MongoDB local.oplog.rs 查询长时间运行

Question

我有 2 个节点集群(8 个 vCPU，52 GB)用于 mongodb(3.2.0)。我正在调试几个需要几秒钟的查询，我运行了 db.currentOp()查看正在运行哪些查询以及它们花费了多少时间，我发现了一个关于 local.oplog.rs 的查询运行时间超过 4000 秒，以下是相关查询

         {
            "desc" : "WT RecordStoreThread: local.oplog.rs",
            "threadId" : "139625785952000",
            "active" : true,
            "opid" : "rs0:145981225",
            "secs_running" : 4168,
            "microsecs_running" : NumberLong("4168129663"),
            "op" : "none",
            "ns" : "local.oplog.rs",
            "query" : {

            },
            "numYields" : 0,
            "locks" : {

            },
            "waitingForLock" : false,
            "lockStats" : {
                "Global" : {
                    "acquireCount" : {
                        "r" : NumberLong(1),
                        "w" : NumberLong(1)
                    }
                },
                "Database" : {
                    "acquireCount" : {
                        "w" : NumberLong(1)
                    }
                },
                "oplog" : {
                    "acquireCount" : {
                        "w" : NumberLong(1)
                    }
                }
            }
        },

有人可以解释一下吗？这个查询在做什么，我应该担心吗？

Answer 1

这些是与复制相关的线程。它们是正常操作的一部分。

• WT RecordStoreThread:local.oplog.rs
• rsSync
• rsBackgroundSync
• ReplBatcher

实际上存在一个关于默认显示这些结果的公开错误，而这些结果可能应该隐藏，因为它们总是长时间运行的操作:https://jira.mongodb.org/browse/SERVER-28257

来自错误报告:

At present db.currentOp() by default shows replication-related threads such as:

"WT RecordStoreThread: local.oplog.rs"

"rsSync"

"rsBackgroundSync"

"ReplBatcher"

Often these operations are long running and users may get a wrong impression that there is a performance problem.