Efficient and stable quorum-based log replication and replay for modern cluster-databases
Efficient and stable quorum-based log replication and replay for modern cluster-databases
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DOI：
10.1007/s11704-020-0210-y
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发表时间：
2022-01
影响因子：
4.2
通讯作者：
Donghui Wang;Peng Cai;Weining Qian;Aoying Zhou
中科院分区：
文献类型：
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作者：
Donghui Wang;Peng Cai;Weining Qian;Aoying Zhou
现代内存数据库（IMDB）可以支持高度并发的联机事务处理（OLTP）工作负载，并每秒生成大量事务日志。Paxos、Raft等基于仲裁的复制协议在分布式数据库中得到了广泛的应用，以提供更高的可用性和容错性。然而，复制IMDB并不简单，因为高事务速率带来了新的挑战。首先，在仲裁复制中的领导者节点应具有自适应性，通过考虑不同的事务到达率和追随者节点的处理能力。第二，在高并发环境下，要求follower重放日志以赶上leader的状态，以减少可见性差距。第三，现代数据库往往是由低配置网络连接的商品机器集群组成的，其中经常发生网络异常。在这种情况下，性能将受到显著影响，因为跟随节点福尔斯落入长持续时间异常处理过程（例如，从领队处取回丢失的日志）。为此，我们建立了QuorumX，一个高效和稳定的基于仲裁的复制框架IMDB在沉重的OLTP工作负载。QuorumX结合了基于关键路径的并行计算和流水线并行计算，提供了一个自适应的日志传播方案，以在各种设置下获得稳定和高性能。此外，我们提出了一个安全的和无协调的日志重放方案，以尽量减少领导者和追随者IMDB之间的可见性差距。为了减轻网络不可靠性对复制性能的影响，我们进一步对跟随节点进行了细致的设计。我们的评估结果与YCSB，TPC-C和一个现实的微基准测试表明，QuorumX实现了性能接近异步主备份复制，并始终可以提供一个稳定的服务，数据一致性和低级别的可见性差距。
The modern in-memory database (IMDB) can support highly concurrent on-line transaction processing (OLTP) workloads and generate massive transactional logs per second. Quorum-based replication protocols such as Paxos or Raft have been widely used in the distributed databases to offer higher availability and fault-tolerance. However, it is non-trivial to replicate IMDB because high transaction rate has brought new challenges. First, the leader node in quorum replication should have adaptivity by considering various transaction arrival rates and the processing capability of follower nodes. Second, followers are required to replay logs to catch up the state of the leader in the highly concurrent setting to reduce visibility gap. Third, modern databases are often built with a cluster of commodity machines connected by low configuration networks, in which the network anomalies often happen. In this case, the performance would be significantly affected because the follower node falls into the long-duration exception handling process (e.g., fetch lost logs from the leader). To this end, we build QuorumX, an efficient and stable quorum-based replication framework for IMDB under heavy OLTP workloads. QuorumX combines critical path based batching and pipeline batching to provide an adaptive log propagation scheme to obtain a stable and high performance at various settings. Further, we propose a safe and coordination-free log replay scheme to minimize the visibility gap between the leader and follower IMDBs. We further carefully design the process for the follower node in order to alleviate the influence of the unreliable network on the replication performance. Our evaluation results with the YCSB, TPC-C and a realistic microbenchmark demonstrate that QuorumX achieves the performance close to asynchronous primary-backup replication and could always provide a stable service with data consistency and a low-level visibility gap.