Add a fail point that can hold PS snapshot for five minute.

dbms/src/Common/FailPoint.cpp

@@ -79,7 +79,8 @@ std::unordered_map<String, std::shared_ptr<FailPointChannel>> FailPointHelper::f
     M(force_set_dtfile_exist_when_acquire_id)                \
     M(force_no_local_region_for_mpp_task)                    \
     M(force_remote_read_for_batch_cop)                       \
-    M(force_context_path)
+    M(force_context_path)                                    \
+    M(force_slow_page_storage_snapshot_release)
 
 #define APPLY_FOR_FAILPOINTS_ONCE_WITH_CHANNEL(M) \
     M(pause_after_learner_read)                   \

dbms/src/Storages/DeltaMerge/DeltaMergeStore.cpp

@@ -94,6 +94,7 @@ extern const char force_triggle_foreground_flush[];
 extern const char force_set_segment_ingest_packs_fail[];
 extern const char segment_merge_after_ingest_packs[];
 extern const char random_exception_after_dt_write_done[];
+extern const char force_slow_page_storage_snapshot_release[];
 } // namespace FailPoints
 
 namespace DM
@@ -1036,11 +1037,20 @@ BlockInputStreams DeltaMergeStore::readRaw(const Context & db_context,
                 auto segment_snap = segment->createSnapshot(*dm_context, false, CurrentMetrics::DT_SnapshotOfReadRaw);
                 if (unlikely(!segment_snap))
                     throw Exception("Failed to get segment snap", ErrorCodes::LOGICAL_ERROR);
+
                 tasks.push_back(std::make_shared<SegmentReadTask>(segment, segment_snap, RowKeyRanges{segment->getRowKeyRange()}));
             }
         }
     }
 
+    fiu_do_on(FailPoints::force_slow_page_storage_snapshot_release, {
+        std::thread thread_hold_snapshots([tasks]() {
+            std::this_thread::sleep_for(std::chrono::seconds(5 * 60));
+            (void)tasks;
+        });
+        thread_hold_snapshots.detach();
+    });
+
     auto after_segment_read = [&](const DMContextPtr & dm_context_, const SegmentPtr & segment_) {
         this->checkSegmentUpdate(dm_context_, segment_, ThreadType::Read);
     };

dbms/src/Storages/Page/V3/BlobStore.cpp

@@ -978,6 +978,7 @@ void BlobStore::BlobStats::restore()
 
     for (auto & [path, stats] : stats_map)
     {
+        (void)path;
         for (const auto & stat : stats)
         {
             stat->recalculateSpaceMap();