diff --git a/cloud/blockstore/libs/discovery/test_server.cpp b/cloud/blockstore/libs/discovery/test_server.cpp
index 0a636d5ccea..689e561b071 100644
--- a/cloud/blockstore/libs/discovery/test_server.cpp
+++ b/cloud/blockstore/libs/discovery/test_server.cpp
@@ -17,6 +17,8 @@
 #include <util/system/mutex.h>
 #include <util/thread/factory.h>
 
+#include <chrono>
+
 namespace NCloud::NBlockStore::NDiscovery {
 
 namespace {
@@ -79,6 +81,7 @@ struct TFakeBlockStoreServer::TImpl
     ui32 LastByteCount = 0;
     bool DropPingRequests = false;
     TVector<std::unique_ptr<TRequestContext>> DroppedRequests;
+    TAtomic ShouldStop = 0;
 
     TImpl(
             ui16 port,
@@ -102,12 +105,19 @@ struct TFakeBlockStoreServer::TImpl
         }
 
         if (Server) {
-            Server->Shutdown();
-            CQ->Shutdown();
-
+            // Need to stop the loop explicitly to avoid possible data race
+            // with grpc server shutdown.
+            // See https://github.com/ydb-platform/nbs/issues/2809
+            AtomicSet(ShouldStop, 1);
             if (Thread) {
                 Thread->Join();
             }
+
+            Server->Shutdown();
+            CQ->Shutdown();
+            // Need to drain completion queue, otherwise it fails on assert when destroying:
+            // https://github.com/ydb-platform/nbs/blob/fbf6b9fa568b7b3861fbccffcf3177ee445f498a/contrib/libs/grpc/src/core/lib/surface/completion_queue.cc#L258
+            DrainCompletionQueue();
         }
     }
 
@@ -153,7 +163,15 @@ struct TFakeBlockStoreServer::TImpl
 
         void* tag;
         bool ok;
-        while (CQ->Next(&tag, &ok)) {
+        while (!AtomicGet(ShouldStop)) {
+            const auto deadline =
+                std::chrono::system_clock::now() +
+                std::chrono::milliseconds(100);
+            auto status = CQ->AsyncNext(&tag, &ok, deadline);
+            if (status != grpc::CompletionQueue::GOT_EVENT) {
+                continue;
+            }
+
             auto* requestContext = static_cast<TRequestContext*>(tag);
 
             if (requestContext->Done || !ok) {
@@ -172,6 +190,21 @@ struct TFakeBlockStoreServer::TImpl
         }
     }
 
+    void DrainCompletionQueue()
+    {
+        void* tag;
+        bool ok;
+        while (CQ->Next(&tag, &ok)) {
+            auto* requestContext = static_cast<TRequestContext*>(tag);
+
+            if (requestContext->Done || !ok) {
+                delete requestContext;
+            } else {
+                FinishRequest(requestContext);
+            }
+        }
+    }
+
     void FinishRequest(TRequestContext* requestContext)
     {
         requestContext->Done = true;