Blocking clients should not crash if an active replica loads a remote RDB with a key in the blocklist

Former-commit-id: 1c525e20b10e0a47af687a0d46faf75229a1cbf5

src/blocked.cpp

@@ -672,6 +672,13 @@ void signalKeyAsReady(redisDb *db, robj *key) {
     /* Key was already signaled? No need to queue it again. */
     if (dictFind(db->ready_keys,key) != NULL) return;
 
+    if (key->getrefcount() == OBJ_STATIC_REFCOUNT) {
+        // Sometimes a key may be stack allocated, we'll need to dupe it
+        robj *newKey = createStringObject(szFromObj(key), sdslen(szFromObj(key)));
+        newKey->setrefcount(0); // Start with 0 but don't free
+        key = newKey;
+    }
+
     /* Ok, we need to queue this key into g_pserver->ready_keys. */
     rl = (readyList*)zmalloc(sizeof(*rl), MALLOC_SHARED);
     rl->key = key;

src/replication.cpp

@@ -3049,7 +3049,8 @@ struct redisMaster *replicationAddMaster(char *ip, int port) {
         else
             freeClientAsync(mi->master);
     }
-    disconnectAllBlockedClients(); /* Clients blocked in master, now replica. */
+    if (!g_pserver->fActiveReplica)
+        disconnectAllBlockedClients(); /* Clients blocked in master, now replica. */
 
     /* Update oom_score_adj */
     setOOMScoreAdj(-1);

tests/integration/replication-active.tcl

@@ -247,6 +247,23 @@ start_server {tags {"active-repl"} overrides {active-replica yes}} {
         assert_equal {bar} [$master get testkey] {master is correct}
     }
 
+    test {Active replica merge works with client blocked} {
+        $slave flushall
+        $slave replicaof no one
+        $master replicaof no one
+        after 100
+        set rd [redis_deferring_client]
+        $rd blpop testlist 0
+        $slave lpush testlist foo
+        
+        #OK Now reconnect
+        $slave replicaof $master_host $master_port
+        $master replicaof $slave_host $slave_port
+        after 1000
+
+        $rd read
+    } {testlist foo}
+
     test {Active replica different databases} {
         $master select 3
         $master set testkey abcd