Merge

dbms/include/DB/Storages/StorageReplicatedMergeTree.h

@@ -246,9 +246,10 @@ private:
 
 	/// Поток, выбирающий куски для слияния.
 	std::thread merge_selecting_thread;
+	/// Поток, удаляющий информацию о старых блоках из ZooKeeper.
+	std::thread clear_old_blocks_thread;
 
-	/// Когда последний раз выбрасывали старые данные из ZooKeeper.
+	/// Когда последний раз выбрасывали старые логи из ZooKeeper.
-	time_t clear_old_blocks_time = 0;
 	time_t clear_old_logs_time = 0;
 
 	Logger * log;
@@ -347,6 +348,10 @@ private:
 	  */
 	void mergeSelectingThread();
 
+	/** В бесконечном цикле вызывает clearOldBlocks.
+	  */
+	void clearOldBlocksThread();
+
 	/// Вызывается во время выбора кусков для слияния.
 	bool canMergeParts(const MergeTreeData::DataPartPtr & left, const MergeTreeData::DataPartPtr & right);
 

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -369,10 +369,15 @@ void StorageReplicatedMergeTree::clearOldBlocks()
 	if (!zookeeper.exists(zookeeper_path + "/blocks", &stat))
 		throw Exception(zookeeper_path + "/blocks doesn't exist", ErrorCodes::NOT_FOUND_NODE);
 
+	int children_count = stat.getnumChildren();
+
 	/// Чтобы делать "асимптотически" меньше запросов exists, будем ждать, пока накопятся в 1.1 раза больше блоков, чем нужно.
-	if (static_cast<double>(stat.getnumChildren()) < data.settings.replicated_deduplication_window * 1.1)
+	if (static_cast<double>(children_count) < data.settings.replicated_deduplication_window * 1.1)
 		return;
 
+	LOG_TRACE(log, "Clearing about " << static_cast<size_t>(children_count) - data.settings.replicated_deduplication_window
+		<< " old blocks from ZooKeeper");
+
 	Strings blocks = zookeeper.getChildren(zookeeper_path + "/blocks");
 
 	std::vector<std::pair<Int64, String> > timed_blocks;
@@ -384,10 +389,14 @@ void StorageReplicatedMergeTree::clearOldBlocks()
 		timed_blocks.push_back(std::make_pair(stat.getczxid(), block));
 	}
 
-	std::sort(timed_blocks.begin(), timed_blocks.end());
+	std::sort(timed_blocks.begin(), timed_blocks.end(), std::greater<std::pair<Int64, String>>());
 	for (size_t i = data.settings.replicated_deduplication_window; i <  timed_blocks.size(); ++i)
 	{
-		zookeeper.remove(zookeeper_path + "/blocks/" + timed_blocks[i].second);
+		zkutil::Ops ops;
+		ops.push_back(new zkutil::Op::Remove(zookeeper_path + "/blocks/" + timed_blocks[i].second + "/number", -1));
+		ops.push_back(new zkutil::Op::Remove(zookeeper_path + "/blocks/" + timed_blocks[i].second + "/checksums", -1));
+		ops.push_back(new zkutil::Op::Remove(zookeeper_path + "/blocks/" + timed_blocks[i].second, -1));
+		zookeeper.multi(ops);
 	}
 
 	LOG_TRACE(log, "Cleared " << blocks.size() - data.settings.replicated_deduplication_window << " old blocks from ZooKeeper");
@@ -882,21 +891,38 @@ void StorageReplicatedMergeTree::mergeSelectingThread()
 			tryLogCurrentException(__PRETTY_FUNCTION__);
 		}
 
-		if (shutdown_called)
+		if (shutdown_called || !is_leader_node)
 			break;
 
-		/// Каждую минуту выбрасываем старые блоки.
-		if (time(0) - clear_old_blocks_time > 60)
-		{
-			clear_old_blocks_time = time(0);
-			clearOldBlocks();
-		}
-
 		if (!success)
 			std::this_thread::sleep_for(MERGE_SELECTING_SLEEP);
 	}
 }
 
+void StorageReplicatedMergeTree::clearOldBlocksThread()
+{
+	while (!shutdown_called && is_leader_node)
+	{
+		try
+		{
+			clearOldBlocks();
+		}
+		catch (...)
+		{
+			tryLogCurrentException(__PRETTY_FUNCTION__);
+		}
+
+		/// Спим минуту, но проверяем, нужно ли завершиться, каждую секунду.
+		/// TODO: Лучше во всех подобных местах использовать condition variable.
+		for (size_t i = 0; i < 60; ++i)
+		{
+			if (shutdown_called || !is_leader_node)
+				break;
+			std::this_thread::sleep_for(std::chrono::seconds(1));
+		}
+	}
+}
+
 bool StorageReplicatedMergeTree::canMergeParts(const MergeTreeData::DataPartPtr & left, const MergeTreeData::DataPartPtr & right)
 {
 	if (currently_merging.count(left->name) || currently_merging.count(right->name))
@@ -925,6 +951,7 @@ void StorageReplicatedMergeTree::becomeLeader()
 	LOG_INFO(log, "Became leader");
 	is_leader_node = true;
 	merge_selecting_thread = std::thread(&StorageReplicatedMergeTree::mergeSelectingThread, this);
+	clear_old_blocks_thread = std::thread(&StorageReplicatedMergeTree::clearOldBlocksThread, this);
 }
 
 String StorageReplicatedMergeTree::findReplicaHavingPart(const String & part_name, bool active)
@@ -992,7 +1019,10 @@ void StorageReplicatedMergeTree::shutdown()
 
 	LOG_TRACE(log, "Waiting for threads to finish");
 	if (is_leader_node)
+	{
 		merge_selecting_thread.join();
+		clear_old_blocks_thread.join();
+	}
 	queue_updating_thread.join();
 	for (auto & thread : queue_threads)
 		thread.join();