From 7a495112dbd2db2ce3d1d4546b847c8f2c880092 Mon Sep 17 00:00:00 2001
From: Bulat Gayazov <bylatgr@gmail.com>
Date: Mon, 29 Sep 2025 17:14:59 +0000
Subject: [PATCH 1/2] Optimized serialization in discovery cache cron job

---
 ydb/core/discovery/discovery.cpp | 14 ++++++++++++--
 ydb/core/discovery/discovery.h   |  2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/ydb/core/discovery/discovery.cpp b/ydb/core/discovery/discovery.cpp
index c9f024146ad2..a84aed081f9b 100644
--- a/ydb/core/discovery/discovery.cpp
+++ b/ydb/core/discovery/discovery.cpp
@@ -238,8 +238,11 @@ namespace NDiscoveryPrivate {
 
     class TDiscoveryCache: public TActorBootstrapped<TDiscoveryCache> {
         THashMap<TString, std::shared_ptr<NDiscovery::TCachedMessageData>> CurrentCachedMessages;
+        THashMap<TString, std::shared_ptr<NDiscovery::TCachedMessageData>> DirtyCachedMessages;
+
         THashMap<TString, std::shared_ptr<NDiscovery::TCachedMessageData>> OldCachedMessages; // when subscriptions are disabled
         THashMap<TString, std::shared_ptr<NDiscovery::TCachedMessageData>> CachedNotAvailable; // for subscriptions
+
         THolder<TEvInterconnect::TEvNodeInfo> NameserviceResponse;
 
         struct TWaiter {
@@ -311,7 +314,10 @@ namespace NDiscoveryPrivate {
 
             Y_ABORT_UNLESS(currentCachedMessage);
 
-            currentCachedMessage->UpdateEntries(std::move(msg->Updates));
+            if (!msg->Updates.empty()) {
+                currentCachedMessage->UpdateEntries(std::move(msg->Updates));
+                DirtyCachedMessages[path] = currentCachedMessage;
+            }
 
             auto it = Requested.find(path);
             Y_ABORT_UNLESS(it == Requested.end());
@@ -336,6 +342,8 @@ namespace NDiscoveryPrivate {
                 EndpointId.GetOrElse({}), {}, msg->Status)
             );
 
+            DirtyCachedMessages.erase(path);
+
             if (AppData()->FeatureFlags.GetEnableSubscriptionsInDiscovery()) {
                 if (msg->Status != TEvStateStorage::TEvBoardInfo::EStatus::Ok) {
                     CurrentCachedMessages.erase(path);
@@ -369,10 +377,12 @@ namespace NDiscoveryPrivate {
 
             Y_ABORT_UNLESS(NameserviceResponse);
 
-            for (auto& [_, cachedData] : CurrentCachedMessages) {
+            for (auto& [_, cachedData] : DirtyCachedMessages) {
                 cachedData->UpdateCache(NameserviceResponse, EndpointId.GetOrElse({}));
             }
 
+            DirtyCachedMessages.clear();
+
             Schedule(TDuration::Seconds(1), new TEvents::TEvWakeup());
         }
 
diff --git a/ydb/core/discovery/discovery.h b/ydb/core/discovery/discovery.h
index 6c96564e7b2b..0e188cce3345 100644
--- a/ydb/core/discovery/discovery.h
+++ b/ydb/core/discovery/discovery.h
@@ -56,6 +56,8 @@ class TCachedMessageData {
     TMap<TActorId, TEvStateStorage::TBoardInfoEntry> InfoEntries; // OwnerId -> Payload
     TEvStateStorage::TEvBoardInfo::EStatus Status;
 
+    bool IsDirty = false;
+
 public:
     TCachedMessageData(const TString& cachedMessage, const TString& cachedMessageSsl,
                         const TMap<TActorId, TEvStateStorage::TBoardInfoEntry>& infoEntries,

From 7d6d7eda41f18840f75cac594c61914dae4397f0 Mon Sep 17 00:00:00 2001
From: Bulat Gayazov <bylatgr@gmail.com>
Date: Mon, 29 Sep 2025 17:29:15 +0000
Subject: [PATCH 2/2] Fix

---
 ydb/core/discovery/discovery.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/ydb/core/discovery/discovery.h b/ydb/core/discovery/discovery.h
index 0e188cce3345..6c96564e7b2b 100644
--- a/ydb/core/discovery/discovery.h
+++ b/ydb/core/discovery/discovery.h
@@ -56,8 +56,6 @@ class TCachedMessageData {
     TMap<TActorId, TEvStateStorage::TBoardInfoEntry> InfoEntries; // OwnerId -> Payload
     TEvStateStorage::TEvBoardInfo::EStatus Status;
 
-    bool IsDirty = false;
-
 public:
     TCachedMessageData(const TString& cachedMessage, const TString& cachedMessageSsl,
                         const TMap<TActorId, TEvStateStorage::TBoardInfoEntry>& infoEntries,