Separated pool for background moves

dbms/src/Core/Settings.h

@@ -76,6 +76,7 @@ struct Settings : public SettingsCollection<Settings>
     M(SettingBool, use_uncompressed_cache, true, "Whether to use the cache of uncompressed blocks.", 0) \
     M(SettingBool, replace_running_query, false, "Whether the running request should be canceled with the same id as the new one.", 0) \
     M(SettingUInt64, background_pool_size, 16, "Number of threads performing background work for tables (for example, merging in merge tree). Only has meaning at server startup.", 0) \
+    M(SettingUInt64, background_move_pool_size, 8, "Number of threads performing background moves for tables. Only has meaning at server startup.", 0) \
     M(SettingUInt64, background_schedule_pool_size, 16, "Number of threads performing background tasks for replicated tables. Only has meaning at server startup.", 0) \
     \
     M(SettingMilliseconds, distributed_directory_monitor_sleep_time_ms, 100, "Sleep time for StorageDistributed DirectoryMonitors, in case of any errors delay grows exponentially.", 0) \

dbms/src/Interpreters/Context.cpp

@@ -140,6 +140,7 @@ struct ContextShared
     ConfigurationPtr users_config;                          /// Config with the users, profiles and quotas sections.
     InterserverIOHandler interserver_io_handler;            /// Handler for interserver communication.
     std::optional<BackgroundProcessingPool> background_pool; /// The thread pool for the background work performed by the tables.
+    std::optional<BackgroundProcessingPool> background_move_pool; /// The thread pool for the background moves performed by the tables.
     std::optional<BackgroundSchedulePool> schedule_pool;    /// A thread pool that can run different jobs in background (used in replicated tables)
     MultiVersion<Macros> macros;                            /// Substitutions extracted from config.
     std::unique_ptr<DDLWorker> ddl_worker;                  /// Process ddl commands from zk.
@@ -287,6 +288,7 @@ struct ContextShared
         external_dictionaries_loader.reset();
         external_models_loader.reset();
         background_pool.reset();
+        background_move_pool.reset();
         schedule_pool.reset();
         ddl_worker.reset();
 
@@ -1489,6 +1491,14 @@ BackgroundProcessingPool & Context::getBackgroundPool()
     return *shared->background_pool;
 }
 
+BackgroundProcessingPool & Context::getBackgroundMovePool()
+{
+    auto lock = getLock();
+    if (!shared->background_move_pool)
+        shared->background_move_pool.emplace(settings.background_move_pool_size, "BackgroundMovePool", "BgMoveProcPool");
+    return *shared->background_move_pool;
+}
+
 BackgroundSchedulePool & Context::getSchedulePool()
 {
     auto lock = getLock();

dbms/src/Interpreters/Context.h

@@ -450,6 +450,7 @@ class Context
     void dropCaches() const;
 
     BackgroundProcessingPool & getBackgroundPool();
+    BackgroundProcessingPool & getBackgroundMovePool();
     BackgroundSchedulePool & getSchedulePool();
 
     void setDDLWorker(std::unique_ptr<DDLWorker> ddl_worker);

dbms/src/Storages/MergeTree/BackgroundProcessingPool.cpp

@@ -61,9 +61,12 @@ void BackgroundProcessingPoolTaskInfo::wake()
 }
 
 
-BackgroundProcessingPool::BackgroundProcessingPool(int size_) : size(size_)
+BackgroundProcessingPool::BackgroundProcessingPool(int size_, const char * log_name, const char * thread_name_)
+    : size(size_)
+    , thread_name(thread_name_)
 {
-    LOG_INFO(&Logger::get("BackgroundProcessingPool"), "Create BackgroundProcessingPool with " << size << " threads");
+    logger = &Logger::get(log_name);
+    LOG_INFO(logger, "Create " << log_name << " with " << size << " threads");
 
     threads.resize(size);
     for (auto & thread : threads)
@@ -122,7 +125,7 @@ BackgroundProcessingPool::~BackgroundProcessingPool()
 
 void BackgroundProcessingPool::threadFunction()
 {
-    setThreadName("BackgrProcPool");
+    setThreadName(thread_name);
 
     {
         std::lock_guard lock(tasks_mutex);

dbms/src/Storages/MergeTree/BackgroundProcessingPool.h

@@ -46,7 +46,9 @@ class BackgroundProcessingPool
     using TaskHandle = std::shared_ptr<TaskInfo>;
 
 
-    BackgroundProcessingPool(int size_);
+    BackgroundProcessingPool(int size_,
+        const char * log_name = "BackgroundProcessingPool",
+        const char * thread_name_ = "BackgrProcPool");
 
     size_t getNumberOfThreads() const
     {
@@ -67,6 +69,8 @@ class BackgroundProcessingPool
     using Threads = std::vector<ThreadFromGlobalPool>;
 
     const size_t size;
+    const char * thread_name;
+    Poco::Logger * logger;
 
     Tasks tasks;         /// Ordered in priority.
     std::mutex tasks_mutex;

dbms/src/Storages/MergeTree/MergeTreeData.cpp

@@ -3486,6 +3486,11 @@ bool MergeTreeData::selectPartsAndMove()
     return moveParts(std::move(moving_tagger));
 }
 
+bool MergeTreeData::areBackgroundMovesNeeded() const
+{
+    return storage_policy->getVolumes().size() > 1;
+}
+
 bool MergeTreeData::movePartsToSpace(const DataPartsVector & parts, DiskSpace::SpacePtr space)
 {
     if (parts_mover.moves_blocker.isCancelled())

dbms/src/Storages/MergeTree/MergeTreeData.h

@@ -939,6 +939,8 @@ class MergeTreeData : public IStorage
     /// Selects parts for move and moves them, used in background process
     bool selectPartsAndMove();
 
+    bool areBackgroundMovesNeeded() const;
+
 private:
     /// RAII Wrapper for atomic work with currently moving parts
     /// Acuire them in constructor and remove them in destructor

dbms/src/Storages/StorageMergeTree.cpp

@@ -99,7 +99,8 @@ void StorageMergeTree::startup()
     /// NOTE background task will also do the above cleanups periodically.
     time_after_previous_cleanup.restart();
     merging_mutating_task_handle = global_context.getBackgroundPool().addTask([this] { return mergeMutateTask(); });
-    moving_task_handle = global_context.getBackgroundPool().addTask([this] { return movePartsTask(); });
+    if (areBackgroundMovesNeeded())
+        moving_task_handle = global_context.getBackgroundMovePool().addTask([this] { return movePartsTask(); });
 }
 
 
@@ -115,7 +116,7 @@ void StorageMergeTree::shutdown()
         global_context.getBackgroundPool().removeTask(merging_mutating_task_handle);
 
     if (moving_task_handle)
-        global_context.getBackgroundPool().removeTask(moving_task_handle);
+        global_context.getBackgroundMovePool().removeTask(moving_task_handle);
 }
 
 

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -2878,7 +2878,8 @@ void StorageReplicatedMergeTree::startup()
         data_parts_exchange_endpoint->getId(replica_path), data_parts_exchange_endpoint, global_context.getInterserverIOHandler());
 
     queue_task_handle = global_context.getBackgroundPool().addTask([this] { return queueTask(); });
-    move_parts_task_handle = global_context.getBackgroundPool().addTask([this] { return movePartsTask(); });
+    if (areBackgroundMovesNeeded())
+        move_parts_task_handle = global_context.getBackgroundMovePool().addTask([this] { return movePartsTask(); });
 
     /// In this thread replica will be activated.
     restarting_thread.start();
@@ -2902,7 +2903,7 @@ void StorageReplicatedMergeTree::shutdown()
     queue_task_handle.reset();
 
     if (move_parts_task_handle)
-        global_context.getBackgroundPool().removeTask(move_parts_task_handle);
+        global_context.getBackgroundMovePool().removeTask(move_parts_task_handle);
     move_parts_task_handle.reset();
 
     if (data_parts_exchange_endpoint_holder)