 100644
--- a/RLTest/redis_std.py
+++ b/RLTest/redis_std.py
@@ -19,6 +19,7 @@
 _TERMINATE_TIMEOUT = 30
 _INSTRUMENTED_TERMINATE_TIMEOUT = 300
 _KILL_TIMEOUT = 5
+_SAVE_RETRY_TIMEOUT = 10
 
 
 class StandardEnv(object):
@@ -658,7 +659,21 @@ def dumpAndReload(self, restart=False, shardId=None, timeout_sec=0):
             self.stopEnv()
             self.startEnv()
         else:
-            [con.save() for con in conns]
+            for con in conns:
+                deadline = time.monotonic() + _SAVE_RETRY_TIMEOUT
+                while True:
+                    try:
+                        # A concurrent BGSAVE may hold an older snapshot. We still
+                        # need our own successful SAVE before reloading.
+                        con.save()
+                        break
+                    except redis.ResponseError as err:
+                        if str(err) != 'Background save already in progress':
+                            raise
+                        remaining = deadline - time.monotonic()
+                        if remaining <= 0:
+                            raise
+                        time.sleep(min(0.05, remaining))
             try:
                 # Given we've already saved on the prior step, there is no need to SAVE again on the DEBUG RELOAD
                 [con.execute_command('DEBUG', 'RELOAD', 'NOSAVE') for con in conns]
diff --git a/tests/unit/test_redis_std.py b/tests/unit/test_redis_std.py
index 8a24e8f..f3c305b 100644
--- a/tests/unit/test_redis_std.py
+++ b/tests/unit/test_redis_std.py
@@ -2,6 +2,9 @@
 import shutil
 import tempfile
 from unittest import TestCase
+from unittest.mock import Mock, call, patch
+
+import redis
 
 from RLTest.redis_std import StandardEnv
 from tests.unit.test_common import REDIS_BINARY, TLS_CERT, TLS_KEY, TLS_CACERT
@@ -11,6 +14,57 @@
 tlsCaCertFile = 'fake_ca.crt'
 
 
+class TestDumpAndReload(TestCase):
+    def make_env(self, slave=False):
+        env = StandardEnv.__new__(StandardEnv)
+        env.useSlaves = slave
+        env.getConnection = Mock(return_value=Mock())
+        env.getSlaveConnection = Mock(return_value=Mock())
+        return env
+
+    @patch('RLTest.redis_std.time.sleep')
+    def test_busy_save_retries_on_master_and_replica(self, sleep):
+        env = self.make_env(slave=True)
+        for conn in (env.getConnection(), env.getSlaveConnection()):
+            conn.save.side_effect = [
+                redis.ResponseError('Background save already in progress'), True]
+        env.dumpAndReload()
+        for conn in (env.getConnection(), env.getSlaveConnection()):
+            self.assertEqual(conn.mock_calls, [
+                call.save(), call.save(),
+                call.execute_command('DEBUG', 'RELOAD', 'NOSAVE')])
+        self.assertEqual(sleep.call_count, 2)
+
+    @patch('RLTest.redis_std.time.sleep')
+    @patch('RLTest.redis_std.time.monotonic', side_effect=[0, 10])
+    def test_busy_save_timeout_does_not_reload(self, monotonic, sleep):
+        env = self.make_env()
+        conn = env.getConnection()
+        error = redis.ResponseError('Background save already in progress')
+        conn.save.side_effect = error
+        with self.assertRaises(redis.ResponseError) as raised:
+            env.dumpAndReload()
+        self.assertIs(raised.exception, error)
+        conn.save.assert_called_once_with()
+        conn.execute_command.assert_not_called()
+        sleep.assert_not_called()
+
+    @patch('RLTest.redis_std.time.sleep')
+    def test_other_save_errors_are_not_retried(self, sleep):
+        for error in (redis.ResponseError('Permission denied'),
+                      redis.ConnectionError('Connection lost')):
+            with self.subTest(error=error):
+                env = self.make_env()
+                conn = env.getConnection()
+                conn.save.side_effect = error
+                with self.assertRaises(type(error)) as raised:
+                    env.dumpAndReload()
+                self.assertIs(raised.exception, error)
+                conn.save.assert_called_once_with()
+                conn.execute_command.assert_not_called()
+        sleep.assert_not_called()
+
+
 class TestStandardEnv(TestCase):
 
     def setUp(self):