From da725818f0d5039d0ca513b6a3a20ac101f45ae5 Mon Sep 17 00:00:00 2001
From: Gregorius Soedharmo <arkatufus@yahoo.com>
Date: Thu, 2 Jun 2022 01:16:42 +0700
Subject: [PATCH] Backport #5976 - Fix sharding tolerant reader

---
 .../Akka.Cluster.Sharding/PersistentShardCoordinator.cs    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/contrib/cluster/Akka.Cluster.Sharding/PersistentShardCoordinator.cs b/src/contrib/cluster/Akka.Cluster.Sharding/PersistentShardCoordinator.cs
index 3b3fc5cf843..851b633ee63 100644
--- a/src/contrib/cluster/Akka.Cluster.Sharding/PersistentShardCoordinator.cs
+++ b/src/contrib/cluster/Akka.Cluster.Sharding/PersistentShardCoordinator.cs
@@ -109,7 +109,12 @@ protected override bool ReceiveRecover(object message)
                             if (State.RegionProxies.Contains(proxyTerminated.RegionProxy))
                                 State = State.Updated(evt);
                             return true;
-                        case ShardHomeAllocated _:
+                        case ShardHomeAllocated homeAllocated:
+                            // if we already have identical ShardHomeAllocated data, skip processing it
+                            // addresses https://github.com/akkadotnet/akka.net/issues/5604
+                            if (State.Shards.TryGetValue(homeAllocated.Shard, out var currentShardRegion)
+                                && Equals(homeAllocated.Region, currentShardRegion))
+                                return true;
                             State = State.Updated(evt);
                             return true;
                         case ShardHomeDeallocated _: